Molecules and Light 2011

Transkrypt

Molecules and Light 2011
Autumn Meeting of the Polish Photochemistry Group
Zakopane, 19-23 September 2011
Book of Abstracts
Institute of Physical Chemistry PAS, Warsaw
Jagiellonian University, Cracow
Adam Mickiewicz University, Poznań
www.ichf.edu.pl/ml2011
Official conference web site:
www.ichf.edu.pl/ml2011
Important Information
Conference venue: Hotel Pod Berłami, Zakopane, ul. Grunwaldzka 9
Tel./fax: +48 18 20 132 21, www.podberlami.com
(all lectures, communications, panel discussion
and poster session)
Welcome Dinner:
(19 Sept. 2011)
Hotel Carlton, Zakopane, ul. Grunwaldzka 11
Tel.: +48 18 20 144 15, www.carlton.pl
Conference Dinner: Karczma Kmicic, Zakopane, ul. Grunwaldzka 25B
(21 Sept. 2011)
Tel./fax: +48 18 20 663 33, www.karczmakmicic.pl
Edition: Jerzy Karpiuk
Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw
Jagiellonian University, Cracow
All rights reserved.
Molecules and Light 2011, Zakopane 19-23 September 2011
Page 2
Organizing Committee
Conference Chairmen
Jerzy Karpiuk (Institute of Physical Chemistry PAS, Warsaw)
Marek Mac (Faculty of Chemistry, Jagiellonian University, Cracow)
Members
Ewelina Karolak-Solarska (Institute of Physical Chemistry PAS, Warsaw)
Ewa Kuliś (Faculty of Chemistry, Jagiellonian University, Cracow)
Alina Majka (Institute of Physical Chemistry PAS, Warsaw)
Marek Sikorski (Faculty of Chemistry, Adam Mickiewicz University, Poznań)
Exhibitors
COMEF Aparatura Naukowo-Badawcza, Katowice
EUROTEK International, Warsaw
Merck Sp. z o. o., Warsaw
Page 3
Table of Contents
Table of Contents
Important Information......................................................... 2
Organizing Committee........................................................ 3
Exhibitors ............................................................................ 3
Welcome .............................................................................. 5
Conference Program .......................................................... 6
Plenary Lectures ............................................................... 11
Invited Lectures ................................................................ 19
Panel Discussion .............................................................. 27
Oral Communications....................................................... 33
Posters .............................................................................. 49
Page 4
Welcome
Welcome
Dear colleagues and friends,
It is our honour and pleasure to welcome you in Zakopane to attend the Molecules and Light 2011 Conference.
The Conference is organised as an autumn meeting of the Polish Photochemistry Group with the aim to serve as a forum to review current research conducted in Poland in the field of photochemistry and photophysics, and to provide opportunity for establishing and strengthening scientific and personal contacts between the members of our community. We organise the meeting under
the auspices of the European Photochemistry Association, as the Polish Section of the EPA, as we feel it is an excellent platform to combine a national
view of our field with an international perspective.
We are happy that many young researchers, postdocs, PhD and graduate
students, have positively responded to our initiative, which gives us the feeling
that such a meeting has been expected and needed in our community. We
would also like to thank all those who have kindly accepted the invitation to
deliver a lecture. The onset of the autumn, with its beautiful colours, but also
with the approaching beginning of the new academic year, is especially appropriate time not only to review and reconsider recent advances but also to
inspire with new concepts and ideas on molecules and light. That’s also, why
we hope to continue our initiative in future.
Our meeting is a joint effort of three institutions: the Institute of Physical
Chemistry of the Polish Academy of Sciences, the Jagiellonian University and
the Adam Mickiewicz University, and we sincerely acknowledge their financial
support. We thank also our exhibitors: Comef, Eurotek and Merck Sp. z o.o.
for their contributions.
We wish you scientifically challenging, productive and inspiring meeting. We
also hope you will enjoy numerous attractions of the capital of Polish Tatra
Mountains.
Jerzy Karpiuk, Marek Mac, Marek Sikorski
19 September 2011, Zakopane
Page 5
Conference Program
Conference Program
Monday, 19 September, 2011
Monday, 19 September, 2011:
14.00-19.00
Registration
Monday, 19 September 2011
Evening Session: 19.00-20.15
19.00-19.15
19.15-20.15
Models and reality
Opening Session
Welcome addresses
Opening lecture
Jacek Waluk, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw
From models to reality: a (very) personal view of photoscience
20.15-23.00
Welcome dinner
Tuesday, 20 September 2011
Ultrafast spectroscopy
Morning Session: 9.00-13.00
Chairman: Jakob Wirz
Peter Vöhringer, Institute for Physical and Theoretical Chemistry, University of Bonn
9.00-10.00
PL1
Ultrafast dynamics of solvated electrons in H-bonded fluids
10.00-10.45
IL1
Gotard Burdziński, Faculty of Physics, Adam Mickiewicz University, Poznań
Ultrafast time-resolved studies of Wolff rearrangement process
10.45-11.15
Coffee break
11.15-12.00
IL2
Thomas Schultz, Max Born Institute, Berlin
12.00-12.20
OC1
12.20-12.40
OC2
12.40-13.00
OC3
Ultrafast spectroscopy of biomolecules and clusters
Jacek Kubicki, Faculty of Physics, Adam Mickiewicz University, Poznań
Direct observation of sulfonyl azide excited state and its decay processes by
ultrafast time-resolved IR and UV-Vis spectroscopy
Michał Kijak, Institute of Physical Chemistry, Polish Academy of Science, Warsaw
2-(2-Pyridyl)pyrrole: coupling of photoinduced electron/proton transfer with
conformational changes
Marek Sikorski, Faculty of Chemistry, Adam Mickiewicz University, Poznań
The ground- and excited-state double proton transfer in alloxazine and some
of its derivatives: Theoretical and experimental approach
Page 6
Conference Program
Photocatalysis, organic-semiconductor systems
Afternoon Session: 14.30-17.45 Chairman: Peter Vöhringer
Horst Kisch, Institute of Inorganic Chemistry, University of Erlangen-Nürnberg
14.30-15.30
PL2
Semiconductor visible light photocatalysis – principles and applications
Rafał Sadowski, Faculty of Chemistry, Jagiellonian University, Kraków
15.30-15.50
OC4
Photoactive titanium dioxide coatings on organic polymers
15.50-16.20
Coffee break
16.20-17.05
IL3
Wojciech Macyk, Faculty of Chemistry, Jagiellonian University, Kraków
17.05-17.25
OC5
17.25-17.45
OC6
Coordination compounds as photosensitizers of titanium dioxide
Marek Oszajca, Faculty of Chemistry, Jagiellonian University, Kraków
Photophysical and electrochemical features of semiconductors modified with
polynitriles
Agnieszka Podborska, Faculty of Chemistry, Jagiellonian University, Kraków
New optoelectronic logic devices based on surface-modified TiO2
Evening Session: 20.00-21.30
Poster session
Wednesday, 21 September 2011
Wednesday, 21 September 2011 Photochemistry, synthesis, new materials
Chairman: Jacek Waluk
Jakob Wirz, Department of Chemistry, University of Basel
9.00-10.00
PL3
Photoremovable protecting groups: How fast are they really?
10.00-10.45
IL4
Daniel Gryko, Institute of Organic Chemistry, Polish Academy of Sciences, Warsaw
Novel π-expanded porphyrins – synthesis and photophysics
10.45-11.15
Coffee break
11.15-12.00
IL5
Sebastian Maćkowski, Institute of Physics, Nicolaus Copernicus University, Toruń
12.00-12.20
OC7
12.20-12.40
OC8
12.40-13.00
OC9
Photomodification of corrole molecules
Mariusz Tasior, Institute of Organic Chemistry, Polish Academy of Sciences, Warsaw
The synthesis and optical properties of novel coumarins
Miłosz Pawlicki, Department of Chemistry, University of Wrocław
Radiationless deactivation of subpyriporphyrins
Maciej Nowak, Institute of Physics, Polish Academy of Sciences, Warsaw
Photon-induced and spontaneous transformations of the structure of cytosine
molecule
Wednesday, 21 September 2011, 14.00 – 18.00: Excursion
Wednesday, 21 September 2011
Evening, 19.30 – 23.00
Conference Dinner
Page 7
Conference Program
Thursday, 22 September 2011
Electron, proton, energy transfer
Chairman: Andrzej Sobolewski
Eric Vauthey, Department of Physical Chemistry, University of Geneva
9.00-10.00
PL4
Excitation energy hopping and photoinduced charge transfer processes in
multichromophoric systems
Gonzalo Angulo, Institute of Physical Chemistry, Polish Academy of Sciences, War10.00-10.45
saw
IL6
Electron transfer and diffusion
10.45-11.15
Coffee break
11.15-12.15
PL5
Klaas Zachariasse, Max-Planck-Institute for Biophysical Chemistry, Göttingen
12.15-12.35
OC10
12.35-12.55
OC11
12.55-13.15
OC12
Intramolecular charge transfer in the excited state. Dynamics and structure
Ewelina Karolak-Solarska, Institute of Physical Chemistry, Polish Academy of
Sciences, Warsaw
Electron transfer and photodissociation in a spirocyclic bichromophoric molecule
Anna Szemik-Hojniak, Department of Chemistry, University of Wrocław
Excited state deactivation processes in 3-aminoflavone
Jędrzej Solarski, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw
Investigation of the bi-molecular energy transfer processes in liquid solutions
Afternoon Session: 15.00-18.30
Panel Discussion
Photoinduced charge transfer and conformational changes
Chairman: Jerzy Karpiuk
15.00-16.30
PD
Part 1: Address sent by Zbigniew R. Grabowski
16.30-17.00
Coffee break
17.00-18.30
PD
Part 2: Open discussion: short contributions are welcome
Contributions: Jacek Waluk and Klaas Zachariasse
Page 8
Conference Program
Friday, 23 September 2011
Friday, 23 September 2011
Theory and computations
Chairman: Eric Vauthey
Andrzej Sobolewski, Institute of Physics, Polish Academy of Sciences, Warsaw
9.00-10.00
PL6
Photophysics of hydrogen bonded systems: from theory to applications
Piotr Skurski, Department of Chemistry, University of Gdańsk
10.00-10.45
IL7
Unusual oxidizing agents
10.45-11.15
Coffee break
11.15-11.35
OC13
Przemysław Kolek, Institute of Physics, Rzeszów University
11.35-11.55
OC14
11.55-12.15
OC15
12.15-12.30
Supersonic jet spectra and ab initio modelling of S0→S1 transition of anthranilic acid molecule
Piotr Kasprzycki, Institute of Experimental Physics, University of Warsaw
Electron localization function, noncovalent interactions analysis and other
theoretical tools in photochemistry
Michał Rode, Institute of Physics, Polish Academy of Sciences, Warsaw
Substituent effect on the energetical landscape of the molecular photoswitch
Closing remarks
Page 9
List of Posters
Posters:
P1
P2
P3
P4
P5
P6
P7
P8
P9
P10
P11
P12
P13
P14
P15
P16
P17
P18
Iwona Anusiewicz, Sylwia Freza, Department of Chemistry, University of Gdańsk
Superalkalies forming stable molecules with electron acceptors
Marta Brzeska, Institute of Applied Radiation Chemistry, Technical University of Łódź
Photodegradation of reactive azo dyes by Advenced Oxidation Proces
Katarzyna Filipczak, Faculty of Chemistry, Adam Mickiewicz University, Poznań
Spectral and photophysical properties of individua formed by selected photochromic
Schiff bases in the ground and excited states
Sylwester Gawinkowski, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw
SERS studies of porphycene
Mateusz Gierszewski, Faculty of Chemistry, Adam Mickiewicz University, Poznań
Spectral and photophysical properties of (E)-N-(alkyl-carbonyl-alhoxy)-2’(4’)-hydroxy-4stilbazolium halides
Marta Gmurek, Faculty of Process and Environmental Engineering, Technical University of Łódź
2-Chlorophenol photooxidation using meso-tetraphenylporphyrin immobilized into polyurethane nanofabrics
Aleksander Gorski, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw
Polymorphism in 1H-Pyrrolo[3,2-h]quinoline: experimental and theoretical study
Natalia Gutowska, Faculty of Chemistry, Adam Mickiewicz University, Poznań
Spectroscopic properties of individua formed by imidazolium ionic liquids with chloride
and tetrafluoroborate anions
1 +
13 17
Analysis of the high excited B Σ Rydberg state in the rare C O isotopic molecule
1 + 1
-1
Spectroscopy of the B Σ -A Π Ångström system in the optical range 19200-21100 cm
13 16
for the C O isotopic molecule
Dominik Koszelewski, Institute of Organic Chemistry, Polish Academy of Sciences, Warsaw
π-Expanded porphyrins - synthesis and photophysics
Ewa Krystkowiak, Faculty of Chemistry, Adam Mickiewicz University, Poznań
Hydrogen bonds energy changes upon excitations of aminocoumarins determined from
absorption solvatochromic experiment
Aneta Lewkowicz, Institute of Experimental Physics, University of Gdańsk
Fluorescent properties of Rhodamine 6G in different xerogel nanolayers and bulk materials
Tomasz Uchacz, Faculty of Chemistry, Jagiellonian University, Kraków
New fluorescent sensors based on 1H-Pyrazolo[3,4-b]quinoline skeleton
Alina Majka, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw
Solvent controlled photophysics of siprocyclic lactones
Maria Pszona, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw
Analysis of absorption and emission spectra of Photofrin
Jacek Wierzchowski, Faculty of Food Sci., University of Warmia & Mazury in Olsztyn
8-Azapurines: fluorescent, isosteric alternatives to natural purine bases
Michał Rode, Institute of Physics, Polish Academy of Sciences, Warsaw
Substituent effect on the energetical landscape of the molecular photoswitch
- poster supplementing oral communication OC15
Page 10
Plenary Lectures
Plenary Lectures
Page 11
Opening Lecture
From models to reality: a (very) personal view of photoscience
Waluk J.
Institute of Physical Chemistry, Polish Academy of Sciences, [email protected]
A fundamental requirement for each branch of science is to establish general models for the
phenomena it deals with, and to apply these models to particular systems. In order to
understand elementary photoinduced processes, such as electron, proton, or hydrogen transfer,
several model molecules have been studied for such a long time and so intensely that they
earned a paradigm status. Using selected examples, I will discuss difficulties, controversies,
uncertainties, and pitfalls encountered while studying these “classical” or “standard” systems.
Page 12
Plenary Lectures
Ultrafast dynamics of solvated electrons in H-bonded fluids
Vöhringer P.
1
Institute for Physical and Theoretical Chemistry, University of Bonn
The solvated electron is an elusive transient species whose spectroscopic and dynamical
properties pose until today entirely unresolved and highly intriguing puzzles. Depending on the
medium, solvated electron can
either be generated chemically
(e.g. the ammoniated electron) or
they need to be formed via interaction of the solvent with ionizing
radiation
(e.g.
the
hydrated
electron).
In both cases, the detailed
nature of the structural motifs of
electron binding to the liquid environment
is
a
controversially
debated subject. Does the solvated
electron
occupy
hydrogen-like
eigenstates
in
a
„quasi”-spheriodal
Fig.1 Probability of the solvated electron surviving the geminate
recombination in liquid-to-supercritical water as a function of the void of the liquid (i.e. a „cavity”
electron) or is it better described as
temperature and density-dependent dielectric constant.
an extended solvent-stabilized
molecular anion cluster (i.e. a molecular species)? Furthermore, the nature of the primary
molecular events by which thermalized and fully solvated electrons can be created photolytically
are also open to scientific discussions. How can solvated electrons be created with photon
energies well below the vertical ionization threshold and at what distances, r0, from the inital
ionization site are the excess charges finally in equilibrium with its solvent surroundings? What
are the molecular mechanisms and what are their time scales that are involved in electron annihilation in the liquid medium?
Our research is targeted at providing experimental insights into these fundamental questions. We use femtosecond time resolved spectroscopy to explore the dynamics of solvation
and non-adiabatic relaxation of fully thermalized electrons in response to their ultrafast optical
excitation. [1,2] Furthermore, femtosecond multiphoton-ionization with near-infrared probing is
used to reveal the dynamics of recombination of the geminate charge carriers including the
solvated electron itself. These experiments are carried out on electrons dissolved in hydrogenbonded solvents over as wide a range of temperature and density thereby covering the liquid
and the supercritical phase of the solvent.[3] In combination with detailed numerical calculations
including direct-flight Monte-Carlo simulations, this approach also enables us to disentangle the
role of the various pathways ultimately leading to electron decay.[4]
[1] J. Lindner, A.-N. Unterreiner, and P. Vöhringer, Chem. Phys. Chem. 7, 363 (2006)
[2] J. Lindner, A.-N. Unterreiner, and P. Vöhringer, J. Chem. Phys. 129, 064514 (2008)
[3] S. Kratz, J. Torres-Alacan, J. Urbanek, J. Lindner, and P. Vöhringer, Phys. Chem. Chem. Phys. 12,
12169 (2010)
[4] J. Torres-Alacan, S. Kratz, and P. Vöhringer, submitted 2011
Page 13
Plenary Lectures
Semiconductor Visible Light Photocatalysis –
Principles and Applications
Kisch, Horst
Institute of Inorganic Chemistry, University of Erlangen-Nürnberg
[email protected]
The chemical conversion and utilization of solar energy is based on light-induced charge
generation and subsequent redox reactions with donor/acceptor molecules. Since relevant
substrates usually do not absorb sunlight, a photocatalyst is necessary to enable chemical
transformations. Natural photosynthesis is the most important example for such a type of process. Water is oxidized to oxygen and carbon dioxide to carbohydrates.
Whereas many homogeneous molecular photocatalysts (photosensitizers) may undergo
photo-induced charge generation, fast recombination usually prevents efficient redox reactions.
This is different is the case of (heterogeneous) semiconductor photocatalysts, wherein the surface-trapped are able to simultaneously reduce and oxidize acceptor and donor molecules at
the solitd-liquid or solid-gas interphase. In this lecture the following aspects will be discussed
[See e.g. ref.1-3].
i)
ii)
Basic Principles of Semiconductor Photocatalysis
Preparation and Characterization of Semiconductor Powders - Surface Modification of
Titania
iii) Controlling the Efficiency of Charge Generation
iv) The Problem of Comparing Apparent Quantum Yields
v)
Classification of Semiconductor Photocatalyzed Reactions
vi) Aerobic Photooxidation Reactions for Pollutant Removal
vii) Anaerobic C-N and C-C Coupling Reactions for New Organic Syntheses
viii) Water Cleavage, Nitrogen Fixation, and Activation of Alkanes.
[1] H. Kisch, Adv. Photochem. 62(2001) 93-143.
[2] H. Kisch, W. Macyk, ChemPhysChem 3(2002)399-400.
[3] D. Mitoraj, H. Kisch, Angew. Chem. Int. Ed. 47(2008)1-5.
Page 14
Plenary Lectures
Photoremovable protecting groups: How fast are they really?
Jakob Wirz
1
Department of Chemistry, University of Basel, Switzerland, [email protected]
Photoremovable protecting groups (PPG’s) provide spatial and temporal control over the release of various chemicals such as bioagents (neurotransmitters, cell signaling molecules),
acids, bases, Ca2+ ions, oxidants, etc. [1–3] The talk will cover recent developments in the field,
focusing on reaction mechanisms.
[1] Pelliccioli, A. P.; Wirz, J., Photochem. Photobiol. Sci. 2002, 1, 441.
[2] Klán, P.; Bochet, C.; Givens, R. S.; Popik, V.; Wirz, J. Chem Rev., in preparation (2012).
[3] Photochem. Photobiol. Sci., Special issue on Photoremovable protecting groups, Feb. 2012.
Page 15
Plenary Lectures
Excitation energy hopping and photoinduced charge transfer processes in multichromophoric systems
Eric Vauthey
Department of physical chemistry, University of Geneva, eric.vauthey@unige,ch
Molecular systems containing several identical chromophoric units have found many types of
applications, from artificial photosynthesis to DNA detection and molecular electronics. We will
present some of our results obtained by ultrafast optical spectroscopy with various multichromophoric systems going from molecules with two chromophoric units to more complex
systems with up to ten units.
We will concentrate on two main processes that can take place in these arrays: excitation energy hopping and charge transfer. The first one is common to most systems and takes place within a few picoseconds. We will show that the dynamics of energy hopping in a bichromophoric
[1]
system intercalated into DNA can yield interesting conformational information.
Photoinduced charge separation (CS) between identical chromophoric units is less common
and we will discuss some of our efforts to undertand the direction of the charges in such sym[2]
metry-breaking process.
Finally, the excited-state dynamics of multichromophoric systems consisting of eight to ten
core-substituted naphtahlenediimide (NDI) chromophores covalently attached to a p- octiphenyl
(POP) or an oligophenylethynyl (OPE) scaffold will be discussed. It will be shown that in a lipid
bilayer, POP-NDI systems self-organise in a tetrameric architecture allowing photoinduced
[3]
transmembrane electron transport. Both POP-NDI and OPE-NDI systems also self-assemble
[4]
on gold surfaces resulting to photocurrent generation. All the CS pathways as well as the
[5,6]
ensuing charge recombination (CR) channels have been elucidated.
Our investigations reveal that, depending on the nature of the NDI core- substituents and on the scaffold, as well as on
the excitation wavelength, either symmetry breaking CS between two NDI moieties or CS between the scaffold and a NDI unit take place. These processes result to charge-separated states with different lifetimes and thus different efficiencies for photocurrent generation. Although
very long-lived charge separation (> ms) was not realised in these systems, this study opens
several promising new avenues for ultrafast CS and slow CR.
[1] A. Fürstenberg, M.D. Julliard, T.G. Deligeorgiev, N.I. Gadjev, A.A. Vassilev, E. Vauthey, J. Am.
Chem. Soc. 128, 7661 (2006)
[2] V. Markovic, D. Villamaina, I. Barabanov, L. M. Lawson Daku, E. Vauthey, Angew. Chem. Int. Ed,
50, (2011), doi:10.1002/anie.201102601.
[3] S.A.L. Bhosale, P. Talukdar, A. Fürstenberg, N. Banerji, E. Vauthey, G. Bollot, J. Mareda, C. Röger,
F. Würthner, N. Sakai, S. Matile, Science, 313, 84 (2006).
[4] A.L. Sisson, N. Sakai, N. Banerji, A. Fürstenberg, E. Vauthey, S. Matile, Angew. Chem. Int. Ed. 47,
3727 (2008).
[5] N. Banerji, A. Fürstenberg, S. Bhosale, A.L. Sisson, N. Sakai, S. Matile, E. Vauthey, J. Phys. Chem.
B. 112, 8912 (2008).
[6] N. Banerji, G. Duvanel, A. Perez-Velasco, S. Maity, N.Sakai, S. Matile, E. Vauthey, J. Phys. Chem. A
113, 8202 (2009).
Page 16
Plenary Lectures
Intramolecular Charge Transfer in the Excited State.
Dynamics and Structure
Zachariasse K. A.
Max-Planck-Institute for Biophysical Chemistry
Spectroscopy and Photochemical Kinetics, Göttingen, Germany, [email protected]
With 4-(dimethylamino)benzonitrile (DMABN) intramolecular charge transfer (ICT) takes place in
1
o
2
the excited state, with a reaction time of 4 ps in acetonitrile (MeCN) at 25 C. Changing the
structure of the amino substituent has a large effect on the ICT reaction, as will be shown for
4-(di-tert-butylamino)benzonitrile (DTABN), 3-(di-tert-butylamino)benzonitrile (mDTABN), 4(diisopropylamino)benzonitrile (DIABN), and 6-cyanobenzoquinuclidine (CBQ). In addition, new
3
results on ICT with 6-N,N-dialkylaminopurines and the six isomers of dicyano-N,N-dialkylaniline
are presented. As experimental methods, picosecond time correlated single photon counting
(SPC) and femtosecond excited state absorption (ESA) are employed.
ICT is also observed in several rigidized molecules: 1-tert-butyl-6-cyano-1,2,3,4tetrahydroquinoline (NTC6), fluorazene (FPP), and 4-cyanofluorazene (FPP4C). These results
show that in such systems, fast ICT to a planar ICT state can take place, on a potential energy
surface with a barrier between the initially excited (LE) and ICT states. This means that large
amplitude motions such as a perpendicular twist of the amino group are not required for ICT.
The electronic coupling between the electron donor and acceptor parts of the molecules appears to be substantial in the ICT state.
[1] Z.R. Grabowski, K. Rotkiewcz, W. Rettig, Chem. Revs. 103, 3899 (2003).
[2] S.I. Druzhinin, N.P. Ernsting, S.A. Kovalenko, L.P. Lustres, T.A. Senyushkina, K.A. Zachariasse,
J. Phys. Chem. A 110, 2955 (2006).
[3] A. Demeter, S.I. Druzhinin, S.A. Kovalenko, T.A. Senyushkina, K.A. Zachariasse, J. Phys. Chem. A
115, 1521 (2011).
Page 17
Plenary Lectures
Photophysics of hydrogen bonded systems:
from theory to applications
Sobolewski A. L.
Institute of Physics, Polish Academy of Sciences, 02-668 Warsaw, Poland, [email protected]
Hydrogen bonds are ubiquitous in organic matter. They govern, for example, molecular recognition in DNA and determine to a large extent the secondary structure of proteins. While the
structure and functionality of hydrogen bonds in the electronic ground state have been investigated since decades and are thus quite well understood, much less is known on the properties
of hydrogen bonds in excited electronic states and on their role in photochemical processes.
We have shown recently that radiationless deactivation channel associated with conical intersection (CI) between the electronically excited state and the ground state for proton-transfer
reaction along intra- or inter-molecular hydrogen bonds may provide a very effective mechanism
for explanation of functionality of commercial organic photostabilizers [1], and the photostability
of biological molecules such as DNA [2] and proteins [3], respectively.
In this presentation some potential applications of the above mentioned phenomena will be
outlined. Thus the mechanistic aspects of the excited-state intra-molecular proton-transfer
(ESIPT) process may be utilized in construction of optically driven photostable molecular
switches - (a) [4], while the electron-driven proton-transfer (EDPT) phenomenon along the intermolecular hydrogen bond(s) may provide a template for designing of macromolecular systems,
like Mg-porphyrin (MgP) and benzoquinone (BQ) shown below - (b), which are able to oxidize
water using solar (VIS) radiation [5].
(a)
S1
(b)
S1’
CI
λ1
λ2
S0
PA
Y
H
HY
Y
X
Z
Y
Y
H
H
X
Z
X
Z
X
hv
S0’
X
Z
Z
H
MgP + 2H2O + 2BQ +2hv ---> MgP + O2H2 + 2BQH
PDA
PT
Twist
PT
[1] A.L. Sobolewski, W. Domcke, C. Hättig, J. Phys. Chem. A 110, 6301 (2006)
[2] A.L. Sobolewski, W. Domcke, C. Hättig, Proc. Nat. Acad. Sci. 102, 17903 (2005)
[3] D. Shemesh, A.L. Sobolewski, W. Domcke, J. Am. Chem. Soc., 131, 1374 (2009)
[4] A.L. Sobolewski, Phys. Chem. Chem. Phys, 10 (2008) 1243
[5] A.L. Sobolewski, W. Domcke, J. Phys. Chem. A 112, 7311 (2008)
Page 18
Invited Lectures
Invited Lectures
Page 19
Invited Lectures
Ultrafast time-resolved studies of Wolff rearrangement process
Burdziński G.
Faculty of Physics, Adam Mickiewicz University, Poznań, [email protected]
Photochemical Wolff rearrangement process of diazo carbonyl compounds in solution has
been extensively studied by ultrafast transient absorption spectroscopy with UV–Vis and mid-IR
detection with the aid of modern computational
concerted
1N2*
methods [1]. Two paths of Wolff rearrangement
-N2
R2
R
R
1
2
reaction should be considered: stepwise (carbene
R1
R1
O
mediated) and concerted. The latter means that
O
C O
product is formed in the diazo singlet excited state
R2
ISC
IC
hv
in concert with molecular nitrogen extrusion.
solvent
Accordingly to Kaplan and Meloy’s rule [4],
N2
R2
proposed over 40 years ago, concerted Wolff
R1
products
R2
R1
O
rearrangement process is favored in the syn
O
conformers of α-diazo carbonyl compounds, while
Scheme
1. Different reaction pathways
the light activation of anti conformers promotes
for diazo ketones.
the
stepwise
process.
R1
R2
Our ultrafast UV-vis and IR results [1-3] for acyclic diazo carbonyl
C O
R1
R2
compounds (diazoacetone, azibenzil, p-biphenyl methyldiazo
O
ketone) agree with Kaplan and Meloy’s rule. Since typical lifetime of
hv -N2
hv -N2
diazo singlet excited state is less than 0.3 ps, concerted process
can be confirmed by a fast product rise (< 0.3 ps). The stepwise
N2
N2
process with carbene intermediacy results in a slower product rise
R2
O
R1
R1
(> 1 ps) depending on carbene lifetime. The excess of vibrational
R2
O
energy in the nascent carbene species can be also an important
anti
syn
factor increasing the rate of carbene-ketene isomerization process.
Scheme 2. Concerted and
The short (< 0.3 ps) lifetime of the diazo excited state may also
stepwise processes.
indicate that the syn and anti forms produced with UV light pulse do
not interconvert, thus the photochemistry proceeds from the
Franck-Condon state. Recently hetero Wolff rearrangement process has been studied by timeresolved spectroscopy, formation of thioketene and thiirene intermediates has been observed
for 1,2,3-thiadiazoles.
[1] G. Burdzinski, M. Platz, J. Phys. Org. Chem. 23, 308 (2010)
[2] G. Burdzinski, Y. Zhang, J. Wang, M. Platz, J. Phys. Chem. A 114, 13065 (2010)
[3] G. Burdzinski, J. Wang, T. Gustafson, M. Platz, J. Am. Chem. Soc. 130, 3746 (2008)
[4] F. Kaplan, G. Meloy, J. Am. Chem. Soc. 88, 950 (1966)
Page 20
Invited Lectures
Ultrafast Spectroscopy of Biomolecules and Clusters
1
Thomas Schultz
1
Max Born Institute Berlin, [email protected]
electrons
ions
Chemical reactions involve the breaking and forming of chemical bonds between atoms. The
speed of such transformations is limited by the timescale of nuclear motion along the reaction
coordinate. With femtosecond time-resolved spectroscopy, chemical reactions can be observed
in real time and the pathway from educt to product can be characterized. We combine gasphase spectroscopy and high-level theory to resolve the mechanism of excited state processes
in
isolated
biomolecules. In their
τ ≈ 0.1, 1.3, 1000 ps
native environment,
however,
the
biomolecules interact
with a local envi0
2
4
100 200
pump-probe delay (ps)
ronment
(typi-cally
water or other biox20
*
molecules). Whether
IPad =
T
gas-phase
results
8.0 eV
offer
relevant
A2(H2O)n
A(H2O)n
contributions to-wards
100
200
300
400
0
1
2
3
4
the understanding of
ion mass (u)
electron kinetic energy (eV)
real
biological
Fig.1 (adapted from [1]) Femtosecond time-resolved mass and electron
systems is therefore
spectroscopy of biomolecular clusters. A species of interest (e.g. the
heavily dis-puted. We
microhydrated base pair adenine2-(H2O)3) is identified in the mass specbridge
the
gap
trum (left) and relevant excited state processes are analysed via correbetween the isolated
lated time-resolved mass (top right) and electron spectra (bottom right).
and
the
solvated
species
with
experiments on isolated molecules, microhydrated clusters, and species in a liquid water jet.
With pump-probe ionization experiments for all spe-cies, we strive to identify the photochemical
pro-cesses within and without the local environment.
The information content of spectroscopy is always limited by the spectroscopic resolution
and, according to the Heisenberg uncertainty principle, the energy resolution cannot exceed
∆E⋅∆t ≥ h. In femtosecond pump-probe experiments, this limit is quite severe because the observation time ∆t is limited by the femtosecond duration of the laser pulses. Hence, the information content of femtosecond experiments does not scale favorably for the investigation of larger
molecules with many degrees of freedom, and is insufficient to characterize the structure of
larger biomolecules or clusters. A novel technique of correlated rotational alignment spectroscopy (CRASY, [2]) combined high-resolution rotational spectra with femtosecond pump-probe
data and will help the investigation of systems with more complex structure in the future.
[1] V.R. Smith, E. Samoylova, H.-H. Ritze, W. Radloff, T. Schultz, PCCP 12, 9632 (2010).
[2] Christian Schröter, Kyriaki Kosma, Thomas Schultz, SCIENCE 333, 1011 (2011).
Page 21
Invited Lectures
Coordination compounds as photosensitizers of titanium dioxide
Wojciech Macyk
Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków, Poland
e-mail: [email protected]
Photochemistry of coordination compounds in solutions is very often related to homogeneous photocatalytic processes. Small molecules activation, photoinduced redox reactions or
ligand substitution are common examples of light-driven processes involving metal complexes.
Change of the oxidation state of metal ion elicited by charge transfer excitation is usually a keystep initiating a photocatalytic process. Photoinduced charge transfer processes, involving central atom of a complex, take place in heterogeneous photocatalysis, also that based on titanium
dioxide. Already TiO2 excitation can be considered as a ligand to metal charge transfer, in which
–II
IV
electron is transferred from the ligand (O ) to titanium center (Ti ). As a result the oxidized
–I
III
ligand (O , i.e. hole in the valence band) and reduced titanium (Ti , i.e. electron in conduction
band) are formed. Similarly, photosensitization of TiO2 by metal complexes (of ruthenium, platinum, iron, titanium and others) characterized by CT bands and suitable redox properties, plays
a key-role in modern heterogeneous photocatalysis.
Photosensitization may proceed according to various mechanisms involving physical
(e.g. light absorption, intersystem crossing, etc.) and chemical (e.g. redox reactions, ligand
substitution, rearrangements, etc.) processes. Usually, a photoinduced electron injection from
the excited state of the photosensitizer to conduction band of TiO2 plays a crucial in these
mechanisms. Titanium dioxide is then reduced while the photosensitizer is oxidized. However,
the photosensitizer in its excited state is a stronger reductant and oxidant at the same time. Is
then a process of photosensitization, involving TiO2 oxidation by excited photosensitizer, possible at all? Can we use photochemistry of coordination compounds in solution to describe processes governing the heterogeneous photocatalysis? These aspects related to photosensitization of TiO2, as well as photochemistry and photophysics of coordination compounds, will be
discussed during the presentation.
References
[1]
[2]
[3]
[4]
[5]
[6]
H. Kisch, W. Macyk, Visible-light photocatalysis by modified titania, ChemPhysChem 3, 399-400
(2002)
K. Szaciłowski, W. Macyk, A. Drzewiecka-Matuszek, M. Brindell, G. Stochel, Bioinorganic photochemistry. Frontiers and mechanisms, Chem. Rev. 105, 2647-2694 (2005)
G. Stochel, M. Brindell, W. Macyk, Z. Stasicka, K. Szaciłowski, Bioinorganic Photochemistry (Wiley,
Chichester, 2009)
K. Szaciłowski, W. Macyk, M. Hebda, G. Stochel, Redox-controlled photosensitization of nanocrystalline titanium dioxide, ChemPhysChem 7, 2384-2391 (2006)
W. Macyk, K. Szaciłowski, G. Stochel, M. Buchalska, J. Kuncewicz, P. Łabuz, Titanium(IV) complexes
as direct TiO2 photosensitizers, Coord. Chem. Rev. 254, 2687-2701 (2010)
J. Kuncewicz, P. Ząbek, G. Stochel, Z. Stasicka, W. Macyk, Visible light driven photocatalysis in
chromate(VI)/TiO2 systems – improving stability of the photocatalyst, Catal. Today 161, 78-83 (2011)
Page 22
Invited Lectures
Novel π-expanded porphyrins – synthesis and photophysics
,1,2
Daniel T. Gryko,*
1
1
1
Agnieszka Nowak-Król, Dominik Koszelewski, Aleksander Re3
3
3
bane, Mikhail Drobizhev, and Erich Beuerman
Institute of Organic Chemistry of the Polish Academy of Sciences, Warsaw, Poland
2
Warsaw University of Technology, Faculty of Chemistry, Warsaw, Poland
3
Department of Physics, Montana State University, Bozeman, MT 59717, USA
Optical limiting is a nonlinear effect consisting of a decrease in the transmittance of the NLO
material under high-intensity illumination. Among different functions optical limiting devices can
perform, the most useful one is the protection of optical elements, sensors and human eye
against damage by exposure to a sudden high-intensity light. Dipolar or quadrupolar aromatic
molecules have been shown to be of particular interest since they allow combining very fast
(femtoseconds) intrinsic two-photon absorption (2PA) with somewhat slower reversed saturable
absorption (RSA).
We have developed the general principle to design porphyrins possessing low melting-point
and
we
synthesized
first
liquid
porphyrins:
5,10,15,20-tetrakis[3,4,5tris(decyloxy)phenyl]porphyrin and 5,10,15,20-tetrakis[3,4,5-tris(undecyloxy)phenyl]porphyrin.
We also developed conceptually new strategy towards π-expansion of porphyrin ring, which
relies on anion-radical coupling of suitable meso-substituted metallated porphyrins. Very recently we discovered the superior reagent for carrying out intramolecular oxidative coupling of porphyrins which avoids formation of troublesome side-products. All these developments combined
with liquid porphyrin principle allowed us to produce first liquid porphyrin possessing large twophoton absorption cross-section – suitable for optical limiting.
Page 23
Invited Lectures
Photomodification of corrole molecules
Mackowski S.
Institute of Physics, Nicolaus Copernicus University, Toruń, [email protected]
Corroles are synthetic, aromatic macrocycles of tetrapyrrolic family that also includes porphyrins and phthalocyanine. Interest in these compounds has grown recently as these molecules could be potentially used for antitumor therapy, catalytic and optical sensor devices, and
artificial light-harvesting systems.
In this work we describe the optical properties of 5,10,15-tris(pentafluorophenyl)corrole, one
of the most studied member of this family. Two particular aspects will be discused in detail.
Firstly, we demonstrate that upon illumination with a UV light, the corrole undergoes strong
photomodification: new emission bands appear which are characterized with different fluorescence decay times. This effect depends strongly upon the excitation power and is absent when
the corrole is excited with 532 green laser. Possible sources of this highly surprising effect will
be speculated about.
Secondly, we coupled corrole molecules with plasmon excitations in single silver nanowires
in an attempt to describe the effect of plasmons upon the optical properties of the corrole. Using our home-built confocal fluorescence imaging microscope we can determine the position of
the nanowire and correlate it precisely with the fluorescence image. The result of this work
show that we can strongly enhance the fluorescence intensity of corrole emission via plasmon
excitation.
Research at NCU has been supported by the WELCOME project “Hybrid Nanostructures as
a Stepping Stone towards Efficient Artificial Photosynthesis” funded by the Foundation for Polish Science and EUROCORES project “BOLDCATS” funded by the European Science Foundation.
This work has been carried out in collaboration with the groups of Daniel Gryko (Warsaw)
Nicholas A. Kotov (Ann Arbor), and Wolfgang Heiss (Linz).
Page 24
Invited Lectures
Electron transfer and diffusion
1
Angulo G.
1
Many researchers will tell you that everything about electron transfer has already
been said. Many will tell you that diffusion in solution is perfectly understood. Despite
their opinion I will show in this seminar that none of the former statements is true. More1
over, I will show that a kuhnian revolution is on-going since the appearance of Encoun2
3
ter Theories (ET) and that this research programme is progressive, in terms of Lakatos .
This theoretical corpus is intended to deal with any kind of reaction and its modulation by
the diffusion of the reaction partners.
4
We will discuss the basics of electron transfer from the Marcus point of view . Then
an introduction to diffusion in solution will be presented along with the ET that match reactivity between freely moving independent reactants and their mobility. Afterwards,
several experiments will show our attempts to unsuccessfully falsify the theory, in the
5
6
popperian sense . These comprise studies of fluorescence quenching and ions recom7
bination as well as the dependence of both on the viscosity of the medium, the driving
force of the reaction and on the concentration of the quencher. Additionally, experiments
at very high quencher concentrations will be explained by articulating the theory to con8
sider the rotational effects on the reaction –which to our knowledge is the first example
9
of such behaviour since Rice stated the difficulties to observe them . The progressive
character of the ET will be finally demonstrated by showing new experiments on the de10
pendence of the quenching rate coefficient on the excitation light intensity .
Nevertheless, do not forget that “not only are facts and theories in constant disharmony,
11
they are never as neatly separated as everyone makes them out to be” .
[1] T. S. Kuhn The Structure of Scientific Revolutions (1962).
[2] A.I. Burshtein Adv. Chem. Phys. 2000, 114, 419. Ibidem 2004, 129, 105.
[3] I. Lakatos The Methodology of Scientific Research Programmes: Philosophical Papers Volume 1
(1978).
[4] R.A. Marcus J. Chem. Phys. 1956, 24, 966; J. Chem. Phys. 1956, 24, 979; J. Chem. Phys. 1957, 26,
867; Discuss. Faraday Soc. 1960, 29, 21; Ann. Rev. Phys. Chem. 1963, 15, 155.
[5] K. Popper Conjectures and Refutations: The Growth of Scientific Knowledge (1963).
[6] A. Rosspeintner, D. R. Kattnig, G. Angulo, S. Landgraf, G. Grampp, A. Cuetos Chem. Eur. J. 2007,
13, 6474. A. Rosspeintner, D. R. Kattnig, G. Angulo, S. Landgraf, G. Grampp Chem. Eur. J. 2008, 14,
6213. G. Angulo, D.R. Kattnig, A. Rosspeintner, G. Grampp, E. Vauthey Chem. Eur. J. 2010, 16, 2291.
[7] G. Angulo, G. Grampp, A.A. Neufeld, A.I. Burshtein J. Phys. Chem. A 2003, 107, 6913. V.S. Gladkikh, A.I. Burshtein, G. Angulo, G. Grampp PCCP 2003, 5, 2581.
[8] To be published.
[9] S.A. Rice Diffusion-Limited Reactions, in Comprehensive Chemical Kinetics 25, Bramford, C.H., Tipper, C.F.H.; Compton, R.G. Eds.; Elsevier, Amsterdam, 1985.
[10] P.K. Feyerabend Against Method: Outline of an Anarchistic Theory of Knowledge (1975).
Page 25
Invited Lectures
Unusual Oxidizing Agents
1
Skurski P.
1
Department of Chemistry, University of Gdańsk, [email protected]
The possibility of utilizing superhalogen molecules as strong oxidizing agents (electron acceptors) capable of forming stable compounds with moderately reactive or chemically inert
systems is demonstrated and discussed on the basis of theoretical considerations supported by
ab initio calculations.
The provided discussion covers the explanation of the hypothetical HAlCl4 acid instability
(the existence of the corresponding LiAlCl4, NaAlCl4, and KAlCl4 salts was confirmed whereas
their parent acid (HAlCl4) was identified as the HCl···AlCl3 adduct with the hydrogen chloride
moiety tethered weakly to the quasi-planar aluminum chloride molecule). As concluded, the
electron binding energy (VDE) of the neutral superhalogen AlCl4 molecule was the most important factor determining the ability to form a stable MAlCl4 compound (M=Li, Na, K). This finding
was further confirmed by demonstrating that the competition between the ionization potential
(IP) and VDE values is indeed a key factor for predicting the stability of certain novel species
(such as MgBX5, X=F, Cl). Namely, the reason why the MgBX5 molecules (which might be considered as composed of the MgX and BX4 fragments) are kinetically and thermodynamically
stable is the proper balance between the IP of the MgX moiety and the BX4 ability to accept an
excess electron (manifested by the VDE of its anionic daughter). Finally, it is demonstrated that
almost any neutral molecule (including those regarded as nearly non-reactive) might be assembled into a stable, strongly bound compound when combined with a properly designed superhalogen system. Moreover, it is shown that such a resulting compound exhibits partially ionic
character as its stability is a consequence of the substantial electron density flow to the oxidizing agent used.
In general, the results show the ability of the superhalogen systems to ionize even the molecules that are not commonly considered to act as the reducers. In other words, due to their
unusual properties, the superhalogens may act as enormously strong oxidizing agents capable
of forming stable ionic compounds when combined even with moderately reactive chemical
systems.
Page 26
Panel Discussion
Panel Discussion
Photoinduced Charge Transfer
and Conformational Changes
Page 27
Panel Discussion
Panel Discussion:
Photoinduced Charge Transfer and Conformational Changes
Grabowski Z. R.
Dear photochemical friends,
I am sorry to be unable – for health reasons – to attend the meeting. It is already nearly 40
years as I entered the EPA, being the first member from this side of the iron curtain. EPA has
been affiliated with the European Union, and therefore suspected by the one-time authorities to
be a Trojan horse of the West. It was really difficult to legalize the Polish Section of EPA. It
appeared much more difficult afterwards to establish EPA in other countries of the Eastern
Block.
EPA turned to be like a large and friendly family – in a broad cooperation in research, in
education, and even in form of a mutual help in the need. In Poland we experienced – in a
memorable way – the help from our photochemical friends when the martial law was imposed in
1981.
*
*
*
The development of photochemistry went generally from simple objects – atoms, diatomic
molecules – to the most complex biological structures or processes, and so called nanoparticle
multiphase systems from one side, to the single molecules on the other. Most advanced methods of theory and experiment are used, with enormous success. Nevertheless, even the photochemistry of rather simple molecules presents still a challenge for research and for imagination.
One is usually expecting the simplest and fastest photochemical
CH3
reactions in solutions should be the electron and proton transfer. Pro- H3C
N
tolytic (acid-base) reactions belonged to the earliest not only detected,
but also well understood from the mechanistic and kinetic points of
view. We owe it to Theodor Förster and Albert Weller. Much later, the
excited state intra-molecular proton transfer reactions (ESIPT, phototautomerisations) revealed that the excited state molecular structure
suitably modifies in the proton transfer reaction, and the molecular
DMABN
vibrations which promote the reaction are identified.
C
Half a century ago Ernst Lippert and his students discovered a
molecule (DMABN) which emits double fluorescence in absence of any
N
reaction partner. The ratio of intensity of the two bands, strongly dependent on the polarity of the solvent, indicated to an excited state reaction accompanied with a
huge increase of the dipole moment. It was an intramolecular electron transfer (ICT) reaction.
Hypotheses concerning the nature of the chemical change responsible for this dual fluorescence phenomenon and its applications multiplied with time, and the number of related papers
is already counted in thousands. Just to name a few: an inversion of states [Lippert]; excimer
formation [McGlynn; Mataga]; hydrogen bonding [Kosower; Cazeau-Dubroca]; exciplex with
o
the solvent [Chandross; Varma]; our hypothesis on the ~90 twist of the donor vs acceptor units
(zwitterionic biradical, twisted ICT state – TICT).
In our group, we synthesized a number of D-A analogs of DMABN, specially those with a
structure compelling the D and A units to be mutually twisted or rigidly coplanar already in the
ground state. This model gained much support, both from numerous theoretical calculations
and from new experimental methods.
Page 28
Panel Discussion
Paralel, however, there appeared an opposite view [Zachariasse] claiming the structural
change in the ICT state is toward a planar structure. This gained also much evidence, specially
in cases of various larger derivatives or analogs of DMABN. Also in our group it has been
shown [Herbich & Kapturkiewicz] that the compounds with a dialkylamino group as a donor, and
a larger aromatic system as acceptor, in the ICT state tend to be planar.
Hypothetical models multiplied, including structural changes of the donor or in the acceptor
unit. Moreover, it is shown that the structure of the benzene ring undergoes a quinoid or antiquinoid deformation in the excited states involved [Haas & Zilberg].
With respect to DMABN and its monocyclic analogs more and more refined methods were
applied, specially the picosecond and femtosecond time-resolved IR and resonance Raman
spectroscopy [i.a., Ma, Kwok & al.], in general supporting the TICT model. As a decisive proof
we considered the ingenious NMR experiment [Dobkowski, Waluk, Michl, & al.] which has
o
shown that the molecule in the ICT state passes through the 90 twist.
Nevertheless, new and unexpected findings revived the discussion on the ICT state of
DMABN: theoretical and experimental findings on the existence of a previously not considered
πσ* state and its role in the electron transfer [Sobolewski and Domcke; Lim & al.]. Even the
kinetics became an unsolved mystery – the decay of the ICT fluorescence and of its transient
absorption are claimed to be different…
My conclusion is that the insight into the nature and mechanism of the photochemical processes of even simple molecules offers still very many riddles and much inspiration to our imagination and research.
Let this meeting will help and inspire you !
Zbigniew R. Grabowski
Page 29
Panel Discussion
Panel Discussion:
Zachariasse K. A.
Max-Planck-Institute for biophysical Chemistry
Spectroscopy and Photochemical Kinetics,Göttingen, Germany, [email protected]
The occurrence of photoinduced intramolecular charge transfer (ICT) with electron donor(D)/acceptor(A) substituted benzenes, such as 4-(dimethylamino)benzonitrile (DMABN), is
mainly determined by the magnitude of the energy gap ∆E(S1,S2) between the two lowest excited singlet states. In the final ICT state, the D and A moieties are not electronically decoupled,
as, i.a., seen from the observation that this ICT state is fundamentally different from intermolecular exciplexes, with weakly coupled D and A subunits. This follows from the finding that the
energy E(ICT) can not be calculated from the redox potentials of D and A, in contrast to the
exciplexes. Examples are, the absence of an ICT reaction with 4-(methylamino)benzonitrile
1
(MABN) and the photophysical behaviour of the six dicyano-N,N-dimethylanilines (mnDCMAs).
With these mnDCMAs, an ICT reaction only takes place for the isomers with the smallest
∆E(S1,S2), notwithstanding the strongly enhanced electron affinity of dicyanobenzene (mnDCMAs) as compared with benzonitrile (DMABN). A perpendicularly twisted amino group is only
found with the ICT states of DTABN, mDTABN, and CBQ, rigidized molecules that are chemically forced into this unnatural twist. For an understanding of the excited state absorption spectra of aminobenzonitriles is should be realized that the absorption spectra of the radical anions
of substituted benzonitriles hardly depend on the nature of the substituents.
Looking back at the discussions on this topic, for a long time it was taken for granted that the
ICT state of the D,A-substituted benzenes has a perpendicularly twisted amino group, without
feeling the necessity to support this belief by experimental evidence. It then became apparent
2
that it is very difficult to disprove such a belief. Max Planck already remarked in 1946 that it
rarely happens that scientists change their opinions.
[1] V.A. Galievsky, S.I. Druzhinin, A. Demeter, S.A. Kovalenko, T.A. Senyushkina, P. Mayer,
K.A. Zachariasse, J. Phys. Chem. A 115, 000 (2011)
[2] M. Planck, Naturwissenschaften 33, 230 (1946): „Persönliche Erinnerungen aus alten Zeiten“
Page 30
Panel Discussion
Panel Discussion:
Excited state twisting: a rule or an exception?
Waluk J.
The fate of excited 4-(dimethylamino)benzonitrile remains a subject of never-ending discussions [1]. The bone of contention is the geometry of the molecule and its electronic structure.
It now seems that loss of planarity upon electronic excitation is quite common and important
as a trigger for efficient radtiationless depopulation. Based on our recent work [2], I will present
several examples of molecules in which excited state proton transfer seems to be accompanied
by twisting.
[1] T. Fujiwara, M. Z. Zgierski, E. C. Lim, Phys. Chem. Chem. Phys. 13, 6779 (2011),
and references therein.
[2] E. Nosenko, G. Wiosna-Sałyga, M. Kunitski, I. Petkova, A. Singh, W. J. Buma, R. P.
Thummel, J. Waluk, Angew. Chem., Int. Ed. Engl. 47, 6037 (2008).
Page 31
Panel Discussion
Page 32
Oral Communications
Oral Communications
Page 33
Oral Communications
Direct observation of sulfonyl azide excited state and its decay
processes by ultrafast time-resolved IR and UV-Vis spectroscopy
Jacek Kubicki
Adam Mickiewicz University, Faculty of Physics, Poznań, Poland, [email protected]
Recently the early stages of photolysis of acyl azides and phosphoryl azide were studied by
1-3
ultrafast spectroscopy. The mechanism of nitrene formation and Curtius rearrentment has
been investigated. It was shown that both singlet
nitrene and isocyanate are formed directly from the
1-3
S1 excited state of azide. These results motivated
us to study the photochemistry of sulfonyl azide with
ultrafast spectroscopy. 2-Naphthyl sulfonyl azide (2NpSO2N3) was chosen in this study as it has a
convenient chromophore for UV-vis excitation. In
addition, calculations predict that the singlet and
triplet states of 2-NpSO2N3, the singlet and triplet
states of nitrene 2-NpSO2N, and the pseudo Curtius
rearrangement photoproduct 2-NpNSO2 all have
relatively intense IR markers, which make this
compound an ideal target for ultrafast IR study.
Photolysis of 2-NpSO2N3 with 330 nm excitation
promotes 2-NpSO2N3 directly to the S1 state, which
-1
was observed at the 2080 cm by ultrafast IR
spectroscopy (Fig. 1) and in 350-650 nm spectral
range by ultrafast UV-vis spectroscopy. To our best
knowledge this is the first direct observation of the
S1 state of sulfonyl azides. It was found that internal
conversion is a major deactivation process of the S1
state while intersystem crossing brings only minor
contribution. The S1 state decays also to singlet
Fig.1 (a) Transient IR spectra produced by
nitrene
and undergoes concerted pseudo Curtius
photolysis of 2-NpSO2N3 in CCl4 (λexc=330
rearrangement. Singlet sulfonyl nitrene is short-lived
nm). (b) Transient kinetics observed at the
species and it decays to triplet nitrene via
2083 cm-1 (the S1 state decay) and at the
intersystem crossing. The assignments of species
2129 cm-1 (the ground state recovery).
detected experimentally are consistent with
quantum chemical calculations and matrix studies.
The project was performed in collaboration with Drs. Matthew S. Platz and Christopher M. Hadad’s research groups at the Chemistry Department of The Ohio State University.
[1] Kubicki, J.; Zhang, Y.; Wang, J.; Luk, H. L.; Peng, H.-L.; Vyas, S.; Platz, M. S. J. Am. Chem. Soc.
131, 4212 (2009)
[2] Kubicki, J.; Zhang, Y.; Vyas, S.; Burdzinski, G.; Luk, H. L.; Wang, J.; Xue, J.; Peng, H.-L.; Pritchina,
E. A.; Sliwa, M.; Buntinx, G.; Gritsan, N. P.; Hadad, C. M.; Platz, M. S. J. Am. Chem. Soc. 133, 9751
(2011).
[3] Vyas, S.; Muthukrishnan, S.; Kubicki, J.; McCulla, R. D.; Burdzinski, G.; Sliwa, M.; Platz, M. S.; Hadad, C. M. J. Am. Chem. Soc. 132, 16796 (2010)
Page 34
Oral Communications
2-(2-Pyridyl)pyrrole: coupling of photoinduced electron/proton
transfer with conformational changes
1
2
2
Michał Kijak , Wybren Jan Buma , Ivo van Stokkum , Jacek Waluk
1
1
2
Institute of Molecular Chemistry, University of Amsterdam
1-3
Intramolecular excited state proton transfer in 2-(2-pyridyl)pyrrole has been studied by
time-resolved spectroscopy techniques. Femtosecond/picosecond transient absorption and
emission measurements reveal the sequence of fast events that occur after photoexcitation.
The flow of electronic density from the pyrrole to the pyridine moiety is followed by proton transfer to the pyridine nitrogen. Due to large differences in excited state dipole moments between
the initial and final tautomeric forms, the barrier and rate of phototautomerization vary strongly
with solvent polarity. The tautomeric form is unstable and decays faster than it is formed, possibly by way of twisting (Fig.1). The ground state tautomeric species is detected and assigned on
the basis of the mirror relationship to the phototautomeric emission. Density functional theory
molecular modelling of the reaction in the ground and the excited state confirms the above
scheme and suggests that twisting in the excited tautomer can be active in the efficient radiationless transition.
Fig.1. Scheme of proton transfer cycle in 2-(2-pyridyl)pyrrole
[1] M. Kijak, A. Zielinska, C. Chamchoumis, J. Herbich, R. P. Thummel, J. Waluk, Chem. Phys. Lett.
400, 279 (2004)
[2] M. Kijak, Y. Nosenko, A. Singh, R. P. Thummel, J. Waluk, J. Am. Chem. Soc. 129, 2738, (2007)
[3] M. Kijak, Y. Nosenko, A. Singh, R. P. Thummel, B. Brutschy, J. Waluk, J. Mol. Struct. 844, 286,
(2007)
Page 35
Oral Communications
The ground- and excited-state double proton transfer in alloxazine
and some of its derivatives: Theoretical and experimental approach
1
1
1
2
3
Sikorski M. , Dobek K. , Hoffmann M. , Ferreira L.F.V. , Sikorska, E.
1
A. Mickiewicz University, Poznań, Poland, [email protected]
2
Universidade Técnica de Lisboa, Lisboa, Portugal
3
Poznań University of Economics, Poznań, Poland
Our recent work on excited-state double proton transfer (ESDPT) focussed on lumichrome =
7,8-dimethylalloxazine = 7,8-dimethyl-benzo[g]pteridine-2,4(1H,3H)-dione, a representative of
alloxazines. Acetic acid acts as a catalyst for the ESDPT reaction in lumichrome, as its own
[1,2]
structure remains unchanged upon ESDPT in e.g. acetic acid/lumichrome complex
, while
[3]
ESDPT in the lumichrome dimer changes the structure of both molecules . Quantummechanical calculations confirm that ESDPT in the lumichrome-acetic acid complex is a con[2,4]
, predicting proton transfer leading to an energy minimum (cation-anion pair)
certed process
[3]
in the lumichrome dimer .
The data obtained for a series of fourteen alloxazine derivatives, clearly indicate significant
substituent effects on the alloxazine photophysics. Thus, 6,7-dimethyl-alloxazine, 6-methylalloxazine, 7-methyl-alloxazine, and their respective 1-methyl substituted derivatives were chosen for the ESDPT studies. Such choice of molecules enabled to study the effect of the first
excited state configuration, (n, π)* over (π,π)*, modulated by the electronic structure of the
alloxazine and affected by the solvent choice, the effect of the hydrogen bond environment on
the ESDPT, and the solvent polarity effect. The ESDPT was structurally prevented in 1-methylsubstituted alloxazines, however, a clear effect of substituent position on ESDPT was noticeable comparing 6,7-dimethyl-alloxazine to 7,8-dimethylalloxazine. Steady-state and timeresolved fluorescence and absorption results were performed at 298K and 77K. Single-photon
timing was used to measure the emission lifetimes. These results confirm formation of an isoalloxazinic excited state via ESDPT catalyzed by a carboxylic acid molecule forming a hydrogenbonded complex with the parent alloxazine. Experimental results were supported by quantummechanical calculations: the calculated activation barrier in the excited state is much lower than
that in the ground state. Additionally, flash photolysis was used to explore ESDPT in triplet
states, with negative results.
1
1
References
[1] Sikorska, E., Khmelinskii, I. V., Prukala, W., Williams, S. L., Patel, M., Worrall, D. R., Bourdelande, J.
L., Koput, J., Sikorski, M. J. Phys. Chem. A 2004, 108, 1501.
[2] Sikorska, E., Khmelinskii, I. V., Hoffmann, M., Machado, I. F., Ferreira, L. F. V., Dobek, K.,
Karolczak, J., Krawczyk, A., Insinska-Rak, M., Sikorski, M. J. Phys. Chem. A 2005, 109, 11707.
[3] Sikorska, E., Khmelinskii, I. V., Kubicki, M., Prukala, W., Hoffmann, M., Machado, I. F., Ferreira, L. F.
V., Karolczak, J., Worrall, D. R., Krawczyk, A., Insinska-Rak, M., Sikorski, M. J. Phys. Chem. A 2006,
110, 4638.
[4] Sikorska, E., Koziolowa, A., Sikorski, M., Siemiarczuk, A. J. Photochem. Photobiol. A 2003, 157 (1),
5-14.
Page 36
Oral Communications
Photoactive titanium dioxide coatings on organic polymers
Rafał Sadowski, Wojciech Macyk
Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków, Poland
Nonsocomial infections also called “hospital acquired infections” are one of the major
problems of modern medicine. They contribute to mortality and morbidity thereby increasing
health care costs [1]. Course of infections can be different but most of them are related to the
infection through medical polymers. Currently, the most important trend is focused on the
design of materials with anti-infective properties. Many research programs are focused on the
modification of polymer surface by using additives and/or copolymerization processes in order
to change surface properties without changing the polymer in its bulk. In general, surface
treatments can be divided into three categories: chemical, thermal and electrical. The most
promising is modification by plasma induced in various gases. Such elctrical treatment allows
generation of surface radicals and ionic groups which improve film wettability and change
surface chemistry, opening a possibility of binding various antibacterial agents. Also some
photocatalytic coatings can be used as antimicrobial agents. Among others TiO2 shows a high
activity in photodynamic inactivation of bacteria with the benefits of its physical and chemical
stability, low toxicity, bio-compatibility and cheapness [2-4].
Two types of commercially available polyurethane foils (Bayer) were used in our
studies as supports for titanium dioxide films. Each foil was pretreated with various types of
plasma and covered with titanium dioxide thin film by spin- and dip-coating techniques. Also
other methods, involving no plasma activation, have been applied in synthesis of TiO2 layers.
Afterwards the films were photosensitized by titanium(IV) surface complexes formed upon
impregnation with catechol-like ligands [5]. The quality, involving stability and photocatalytic
activity of prepared films, were compared. The results of these tests will be presented and
discussed.
Acknowledgement
This study is a part of PhD work of RS within Interdisciplinary PhD-studies “Molecular
science for medicine” financed by Human Capital Operational Programme.
[1] G. Ducel, J. Fabry, L. Nicolle et al., Prevention of hospital-acquired infection, a practical guide, 2nd
edition (World Health Organization, Malta, 2002)
[2] W. Su, S. Wang, X. Wang, X. Fu, J. W, Plasma pre-treatment and TiO2 coating of PMMA for the improvement of antibacterial properties, Surface & Coatings Technology 205, 465-469 (2010)
[3] M.R. Sanchis, O. Calvo, O. Fenollar, D. Garcia, R. Balart, Characterization of the surface changes and
the aging effects of low-pressure nitrogen plasma treatment in polyurethane film, Polymer Testing 27,
75-83 (2008)
[4] S. Sartori, A. Rechichi, G. Vozzi, M. D’Acunto, E. Heine, P. Giusti, G, Ciardelli, Surface modification of a
synthetic polyurethane by plasma glow discharge: Preparation and characterization of bioactive
monolayers, Reactive & Functional Polymers 68, 809-821 (2008)
[5] W. Macyk, K. Szaciłowski, G. Stochel, M. Buchalska, J. Kuncewicz, P. Łabuz, Titanium(IV) complexes
as direct TiO2 photosensitizers”, Coord. Chem. Rev. 254, 2687-2701 (2010)
Page 37
Oral Communications
Photophysical and electrochemical features of semiconductors
modified with polynitriles
1
2
2
1,3
Marek Oszajca , Matteo Amelia , Alberto Credi , Konrad Szaciłowski
1. Photochemistry of Coordination Compounds and Bioinorganic Chemistry Group, Institute of
Chemistry, Jagiellonian University, Ingardena 3, 30-060, Kraków, Poland,
2. Dipartimento di Chimica ‘‘G. Ciamician’’, Universita di Bologna, via Selmi 2 - 40126 Bologna,
Italy
3. Faculty of Non-Ferrous Metals, AGH University of Science and Technology, A. Mickiewicza
30, 30-059 Kraków, Poland
[email protected]
O
P
Cyanocarbon acids synthesized by Middleton et al. in 1950s are derivatives of the well known
organic electron acceptor – tetracyanoethylene (TCNE) [1]. TCNE and its three derivatives were
CN
CN
examined: 1,1,2,3,3-pentacyanoprop-2-en-1-ide,
CN
NC
bis(tricyanoethenyl)-azanide
and
N
CN
NC
bis(tricyanoethenyl)diazanediide (Figure 1). IntenCN
NC
CN
CN
ded as a new class of pigments, these compounds
CN
CN
CN
CN
have found little attention in photoelectrochemistry. Their linear structure make them capable of
C
N
CN
CN
NC
N
reaching the surface of semiconducting quantum NC
CN
CN
CN
dot (QD) more easily than aromatic ring based
electron acceptors e.g. tetracyanoquinodimethane
(TCNQ). The reversible electrochemistry of TCNE
and its derivatives enhances the efficient quenP
P
ching of the QD excited state. In case of TCNE
O
P
O
O
new absorption band was formed, due to formation of charge-transfer complex between TCNE
and QD.
Further photoelectrochemical studies revealed
CdSe
that modifying QD surface with TCNE and its
derivatives significantly enhances generation of
the photocurrents. In addition, the direction of the
photocurrent could be switched from cathodic to
anodic and the other way round by application of
adequate
external
potential.
The
photoelectrochemical properties of those materials allow
construction of optoelectronic logic gates via the
Figure 1. TCNE and its derivatives modifyPEPS effect mechanism [2].
ing the CdSe surface
This work was supported by The Ministry of Science and
Higher
Education (grant
№
1609/B/H03/2009/36). M.O. thanks The Foundation for Polish Science for the MPD Programme
fellowship co-financed by the EU European Regional Development Fund.
P
P
O
O
O
P
O
P
P
O
P
O
O
O
P
O
P
O
P
P
[1] W. J. Middleton, E.L. Little, D.D. Coffman, V.A. Engelhardt, J Am Chem Soc. 80 (1958) 2795–806.
[2] A.K. Podborska, M.F. Oszajca, S.A. Gawęda, K.T. Szaciłowski, IET Circuits Devices Syst. 5 (2011) 103-14.
Page 38
Oral Communications
New optoelectronic logic devices based on surface-modified TiO2
1
Podborska A. , Szaciłowski K.
1,2
1
2
Faculty of Chemistry, Jagiellonian University, [email protected]
Faculty of Non-Ferrous Metals, AGH University of Science and Technology
Nowadays people require more and more powerful computing devices. Classical electronic
devices are, however, insufficient. One of the feasible solutions to this problem seems to be
application of molecular switching
devices.
Furthermore,
the
application of light as the information carrier may further improve
the performance of molecularscale devices. The most interesting materials, in point of view of
optoelectronics,
are
hybrid
materials showed photoelectrochemical photo-current switching
(PEPS) effect. This effect can be
defined
as
switching
of
photocurrent polarity on change
in photoelectrode potential and/or
incident light wavelength. This
effect was observed in some
Fig.1 The PEPS effect in TCNQ@TiO2 material.
surface-modified TiO2 materials
[1-4].
Combination of 7,7',8,8'-tetracyanoquinodimethane (TCNQ) which is a good one-electron
acceptor and titanium dioxide (TiO2) - a very good semiconductor results a new hybrid material
with unique properties. Photoelectrodes prepared from this hybrid material exhibit the PEPS
effect. Changing the wavelength or the photoelectrode potential easily switches the direction of
photocurrent. At positive polarization of the photoelectrode only anodic photocurrent are observed as it can be expected for n-type semiconductor. At more negative potentials only cathodic photocurrent are observed.
Photoelectrochemical and spectroscopic studies allowed the elucidation of the mechanism
of photocurrent switching. This mechanism is based on photoinduced electron transfer processes from TCNQ molecule to TiO2 particle. Geometry and electronic structure calculations
using DFT method confirmed this mechanism.
Photoelectrochemical properties of TCNQ@TiO2 materials seems to be suitable to construct
the simple logic gates or more advances logic devices, such as demultiplexer [5-7].
[1] S. Gawęda, G. Stochel, K. Szaciłowski, Chem. Asian J. 2, 580-590 (2007)
[2] K. Szaciłowski, W. Macyk, M. Hebda, G. Stochel, ChemPhysChem, 7, 2384-2391 (2006)
[3] K. Szaciłowski, W. Macyk, W. Chimia, 61, 831-834 (2007)
[4] S. Gawęda, G. Stochel, K. Szaciłowski, J. Phys. Chem. C, 112, 19131–19141 (2008)
[5] A. Podborska, K. Szaciłowski, Austr. J. Chem. 63, 165-168 (2010)
[6] J. Mech, R. Kowalik, P. Kwolek, A. Podborska, K. Szaciłowski, Austr. J. Chem. 63, 1330-1333 (2010)
[7] S. Gawęda, R. Kowalik, P. Kwolek, W. Macyk, J. Mech, M. Oszajca, A. Podborska, K. Szaciłowski
Isr. J. Chem., 51, 36–55 (2011)
Page 39
Oral Communications
The synthesis and optical properties of novel coumarins
1
1
Tasior M. , Gryko D. T.
1
Institute of Organic Chemistry, Polish Academy of Sciences, [email protected]
One of the major objectives in the field of artificial photosynthesis is to create synthetic complexes that are able to convert and store light energy [1]. Numerous artificial photonic assemblies based on porphyrin architectures have been designed with the goal of achieving efficient
energy and charge transfer. Corroles, one carbon short analogues of porphyrins, have recently
emerged as an independent area of research. Their coordination chemistry, synthesis, chemical
transformations, electrochemistry and other properties have been studied in great detail [2]. In
contrast to porphyrins, the photophysics of corroles has scarcely been studied [3].
As a part of broader program in the chemistry of corrole containing assemblies, we have
created covalently linked corrole-coumarin dyads. Coumarins were chosen because of their
excellent and well documented photochemical and photophysical behavior. Herein, we report
the results of our synthetic and photophysical studies.
C 6 F5
O
F
NH
HN
NH
N
F
O
O
F
O
O
F
C 6 F5
NEt2
[1] D. Gust, T. A. Moore, A. L. Moore, Acc. Chem. Res. 34, 40 (2001).
[2] D. T. Gryko, M. Tasior, B. J. Koszarna, J. Porphyrins Phthalocyanines. 7, 239 (2003).
[3] F. D’Souza, R. Chitta, K. Ohkubo, M. Tasior, N. K. Subbaiyan, M. E. Zandler, M. K. Rogacki, D. T.
Gryko, S. Fukuzumi, J. Am. Chem. Soc. 130, 14263 (2008).
Acknowledgment:
Financial support of our work from the Foundation for Polish Science (Grant number
TEAM/2009-4/3) is gratefully acknowledged.
Page 40
Oral Communications
Radiationless Deactivation of Subpyriporphyrins
1
1
1
Pawlicki, M. , Myśliborski, R. , Latos-GraŜyński, L.
2
2
2
Kim, K.-S., Lim, J.-M., Kim, D,
1
Department of Chemistry, University of Wroclaw, [email protected]
2
Department of Chemistry, Yonsei University
Boron(III) subporphyrins i.e. 1, present features characteristic for aromatic macrocycles, with
[1]
typical spectroscopic properties and rather high S1 → S0 emission. In contrast to the proper[2]
ties of 1, subpyriporphyrin 2, a very first subporphyrin (a homologue of [14]triphyrin) without a
centre boron(III), does not present such behaviour. It’s character remains non-aromatic as the
presence of pyridine blocks the delocalization. The absence of boron(III) in the centre leaves
the inside proton giving a unique donors set with three, ‘unblocked’ nitrogens observed for
smaller macrocycles. These free nitrogens makes possible a systematic exploration of the pro-
Figure 1. Subporphyrins
[3]
tonation and its influence on the spectroscopic behaviour. In contrast to 1, the absence of
boron(III) in 2 creates an opportunity for observation of spectroscopic properties for subporphyrin skeleton where NH tautomerization within the coordination cavity is possible. The results of
such studies will be presented and discussed.
[1] Y. Inokuma, Z.-S. Yoon, D. Kim, A. Osuka J. Am. Chem. Soc. 129, 4747 (2007)
[2] R. Myśliborski, L. Latos-GraŜyński, L. Szterenberg, T. Lis Angew. Chem. Int. Ed. 45, 3670 (2006)
[3] K.-S. Kim, J.-M. Lim, R. Myśliborski, M. Pawlicki, L. Latos-GraŜyński, D. Kim J. Phys. Chem. Lett. 2,
477 (2011)
Page 41
Oral Communications
Photon-induced and spontaneous transformations of the structure
of cytosine molecule
1
1
2
M. J. Nowak , L. Lapinski , I. Reva and R. Fausto
1
2
Institute of Physics, Polish Academy of Sciences, Warsaw, Poland, [email protected]
2
Department of Chemistry, University of Coimbra, Coimbra, Portugal
Excitation of cytosine isolated in an Ar matrix with narrowband UV radiation promotes
selective transformations into its rare tautomers. Laser light UV, λ=314 - 312 nm, irradiation of
the low-temperature matrix containing cytosine monomers resulted in syn-anti photoisomerization between the two imino-oxo forms (IO1↔IO2), whereas the substantially more
populated amino-hydroxy (AH) and amino-oxo (AO) forms stayed intact. Subsequent irradiation
with shorter-wavelength UV, λ=311 nm, laser light led to two concomitant phototautomeric
processes consuming the amino-oxo isomer: (i) oxo→hydroxy hydrogen-atom transfer converting the amino-oxo form into the amino-hydroxy tautomer, AO → AH; (ii) amino→imino hydrogen-atom transfer converting the amino-oxo form into the imino-oxo isomers AO → IO [1].
H
N
H
NIR / IR
H
N
N
N
7034 cm-1
O
N
H
AH1
tunneling
H
O
H
H
λ > 311 nm
7013 cm-1
N
AH2
N
λ > 311 nm
N
O
H
N
N
H
O
H
H
N
N
λ > 314 nm
H
O
N
N
N
H
H
H
AO
IO1
IO2
Fig. 1. Hydrogen-atom-transfer processes leading to transformation between the isomeric forms of cytosine.
Narrow band near-IR laser light was used to excite one of the conformers of amino-hydroxy
tautomer of cytosine to the vibrational state corresponding to the overtone of the OH stretching
vibration. Such excitation promoted torsion of the OH group and led to the change of conforma-1
tional form of the hydroxy tautomer. For cytosine monomers, NIR laser irradiation at 7013 cm
-1
led to AH1 → AH2 transformation while irradiation at 7034 cm induced reverse transformation
AH2 → AH1 of the two conformers [2]. It was demonstrated that other forms of cytosine (aminooxo and imino-oxo) are not affected by NIR irradiation.
Upon broadband irradiation with the beam from the IR source of FTIR spectrometer the
population ratio of the two amino-hydroxy conformers changed towards a ratio corresponding to
the photostationary state. Evolution of conformer population ratio towards the photostationary
ratio occurred independent of the initial ratio of conformers, which could be prepared by a
narowband-NIR-induced population shift in favor of one of the forms [3].
Moreover, spontaneous tunneling conversion of the higher-energy conformer AH2 into a
lower-energy form AH1 was observed for cytosine isolated in a low-temperature argon matrix
kept in the dark. This process was slow and occurred in a time scale of days [3].
[1] L. Lapinski, I. Reva, M. J. Nowak and R. Fausto, Phys. Chem. Chem. Phys. 13, 9676 (2011).
[2] L. Lapinski, M. J. Nowak, I. Reva, H. Rostkowska and R. Fausto, Phys. Chem. Chem. Phys. 12,
9615 (2010).
[3] I. Reva, M. J. Nowak, L. Lapinski, and R. Fausto, Phys. Chem. Chem. Phys. submitted (2011).
Page 42
Oral Communications
Electron transfer and photodissociation in a spirocyclic
bichromophoric molecule
1
1
2
3
1
Karolak-Solarska E., Kijak M., Fita P., Nowacki, J., Karpiuk J.
1
Institute of Physical Chemistry, Polish Academy of Sciences; [email protected]
2
Faculty of Physics, University of Warsaw
3
Faculty of Chemistry, University of Warsaw
3
The linkage of two cyclic systems by a central tetrahedral carbon atom (sp ) results in formation of spiro compounds. In spite of the mutually perpendicular orientation of the two πelectronic systems, both subunits can interact via through-space 3-D spiroconjugation under the
condition that the MOs of both
N(CH3 )2
(H 3 C)2 N
N(CH3 )2
(H 3 C)2 N
fragments are antisymmetric with
respect to the two perpendicular
bisecting planes.
O
O
In CVLB, a spirocyclic analogue
of crystal violet lactone
O
(H 3 C)2N
(CVL), the spiroconjugation maniCVLB
CVL
fests itself by non-additivity of
electronic absorption spectra of
the structural subunits. Quantum chemical modeling confirms the presence of spiroconjugation
between antisymmetric HOMOs localized on the two halves of CVLB, resulting in formation of
new orbitals spanning over the entire molecule and leading to new electronic transitions.
(H 3 C)2 N
O
The two perpendicularly oriented subunits of CVLB, 6-dimethylaminophtalide (6-DMAPd)
and bis-N,N-dimethylaminofluorene (bDMAF), when considered as independent molecules, are
highly efficient fluorophores with comparable energies of their S1 states. In contrast to CVL
displaying in non-polar solvents efficient fluorescence from the S1 state localized on 6-DMAPd
[1, 2], rigid CVLB undergoes very fast radiationless deactivation [3]. The aim of our work was to
elucidate the impact of structurally induced spiroconjugation on CVLB photophysics and the role
of excited state energetics in the enhanced excited state nonradiative deactivation.
Transient absorption measurements in the low ps domain reveal rapid relaxation to the fluorescent CT state (as in CVL) and formation of a dark state that is tentatively assigned to a ringopen form (Z) of CVLB. At present we can not determine if the Z form is populated diabatically
or adiabatically – similarly as in rhodamine lactones [4]. The decays of the CT state and of the
dark state are not kinetically correlated, indicating that branching into the two deactivation pathways occurs only before the vibronic relaxation of the primarily excited FC state is completed.
[1] J. Karpiuk, J. Phys. Chem. A 108, 11191 (2004)
[2] U. Schmidhammer, U. Megerle, S. Lochbrunner, E. Riedle, J. Karpiuk, J. Phys. Chem. A 112, 8487
(2008)
[3] J. Karpiuk, E. Karolak-Solarska, J. Nowacki, Phys. Chem. Chem. Phys. 12, 8804 (2010)
[4] J. Karpiuk, Z. R. Grabowski, F. C. De Schryver, J. Phys. Chem. 98, 3247 (1994)
Page 43
Oral Communications
Excited state deactivation processes in 3-aminoflavone
1
2
1
A. Szemik-Hojniak , I. Deperasinska , Ł. Wiśniewski
1
Faculty of Chemistry, University of Wroclaw, Joliot-Curie 14 st; 50-383 Wroclaw (Poland).
E-mail: [email protected]
2
Institute of Physics, Pol. Acad. of Sciences, Al.Lotników 32/46, 02-668 Warsaw (Poland).
Flavones, are the sub group of flavonoids – widely distributed group of naturally occurring
biologically active compounds, demonstrating antibacterial, anticancer, cytostatic and other
important therapeutic properties [1,2].
In the excited state they show a complex photophysical characteristics like the excited state
intramolecular proton (ESIPT) or electron transfer processes found in 7- , 5- or 3hydroxyflavones [3]. In either of them the role of the solvent polarity is highlighted. In studied
here 3-aminoflavone (3-AF, Figure 1), the N-H…O hydrogen bonding geometry is unfavorable
FC
for the ESIPT to occur and the S0 → S1 (ππ*) transition demonstrates a partial CT nature.
30000
FC
S1 (4.58 D)
25000
2211 cm-1
10000
23087 cm-1
15000
27231 cm-1
-1
energy [cm ]
S1 (4.74 D)
20000
µ(S1)
µ(S0)
5000
0
FC
S0 (2.72 D)
S0 (3.04 D)
1933 cm-1
Fig.1.Molecular structure and energetics of 3AF molecule.
The transfer of charge occurs between the 62 π HOMO orbital of the amino group and 63 π*
LUMO orbital of the chromon ring. Its dipolar changes result in batochromically shifting emission
-1
maxima with the solvent polarity increase (Stokes shift value in THF is 6489 cm ). Interesting
experimental observations combined with TD DFT calculations revealed that in apolar and
weakly polar solvents the excited state deactivation of 3AF proceeds through the radiative
fluorescence and nonradiative intersystem crossing (ISC) paths while in the polar media, the
internal conversion (IC) turns out to be the dominant process.
This work was supported by the following grants: Min. of Sci. and High Educ.(Poland) Nr N
N204 131338; ICMCM-Warsaw (G32-10) and WCSS-Wroclaw (G-61).
[1] B.Hallivel. et al., J. Am. J. Clin. Nutr. 81 (2005) 268S
[2] B.Kośmider, R., Osiecka, Drug. Dev. Res. 63 (2004) 200
[3] P.K. Sengupta, M. Kasha, Chem. Phys. Lett. 68 (1979) 382.
Page 44
Oral Communications
Investigation of the bi-molecular energy transfer processes
in liquid solutions
1
1
Jędrzej Solarski , Gonzalo Angulo , Andrzej Kapturkiewicz
1,2
1
Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland, [email protected].
2
Institute of Chemistry, Faculty of Sciences, University of Siedlce,3 Maja 54, 08-110 Siedlce,
Poland
Energy transfer reactions are one of the important photoinduced processes to due their crucial
role in the early stages of photosynthesis and potential technological applications. Despite that
the general understanding of such phenomenon in liquid media is still lacking [1, 2]. It is especially true for a proper kinetic description in terms of reactants and medium properties. This
arises from the scarcity of experimental data due to the specific requirements needed to be
fulfilled by the studied physico-chemical model systems in order to reveal the relevant kinetic
information with enough large precision.
By investigating energy transfer processes between excited triplet states of luminescent iridium
complexes and organic energy acceptors most of the common drawbacks can be overcame
that allows for quantitative estimation of the kinetics parameters of the reversible energy transfer processes (REN) from analysis of bi-exponential decays of the donor luminescence [3]. The
applied approach can be also proposed as an alternative method for determining molecular
triplet state energies and lifetimes that are sometimes difficult to measure in liquid media.
[1] K. Sandros, Acta Chem. Scand., 18, 2355, (1964)
[2] V. Balzani, F. Bolletta, F. Scandola, J. Am. Chem. Soc., 102, 2152, (1980)
[3] J. Solarski, G. Angulo, A. Kapturkiewicz, J. Photochem. Photobiol. A Chemistry, 218, 58-63, (2011)
Page 45
Oral Communications
Supersonic jet spectra and ab initio modelling of S0→S1 transition
of anthranilic acid molecule
1
2
2
Kolek P. , Andrzejak M. , Najbar J.
1
Institute of Physics, Rzeszów University, [email protected]
2
Faculty of Chemistry, Jagiellonian University
Laser induced fluorescence (LIF) excitation spectra for the S0→S1 transition of anthranilic
acid molecule as well as the spectra of the molecules deuterated in the substituent groups
(COOD, ND2) was investigated. In addition to the LIF spectrum of pristine molecule[1], three
spectra of partially deuterated samples were recorded, for isotopic exchange ratio ca. 25%,
50% and 80%[2] in the substituent groups (Fig.1).
The deuteration shifts of vibrational bands well correlate with the values computed with ab
initio CC2 quantum mechanical method as well as time-dependent perturbation TDDFT(B3LYP) method [3]. The intramolecular hydrogen bond is significantly stronger in the S1
state than in the ground state. Additionally, bond lengths and angles in the aromatic ring, within
the substituents and between the ring and the substituents undergo significant changes and
they induce the presence of strong fundamentals in the excitation spectrum.
The blue-shift of the 00 transition due to the isotopic substitution (COOD, ND2), is equal to
–1
47 cm . This relatively large value is caused primarily by a significant decrease of the N–H
stretching frequency associated with the increase of strength of the intramolecular hydrogen
bond upon the electronic excitation. The deuteration shifts of the 00 band in the S0→S1 transition can be interpreted of in terms of the zero point energies (ZPE) of the relevant electronic
states. These corrections include the contribution of the ZPE for the inversion mode of the isotopically substituted amino group (NH2, NHD, NDH and ND2), in addition to the contribution of
harmonic vibrations. This fine effect was modelled using the one-dimensional double-well potential[2].
Fig.1 LIF spectra of anthranilic acid prtially deuterated in the substituent groups ordered according to increasing isotopic exchange ratio: 0% (bottom), 25%, 50%, and 80% (top). Band position with respect to the
electronic origin for pristine molecule (v -v00 NH2 COOH where v00 NH2 COOH = 28 591 cm-1) is presented.
[1] P. Kolek, S. Lesniewski, K. Pirowska, J. Najbar, J. Mol. Spectr. 249(2) (2008) 100
[2] P. Kolek, S. Leśniewski, M. Andrzejak, M. Góra, P. Cias, A. Węgrzynowicz, J. Najbar, J. Mol. Spectr.
264(2) (2010) 129
[3] S. Lesniewski, P. Kolek, K. Pirowska, A.L. Sobolewski, J. Najbar, J. Chem. Phys. 130 (2009) 054307–1
Page 46
Oral Communications
Electron localization function, noncovalent interactions analysis
and other theoretical tools in photochemistry
Kasprzycki P., Fita P., Radzewicz Cz.
Institute of Experimental Physics, University of Warsaw, HoŜa 69, Poland
Numerical solutions of the Schrödinger equation can nowadays be obtained for reasonably
large organic and organometallic molecules with useful accuracy using approximate ab initio or
DFT methods [1]. These approximate solutions are also available for porphycene which is an
important chromophore [2]. Porphycene and its derivatives show
useful properties for material
sciences and are also considered
excellent photosensitive media for
applications in photodynamical
therapy of cancer [3, 4]. Several
papers have discussed the energy structure and dynamic aspects of hydrogen transfer in this
systems [5-7]. We report on the
results of NCI and ELF analysis two theoretical tools based on
Bader approach [8, 9] - performed
Fig.1. NCI analysis for 9,10,19,20-tetramethylporphicyne (CMPC). for four symmetrically substituted
porphycene derivatives. We have
carried out DFT and TDDFT calculations at the level of B3LYP/6-311(d,p). These calculations were followed by NCI and topological ELF analysis. Calculations showed the correlation between value of reduced density
gradient and time of proton transfer in the examined systems. We show that noncovalent interactions analysis is useful not only for detection of strong hydrogen bounds and weak van der
Waals interaction but also for comparing power of hydrogen bounds in the four investigated
compounds. This can be significant for understanding the mechanism of double hydrogen transfer between inner nitrogen atoms.
[1] P. Hohenberg, W. Kohn, Phys. Rev. B 1964, 136, 864 - 871;
[2] D. Sanchez-Garcia, J. L. Sessler, Chem. Soc. ReV. 2008, 37, 215.
[3] Denisov, I. G.; Makris, T. M.; Sligar, S. G.; Schlichting, I. Chem Rev 2005, 105, 2253;
[4] J. C. Stockert, M. Canete, A. Juarranz, A. Villanueva, R. W. Horobin, J. I. Borrell, J. Teixido, S.
Nonell, Curr. Med. Chem. 2007, 14,997;
[5] Ł. Walewski, J. Waluk, B. Lesyng, J. Phys. Chem. A, 2010, 114, 2313–2318;
[6]M. Gil, J. Waluk J. Am. Chem. Soc. Vol. 129, No. 5. 2007;
[7] A. D. Quartarolo, S. G. Chiodo, N. Russo, J. Chem. Theory Comput., 6(10), 3176-3189;
[8] E. R. Johnson, S. Keinan, , J. Contreras-García, R. Chaudret, J-P Piquemal, D. Beratant, W. Yang,
J. Chem. Theo. and Comp., 2011, 25;
[9] A. D. Becke, K. E. Edgecombe, J. Chem. Phys. 1990, 92, 5397;
Page 47
Oral Communications
Substituent effect on the energetical landscape of the molecular
photo-switch
1
1
Rode M. F. and Sobolewski A. L.
1
Institute of Physics, Polish Academy of Sciences, [email protected]
Molecular switches enable the storage of information on a molecular level, and their application
in nanotechnology, biomedicine, and computer chip design. The molecular system which may
serve as a molecular switch must posses two stable forms which may be switched by an electric
filed, chemical reaction or optical excitation.
In our investigation we are searching for molecular photo-switches
which operate on the Excited State
Intramolecular
Proton
Transfer
(ESIPT) [1,2,3,4]. The switching process involves the long-range transfer
of a proton which is picked up by a
„molecular crane” (C) at the donor site
due to optical excitation, and delivered to the acceptor site of the system by rotation of the crane. The
reversibility of the switch is guaranteed by the ESIPT mechanism conditions, which are: (i) photochromism of
the system and (ii) a barrierless access on the potential-energy surface
(PES) of the S1 state to the S1-S0
conical intersection (CI) which is
Fig. 1. Photophysical scheme of the molecular photo-switch
common for both photochromic forms.
In our theoretical study we have chosen two systems: 7-hydroxy-quinoline (7HQ) and 3hydroxy-picolinic acid (3HPA) as the molecular frames of the switch, as they may posses two
isomeric forms due the presence of two distinguishing hydrogen-donor/acceptor centers: O and
N atoms, being able to donate the hydrogen atom to the crane [3].
We have investigated several potential crane molecules such as carbaldehyde, pyridine,
oxazine and oxime being attached at the position 8’ of the 7HQ frame, as well as a carboxylic
group present in the picolinic acid, and searched for appropriate side groups (R) which, substituted at the given position, would improve the energetical landscape of the molecular system
[4], see Fig. 1.
Our study shows how the substituent effect exerts the influence on the energetical landscape
of the excited state and may be used in practice to search for materials of desired energetical
and optical properties.
[1] A. L. Sobolewski, Phys. Chem. Chem. Phys., 10, 1243 (2008).
[2] C. Benesch, M. F. Rode, M. Cizek, R. Hartle, O. Rubio-Pons, M. Thoss, and A. L. Sobolewski, J. Phys.
Chem. C, 113, 10315 (2009).
[3] L. Lapinski, M. J. Nowak, J. Nowacki, M. F. Rode, and A. L. Sobolewski, Chem. Phys. Chem., 10, 2290
(2009).
[4] M. F. Rode, A. L. Sobolewski, J. Phys. Chem. A, 114, 11879 (2010).
Page 48
Posters
Posters
Page 49
Posters
Superalkalies forming stable molecules with electron acceptors
1
2
Anusiewicz I. , Freza S.
1
2
The Na2X superalkali molecules (X=SH, SCH3, OCH3, CN, and N3) were found to be capa+
–
ble of forming stable [Na2X] [Y] salts with the species exhibiting various electron affinities
(Y=MgCl3, Cl, NO2). The dipole
moments, polarizabilities and
first-order hyperpolarizabilities
of the Na2XY ionic salts were
calculated and discussed. It
was found that the Na2XNO2
molecules
possess
the
extraordinary large values of
anisotropy of polarizabilities (in
-24
the 15.5-28.2×10 esu range)
and
the
first-order
hyperpolarizbilities (spanning
-30
the 597.8-1295.7×10
esu
range).
Fig.1 The MP2/6-311++G(d,p) equilibrium structure of Na2N3NO2
and the first –order hyperpolarizability
Page 50
Posters
Photodegradation of reactive azo dyes by advenced oxidation
processes
1
1
2
1
Brzeska M. , Perkowski J. , Blus K. , Szadkowska-Nicze M.
1
Institute of Applied Radiation Chemistry, Technical University of Łódź, ,
ul.Wróblewskiego 15, 93-590 Łódź, Poland,
2
Institute of Polymer & Dye Technology, Technical University of Łódź,
ul. Stefanowskiego 12/16, 90-924 Łódź, Poland
Reactive azo dyes represent the dominant class of synthetic colorants employed in textile
industry. They are produced in large amounts and released to the environment during dyeing
process. Although, wastewater released by textile industries contains azo type reactive dyes at
low concentration, they are resistant to biological degradation. Advanced Oxidation Processes
(AOPs) are efficient novel methods useful to accelerate the non-selective oxidation and thus the
destruction of a wide range of organic substances resistant to conventional technologies. In
AOPs, generally reactive, strongly oxidizing •OH radicals play the main role in destruction of the
dye molecules.
The aim of our work was to study the possibility of using AOPs to decolorize of reactive dyes
in aqueous solutions. We investigated photooxidation in air, (UV/air), in oxygen, (UV/O2), and
ozone, (UV/O3), atmosphere, combined methods with ozone and hydrogen peroxide
2+
(UV/O2/H2O2, UV/O3/H2O2) and photo-Fenton (UV/H2O2/Fe ) process for four reactive azo dyes
(Yellow BK-221, Red BK-230, Violet BK-253 and Black RB5). Low-pressure Hg lamp (15W) was
-1
used as a source of UV light. Decolorization of dyes solutions (100 and 200 mg L ) was observed spectrophotometrically by Perkin Elmer Lamda 750 spectrophotometer in UV-VIS range
190-800 nm. Progress of the photo-Fenton reaction was observed by means of chemical oxygen demand (COD) analysis.
It was found that decolorization of reactive azo dyes in aquoeous solutions depend on structure of dye molecule, solution concentration and AOPs version. The dyes solutions were easily
decolorized in O3 atmosphere, (UV/O3), (UV/O3/H2O2), and the lowest decolorization was observed in air. The decolorization rate of Black RB 5 solutions in all AOPs versions was similar.
Decolorization degree of this dye was in range 92-98% for UV/air and UV/O3, respectively. The
greatest differences in decolorization degree were observed in the case Red BK-230: 47% and
98% for UV/air and UV/O3, respectively. The photo-Fenton oxidation was poor for all dyes: .
reduction of COD was lower than 22%.
Page 51
Posters
Spectral and photophysical properties of individua formed by
selected photochromic Schiff bases in the ground and excited
states.
Filipczak K., Maciejewski A.
Faculty of Chemistry, Adam Mickiewicz University, Poznań
[email protected]
Schiff bases have been intensely studied because of the occurrence of excited state intramolecular proton transfer process (ESIPT, of great importance in nature) their photochromic
properties and numerous applications. Their structure implies that at a few sites the distribution
of electron density and geometry of the molecule can change as a result of excitation. Schiff
bases can occur in the form of enol and keto tautomers, each of them can occur as two syn-anti
or cis-trans isomers, and each of them can form a few conformers (rotamers). Schiff bases can
-5
3
form dimer even at very low concentrations (~10 mol/dm ) and greater aggregates [1].
The hitherto studies of these compounds have been performed by steady state and timeresolved absorption and emission spectrometers [2]. In such conditions the absorbance measured is a sum of absorptions of all individua present in a sample, similarly as the emission, so it
was impossible to reliably identify these individua. As the compound studied was used at very
-4
-5
3
low concentrations (10 – 10 mol/dm ) it was assumed that the sample contains exclusively
single molecules of Schiff bases.
Presented results were obtained by using HPLC-Abs-Em system consisting of UPLC® (or
HPLC) apparatus directly coupled with a photodiode spectrophotometer (acting also as
an absorption detector) and a highly sensitive spectrofluorometer (acting also as an emission
detector).
The use of HPLC-Abs-Em method, after adjustment of the measuring parameters, permits isolation of all individua present in the sample and their separation from impurities. If complete separation is not possible, this method enables the choice of the optimum parameters for measurements by conventional methods (e.g. λwzb, λem for measurements of emission or emission excitation spectra). At these optimum conditions, the influence of impurities can be eliminated or
substantially limited and control. Thus it is possible to examine what are the spectral and photophysical properties of individua formed by aromatic photochromic Schiff bases.
[1] R.S. Becker, Ch. Lenoble, A. Zein J. Phys. Chem. 91 (1987) 3517
[2] M. Ziolek, G. Burdzinski, K. Filipczak, J. Karolczak, and A. Maciejewski, Phys. Chem. Chem. Phys. 10
(2008) 1304
Page 52
Posters
SERS studies of porphycene
1
Sylwester Gawinkowski , Jacek Waluk
1
1
Rapid development of Surface-Enhanced Raman Spectroscopy (SERS) techniques is stimulated by prospects of applications in such fields as ultrasensitive detection, down to the single
molecule limit, biomedical diagnostics, or molecular imaging. Understanding the mechanisms of
SERS requires experiments in which the parameters relevant for the enhancement are varied in
a systematic way. For instance, different surface materials/morphologies can be tried for the
same chromophore, or, vice versa, a series of appropriately modified molecules can be studied
for the same support.
Porphyrin (PR) and its two structural isomers, porphycene (PC) and tetraazaannulene (TAA)
were selected as probes. These molecules are similar in the geometry of the inner cavity, but
significantly differ in spectroscopic properties. The investigations of both porphyrin, wellknown
as a “pigment of life”, and porphycene isomers, already shown to be very promising candidates
for phototherapeutic agents, are a subject of much study due to the importance for fundamental
research. The choice was justified by the fact that these molecules have been characterized by
methods of vibrational and electronic spectroscopy in our group [1,2]. These compounds are not
toxic, thus their single molecule applications in biology and medicine seem to be promising in
the future.
In this communication, we report on the SERS spectra of PC. The strategy is to monitor possible changes in the spectral positions and relative intensities in the SERS spectra, caused by the
proximity of active metal surface. In particular, we focus on the symmetry of the probed modes,
with the goal of analysing the relationship between the orientation of the probed chromophore
and its orientation with respect to the active surface.
PR
PC
TAA
[1] Gawinkowski, S; Eilmes, J; Waluk, J., J. Mol. Struct., 976, 215 (2010)
[2] Gawinkowski, S; Walewski, Ł; Vdovin, A; Slenczka, A; Ford, S; Johnson, M; Lesyng, B; Waluk, J; in
preparation
This work was supported by the European Union within European Regional Development Fund, through grant Innovative
Economy (POIG.01.01.02-00-008/08).
Page 53
Posters
Spectral and photophysical properties of
(E)-N-(alkyl-carbonyl-alhoxy)-2’(4’)-hydroxy-4-stilbazolium halides.
1
1
Gierszewski M., Prukała D., Sikorski M.
A. Mickiewicz University, Grunwaldzka 6, 60-780 Poznań E–Mail: [email protected]
(E)-2’(4’)-hydroxy-4-stilbazolium halides are composed by a donor group (hydroxy group)
and an acceptor group (substituted pyridinum moiety), connected by an ethylene bridge, possessing an extended conjugated π-electronic system [1]. N-substituted derivatives of (E)azastilbenols – quaternary stilbazolium salts, belonging to the hemicyanine class of compounds,
have a wide range of applications. Quaternary stilbazolium salts show a very strong antimicrobial acitivity, therefore they may be used as cosmetic preservatives. Indeed, we have previously
found that derivatives of (E)-azastilbenols are active against various species of fungi, including
corilus varsicolor, Gleophyllum trabeum, Paria placeuta etc. [2-3]. Stilbazolium dyes can also be
used as photosensitizers in photodynamic and photodiagnosis therapy (PDT and PDD) [4-5],
liquid crystals in non-linear optics [6], sensitizers in colour photography [7] and fluorescence
probes for monitoring free radical polymerization processes [8].
Spectrophotometric analysis
Stilbazolium dyes display negative solvatochromism, because the ground state is more stabilized by polar solvents than the excited state and their dipole moment is smaller in the excited
state than in the ground state.
Spectrofluorimetric analysis
Spectrofluorimetric analysis (emission, excitation specta; quantum yield; Stokes shifts)
shows, that the excited state of quaternary stilbazolium salts decay by non-radiative processes
in protic solvents.
Protonation / deprotonation equilibrium
We found that the protonated form of studied quaternary stilbazolium salts showed one
band, with the absorption maximum dependent on pH. The protonated form at acid pH had the
absorption maximum at ca. 375nm for compound 1 and at ca. 400nm for compound 2. The
respective deprotonated forms absorbed at 450 and 480 nm.
References
[1] D.Prukala, W.Prukala, I.Khmelinskii, M.Sikorski, Physical Chemistry Chemical Physics 13 (2011) 69506960.
[2] E.Wyrzykiewicz, A.Blaszczyk, B.Kedzia, Farmaco 55 (2000) 151-157.
[3] E.Wyrzykiewicz, A.Lapucha, K.Golankiewicz, S.Kucharski, J.Krysinski, Pharmazie 36 (1981) 407-410.
[4] D.Frackowiak, A.Waszkowiak, H.Maikowski, R.M.Ion, J.Cofta, K.Wiktorowicz, Acta Biochimica Polonica
48 (2001) 257-269.
[5] E.Staskowiak, A.Dudkowiak, I.Hanyz, K.Wiktorowicz, D.Frackowiak, Journal of Photochemistry and
Photobiology A-Chemistry 163 (2004) 127-134.
[6] C.Bosshard, F.Pan, M.S.Wong, S.Manetta, R.Spreiter, C.Z.Cai, P.Gunter, V.Gramlich, Chemical Physics
245 (1999) 377-394.
[7] L.G.S.Brooker, F.L.White, R.H.Sprague, Journal of the American Chemical Society 73 (1951) 10871093.
[8] J.Paczkowski, D.C.Neckers, J Polymer Science Part A 31 (1993) 841-846
Page 54
Posters
2-Chlorophenol photooxidation using meso-tetraphenylporphyrin
immobilized into polyurethane nanofabrics
1
2,3
1
Gmurek M. , Mosinger J. , Miller J.S.
1
Faculty of Process and Environmental Engineering, Technical University of Lodz,
2
Faculty of Science, Charles University in Prague,
3
Institute of Inorganic Chemistry, v.v.i., Academy of Sciences of the Czech Republic,
The photodegradation of the 2-chlorophenol (2-CP), belonging to the family of endocrine
disrupting compounds was studied. The reaction was performed in the aerated aqueous
solutions using meso-tetraphenylporphyrin (TPP) as a sensitizer. Porphyrins are efficient
sensitizers for singlet oxygen generation and play an important role in the photodynamic
therapy, synthesis of fine chemicals and photodegradation of water pollutants. The use of
immobilized sensitizers has several advantages, among other the problems of sensitizer
separation from the reaction mixture can be avoided and the reusability of the photosensitizer
can be realized. The literature on this topic is rather scarce and research are focused mainly on
water-soluble porphyrins or metalloporphyrins [1]. In this study polymeric polyurethane
nanofabrics prepared by the electrospinning method were used as a carrier for the studied
sensitizer.
The reactions were conducted in semicontinuous system using xenon arc lamp simulating
solar radiation. The influence of various parameters on the reaction course were investigated,
such as: 2-CP and oxygen concentration, pH of the reaction solution and the multiple-usestability of the immobilized sensitizer. The participation of molecular singlet oxygen in the
photooxidations was confirmed using indirect methods using sodium azide as a physical
1
quencher and imidazole as a chemical quencher of O2. The collected data of this
heterogeneous process allowed us to describe it using Langmuir – Hinshelwood model [2] and
to determine the kinetic parameters.
[1] M. Trytek, J. Fiedurek, A. Lipke, S. Radzki Journal of Sol-Gel Science and Technology 51, 272-286,
(2009)
[2] Z. Xiong, Xu Y, Zhu L, Zhao J. Environ Sci Technol. 15 39(2):651-7 (2005)
Page 55
Posters
Polymorphism in 1H-Pyrrolo[3,2-h]quinoline: experimental and
theoretical study
A. Gorski, S. Gawinkowski, J. Waluk
Heteroazaaromatic compounds exhibiting both hydrogen-bonding donor and hydrogenbonding acceptor properties are often investigated by a wide range of theoretical and spectroscopic methods. 1H-Pyrrolo[3,2-h]quinoline (PQ) composed of pyrrole, indole, and quinoline
moieties becomes an object of intensive study due to a new-discovered in last decade phenomenon of solvent-catalyzed excited-state tautomerization [1]. The direct intermolecular proton
transfer in similar compounds is unfavorable, because of spatial separation of donor and acceptor groups. Nevertheless, in H-bonded solute–solvent complexes in protic solvents, solventassisted excited state proton transfer becomes possible. The photophysical and spectroscopic
properties of the phototautomers differ significantly from those of a “normal” species [1], which
opens perspectives to apply mentioned group of compounds as a fluorescence probe of water
or alcohol content in medical and biological applications [2]. In spite of many studies, the vibrational assignment of PQ monomer in the ground state, as well as accurate crystal structure of
PQ dimer are still unknown.
Vibrational assignments of PQ monomer and dimer in the ground state were carried out in
our group based on IR measurements in rare gas matrices at low temperature, as well as IR
and Raman experiments in solutions at room temperature, in combination with quantum chemical density functional theory (DFT) calculations.
Two polymorph crystal forms of PQ dimer, monoclinic and triclinic were postulated. The results obtained by X-ray spectroscopy are in good agreement with theoretical calculations based
on DFT and generalized gradient approximations implemented in the CASTEP (Cambridge
Serial Total Energy Package) [3].
[1] Waluk J., Hydrogen-bonding-induced phenomena in bifunctional heteroazaaromatics, Acc. Chem. Res.
36, 832-838 (2003)
[2] Kyrychenko A. V., Waluk J., Distribution and favorable binding sites of pyrroloquinoline and its analogues
in a lipid bilayer studied by molecular dynamics simulations, Biophysical Chemistry, 136, 128-135 (2008)
[3] Segall M. D., et al., First-principles simulation: ideas, illustrations and the CASTEP code, Journal of
Physics-Condensed Matter, 14, 2717-2744 (2002)
Page 56
Posters
Spectroscopic properties of individua formed by imidazolium ionic
liquids with chloride and tetrafluoroborate anions
1
1
3
1,2
Gutowska N. , Kiszko M. , Kubicki J. , Maciejewski A.
1
Photochemistry and Spectroscopy Laboratory, Faculty of Chemistry,
2
Center for Ultrafast Laser Spectroscopy, Adam Mickiewicz University, Poznań
3
Quantum Electronics Department, Faculty of Physics, Adam Mickiewicz University, Poznań
Ionic liquids make a class of compounds consisting of organic cations such as alkylimidazolium, alkylpyridinium or tetraalkylammonium combined with a variety of organic or inorganic
anions. Recently, they have been intensively studied because of their unique physicochemical
structure-dependent properties, such as low vapour pressure, low melting point, high thermal
stability, miscibility with water or hydrophobic solvents etc. [1-3].
Imidazolium ring of ionic liquid cation can be potentially engaged in π-π interaction
with another cation’s ring. Self-association phenomena are well known for many compounds,
including imidazole and it’s methyl derivatives [4]. Unfortunately, the knowledge of aggregates
formed by ionic liquids is still insufficient. A few authors have claimed that ionic liquids can exist
as single ion pair surrounded by solvent molecules or as aggregates [5]. It is also shown
that absorption spectra of the same neat ionic liquid measured at different laboratories
are different due to presence of impurities [6]. That is why it is so difficult to determine spectroscopic properties of ionic liquids and individua which they form.
Using high-performance liquid chromatography (HPLC) combined with a spectrophotometer
with photodiode array detector (PDA) it is possible to measure absorption spectra at any time
while analysis is being performed. Concentration of the samples used makes a significant impact on results. The influence of impurities on absorption is negligibly small if ionic liquids
are used in low concentrations. Four imidazolium ionic liquids (in a broad concentration range)
were investigated under varied chromatographic conditions (column type, mobile phase composition, flow rate, injection volume). The results of this work indicate that ionic liquids can form
several individua characterised by different absorption spectra. Their presence
and concentrations depend on the concentration of ionic liquid and water content in the mobile
phase (solvent).
[1] T. Welton, P. Wasserscheid, Ionic liquids in synthesis (Wiley-VCH, 2008)
[2] J. Phys. Chem. B, Vol. 111 No. 18 (2007)
[3] N. V. Plechkova, K. R. Seddon, Chem. Soc. Rev. 37, 123 (2008)
[4] F. Peral, E. Gallego, Journal of molecular structure, 415, 187 (1997)
[5] B. Kirchner, Ionic Liquids (Springer Verlag, 2009)
[6] R. Katoh, Chem. Lett. 36, 1256 (2007) and references therein
Page 57
Posters
Analysis of the high excited B1Σ+ Rydberg state in the rare 13C17O
isotopic molecule
Hakalla R., Zachwieja M., Szajna W., Kolek P., Ostrowska-Kopeć M., Piotrowska I.,
Kępa R.
Atomic and Molecular Physics Laboratory, Institute of Physics, Rzeszów University,
[email protected]
13
17
1 +
So far unobserved in the very rare C O isotopic molecule the B Σ state was obtained on
1 + 1
the basis of Ångström system (B Σ -A Π) under high resolution as an emission spectrum using
an optic conventional spectroscopic technique. Rotationally resolved spectra of 0-2 vibrational
band is shown in Fig.1 as an example.
The light source was the hollow-cathode lamp with two anodes built in our laboratory, with
13
previously deposited small quantity of C carbon on the electrodes and filled with isotopic oxy17
gen O2. The emission from the discharge was observed with a plane grating spectrograph and
recorded by a photomultiplier tube. The spectrum of the Ångström system in the range 19300-1
13 17
21200 cm of the rare C O isotopic molecule was precisely measured and rotationally analyzed. It allowed to determine for the first time in this molecule the rotational constants for the
1 +
1
B Σ Rydberg state as well as for the lower A Π state.
1
The existence of irregularities in the strongly perturbed A Π state up to the observed Jmax
1
level was investigated in detail. Numerous rotational perturbations observed in A Π state in
13 17
C O molecule have been identified. The suspected candidates responsible for these irregu1
larities in A Π state were indicated by means of graph of the rovibronic levels. Simultaneously,
1 +
the B Σ state was turned out quite regular up to the observed Jmax level.
Fig.1 An expanded view of the 0-2 band of the B1Σ+-A1Π transition of the 13C17O. The less intensive 0-2
band of the Ångström system (B1Σ+-A1Π) system in the 13C16O molecule is treated here as the isotopic
pollution (its band head was marked with asterisk). The dotted lines indicate the tips of the relatively very
strong calibration lines.
Page 58
Posters
Spectroscopy of the B1Σ+-A1Π Ångström system in the optical
range 19200-21100 cm-1 for the 13C16O isotopic molecule
Hakalla R., Zachwieja M., Szajna W., Kolek P., Ostrowska-Kopeć M., Piotrowska I.,
Kępa R.
Atomic and Molecular Physics Laboratory, Institute of Physics, Rzeszów University,
[email protected]
-1
In the optical range of 19200-21100 cm using a conventional spectroscopic technique, the
1 + 1
13 16
emission spectrum of the Ångström system (B Σ -A Π) in C O isotopic molecule was recorded. Rotationally resolved spectra of 0-1 vibrational band is shown in Fig.1 as an example.
The light source was the hollow-cathode lamp with two anodes built in our laboratory, with pre13
viously deposited small quantity of C carbon on the electrodes and filled with isotopic oxygen.
Under high resolution the emission from the discharge was observed by using a plane grating spectrograph PGS-2 and recorded by a photomultiplier tube. The precision estimated to be
-1
0.002 - 0.005 cm . The rotational reanalysis of the bands made it possible to extend and to
improve the information for both combining states. Especially the spectroscopic and quantum1 +
mechanical constants of the B Σ Rydberg state around its v=0 level were more precise.
1
13
16
Numerous rotational perturbations observed in the A Π of the C O isotopic molecule were
1 +
confronted with the perturbation observed earlier. Simultaneously the B Σ state was turned out
quite regular up to the observed Jmax level.
Fig.1 An expanded view of the 0-1 band of the B1Σ+-A1Π transition of the 13C16O. The dotted lines indicate
the tips of the relatively very strong calibration lines.
Page 59
Posters
π-Expanded porphyrins - synthesis and photophysics
Dominik Koszelewski, Daniel T. Gryko
Institute of Organic Chemistry PAS, 01-224 Warsaw, Poland, Kasprzaka 44/52
Optical limiting is a nonlinear effect consisting of a decrease in the transmittance of the NLO
material under high-intensity illumination. Among different functions optical limiting devices can
perform, the most useful one is the protection of optical elements, sensors and human eye
against damage by exposure to a sudden high-intensity light. Dipolar or quadrupolar organic
molecules have been shown to be of particular interest since they allow combining very fast
(femtoseconds) intrinsic 2PA with somewhat slower reversed saturable absorption (RSA) [1].
The material for optical limiting applications based on RSA has to additionally possess longliving excited triplet state [2]. Compounds possessing large σ have typically short lived tripletstate. On the other hand molecules which have long-lived triplet-state, usually have small σ.
The only class of molecules which can fulfill these requirements are porphyrins [3]. Here we
would like to present the synthesis and characterization of new type of optical limiting chromophores based on new π-expanded pophyrins (Fig. 1).
Literature:
[1] Liu, Z.-Q.; Fang, Q.; Cao, D.-X.; Wang, D.; Xu, G.-B. Org. Lett. 2004, 6, 2933.
[2] Spangler, C. W. J. Mat. Chem. 1999, 9, 2013.
[3] Calvete, M.; Yang G. Y.; Hanack, M. Synthetic Metals 2004, 141, 231.
Acknowledgment:
Financial support of our work from the Foundation for Polish Science (Grant number
TEAM/2009-4/3) is gratefully acknowledged.
Page 60
Posters
Hydrogen bonds energy changes upon excitations of aminocoumarins determined from absorption solvatochromic experiment
1
1
Krystkowiak E. , Maciejewski A.
1
Faculty of Chemistry, Adam Mickiewicz University, [email protected]
Absorption spectra of three aminocoumarins (6-aminocoumarin, 6AC and 7aminocoumarins: Coumarin 120, C120, Coumarin 151, C151) were recorded in a series of nonspecifically
and
specifically
interacting solvents, especially in
polyfluorinated alcohols (HFIP,
TFE). An unusual blue-shift of a
long-wavelength in absorption
spectra of 6AC, C120 and C151
in HFIP and 6AC in TFE and
water was
observed. With
reference to theoretical results [13] it was interpreted as the
experimental proof of significant
weakening of hydrogen bond
formed by the amino group
nitrogen
atom
of
the
Fig.1 Different types of intermolecular hydrogen bonds between
aminocoumarin molecule with the
6-aminocoumarin (6AC) and protic solvents.
hydrogen
atom
of
solvent
molecule (blue bond in Fig. 1) upon photoexcitation to the electronically excited S1-LE state.
Moreover, our results obtained for 6AC in HFIP, TFE and water also indicated that upon this
transition the decrease in energy for this type of hydrogen bond was much greater than the
increase in energy of hydrogen bonds formed by the carbonyl oxygen atom and the hydrogen
atom of a protic solvent molecule (red bonds in Fig. 1).
Comparison of the solvatochromic data obtained for three aminocoumarins studied in a few
2
1-chloro-n-alkanes of different solvent polarity function, f(ε,n ), and in DMSO, permits concluding that upon the S0→S1-LE excitation of aminocoumarins the energy of hydrogen bonds
formed by hydrogen atoms of the amino group and the oxygen atom of DMSO as well as of a
protic solvent molecule (green bonds in Fig. 1) significantly increases. These results are consistent with those of the theoretical calculations [1-2].
In this study we applied simple procedure, proposed by us in Ref. [4] for accurate determination of the hydrogen bonds energy changes as a result of transition from the ground to excited
state. This procedure is based on analysis of the absorption spectra of the compound studied in
the solvents interacting with it exclusively nonspecifically (1-chloro-n-alkanes) and in those
forming only one type of hydrogen bonds with it (HFIP and DMSO respectively).
[1] Y. Liu, J. Ding, D. Shi, J. Sun, J. Photochem. Photobiol. A, 201, 203 (2009)
[2] P. Zhou, P. Song, J. Liu, K. Han, G. He, Phys. Chem. Chem. Phys., 11, 9440 (2009)
[3] G. –J. Zhao, J. –Y. Liu, L. –C. Zhou, K. –L. Han, J. Phys. Chem. B, 111, 8940 (2007)
[4] E. Krystkowiak, K. Dobek, A. Maciejewski, J. Photochem. Photobiol. A, 184, 250 (2006)
Page 61
Posters
Fluorescent properties of Rhodamine 6G in different xerogel
nanolayers and bulk materials
1
1
2
1
1
A. Lewkowicz , A. Synak , B. Grobelna , D. Jankowski , P. Bojarski
1
Institute of Experimental Physics, University of Gdańsk, [email protected]
2
Faculty of Chemistry, University of Gdańsk
The sol-gel derived materials can be exploited for the different applications, including luminescent materials, potential active media for compact tunable lasers or functional bioinspired
nanomaterials. In particular, titanium dioxide as the matrix for Rhodamine 6G molecules has
been prepared in the sol- gel process. The obtained material is highly luminescent and durable.
Spectacular increase of luminescence signal can be further obtained by spin coating Rhodamine 6G doped xerogel nanolayer over silver or gold 50 nm thick film. In this case strong directional emission of Rhodamine 6G is observed as a result of interaction between surface plasmon and molecular transition moment.
Incorporation of Rhodamine 6G at its high concentrations, results in the observation of
strongly modified steady-state and time – resolved luminescent characteristics. These changes
have been so far a subject of controversy in recent literature.
In particular, our studies performed in nanolayers and bulk materials using a variety of
steady - state and time - resolved techniques help to understand the changes observed in terms
of dye aggregation and/ or inner filter effects.
This research has been partly supported within the International PhD Project “Physics of future quantumbased information technologies” (MPD/2009- 3/4) financed by the Foundation for Polish Science.
This research has been partly supported by the European Social Fund as a part of the project "Educators
for the elite - integrated training program for PhD students, post-docs and professors as academic teachers
at University of Gdansk" within the framework of the Human Capital Operational Programme, Action 4.1.1,
Improving the quality of educational offer of tertiary education institutions.
[1]P. Bojarski, A.Matczuk, C.Bojarski, A.Kawski, B. Kukliński, C.śurkowska, H.Diehl, Chem.Phys. 210
(1996) 485.
[2] F. Del Monte and D.Levy, J.Phys.Chem.B, 130 (1999) 8080.
[3] A. Anedda, C.M. Carbonaro, R. Corpino, P.C. Ricci, S. Grand, P.C. Mustarelli, J. Non- Cryst. Solids
353 (2007) 481.
[4] Simeonika Rangełowa-Jankowska, Dawid Jankowski, Beata Grobelna, Ignacy Gryczyński, Zygmunt
Gryczyński, Robert Bogdanowicz, Piotr Bojarski, ChemPhysChem | DOI: 10.1002/cphc.201100252,
Surface-Plasmon-Coupled Emission of Rhodamine 110 in a Silica Nanolayer.
Page 62
Posters
New Fluorescent Sensors Based on 1H-Pyrazolo[3,4-b]Quinoline
Skeleton.
a
a
b
Marek Mac , Tomasz Uchacz , Andrzej Danel .
1
b)
a)
Faculty of Chemistry, Jagiellonian University, 30-060 Krakow, Ingardena 3
Department of Chemistry, University of Agriculture, 31-149 Kraków, Balicka 122, Poland
E-mail: [email protected]
Novel fluorescing dyes 1,3,4-triphenyl-6-(1,4,7,10-tetraoxa-13-aza-cyclopentadec-13-ylmethyl)1H-pyrazolo[3,4-b]quinoline
(K1),
2-[(2-hydroxyethyl)-(1,3,4-triphenyl-1H-pyrazolo[3,4b]quinolin-6-ylmethyl)-amino]ethanol
(L1) and bis-(pyridin-2-yl-methyl)-(1,3,4-triphenyl-1Hpyrazolo[3,4-b]quinolin-6-ylmethyl)-amine (P1) have been synthesized and investigated by the
means of steady state and time-resolved fluorescence techniques [1,2]. These compounds act
as sensors for the fluorescence detection of small inorganic cations (lithium, sodium, barium,
magnesium, calcium and zinc) in solvents of high polarities such as acetonitrile. The mechanism, which allows application of these compounds as sensors, is an electron transfer from the
electron-donative part of molecule to the acceptor part (fluorophore), which is retarded upon
complexation of the electron-donative part by inorganic cations. We found that crown ethercontaining compound is very sensitive to the addition of any investigated ions but amino alcohol-containing one exhibits better selectivity to the addition of two-valued cations. Two kinds of
n+
n+
the complexes (LM and L2M ) were found in the investigated systems. We found that com++
pound P1 is very sensitive to the addition of Zn cations. It shows very high selectivity to the
addition of the investigated cations [2]. Moreover, the dyes (K1 and L1) may be used as fluorescence indicators in solvents of lower polarity like tetrahydrofuran [1].
O
N
O
O
N
HO
K1
N
N
N
N
N
O
N
OH
N
N
N
N
N
P1
N
[1] M. Mac, T. Uchacz, T. Wróbel., A. Danel, E. Kulig J. Fluoresc., 20, 525, 2010.
[2] M. Mac, T. Uchacz, A. Danel, K. Danel., P. Kolek, E. Kulig , J. Fluoresc., 21, 375, 2011.
Page 63
L1
Posters
Solvent controlled photophysics of spirocyclic lactones
Majka A., Karpiuk J.
Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52,
01 – 224 Warsaw, [email protected]
Spirocyclic rhodamine lactones (LRB, LR101) provide a unique example of adiabatic photo1
chemistry – their dual fluorescence comes from a highly polar CT state ( LCT) formed after electron transfer (ET) from xanthene to phthalide subunit and an excited state of the open ring form
1
( Z) populated upon photodissociation of the C–O bond in the lactone ring [1-3]. The branching
1
1
into the deactivation pathways leading to LCT and Z states occurs in non-relaxed vibronic
levels and the lack of long term (ns) kinetic correlation proves that the emitting states are not in
1
equilibrium. The LCT deactivates to the ground state by radiative and non-radiative back ET.
1
The main deactivation channel of the Z state is the intersystem crossing to the triplet manifold
1
[4] and the deactivation rate of the Z state critically depends on solvent polarity, which is a
1
factor controlling the energy gap between the Z state and higher triplet levels of the Z form.
N(C2H5)2
(C2H5)2N
N
N
O
LRB
O
LR101
(C2H5)2N
Br
O
O
O
O
(C2H5)2N
(C2H5)2N
O
O
O
O
ODCF
VDCF
RDCF
fluorescence intensity [a.u.]
Recently, we extended our research to include LRB analogs with asymmetrically substituted
(ODCF, VDCF) or modified (RDCF) electron-donating xanthene moiety. All these molecules
1
display dual fluorescence from LCT
wavelenght (nm)
1
800 700
600
500
400
and Z states, though the latter
emission is observed in a much
14
298K 14
VDCF in PrOH
narrower range of solvent polarity
243K 12
12
λ =310 nm
223K
than for LRB (Fig. 1) and requires
10
203K 10
specific combinations of solvent
163K
8
8
polarity and dielectric relaxation
143K
time. These findings prove that
6
123K 6
adiabatic photodissociation is a
103K
4
4
93K
general feature of spirocyclic donor2
2
acceptor systems and that the intersystem crossing plays a major role
0
0
12000
16000
20000
24000
28000
in photophysics of rhodamines,
-1
especially when the Z form is
wavenumber [cm ]
populated in absence of hydrogen
Fig. 1 Luminescence of VDCF in n-propanol as a
bonding with the solvent. A detailed
function of temperature.
study of VDCF photophysics as a
function of solvent polarity and proticity will be presented and compared with those of ODCF,
RDCF and LRB.
ext
[1] U. K. A. Klein, W. F. Hafner, Chem. Phys. Lett. 43, 141 (1976)
[2] T. M. Grigoryeva, V. L. Ivanov, N. Nizamov, M. G. Kuzmin Dokl. Akad. Nauk 232, 1108 (1977)
[3] J. Karpiuk, Z. R. Grabowski, F. C. De Schryver J. Phys. Chem. 98, 3247 (1994)
[4] J. Karpiuk, J. Luminesc. 60-61, 474 (1994)
Page 64
Posters
Analysis of the absorption and emission spectra of Photofrin
Pszona M., Waluk J.
Photofrin, known as porfimer sodium, is a porphyrin derivative used in the photodynamic
therapy (PDT) of tumors. Analysis of this photosensitizing agent is a challenging task as Photofrin is a mixture of oligomers formed by
porphyrin units linked through ether and
ester bonds [1].
Analyses using different mass spectral
ionization techniques provided distribution
of the oligomers obtained with desalted
Photofrin, which consists of two to eight
porphyrin units with average 2.5-2.9 [2].
We obtained excitation/fluorescence
map for methanol solution of Photofrin II
and used principal component analysis
(PCA [3]) as a way to obtain the number
of components in the mixture, their excitation and emission spectra.
The obtained results show that the
first principal component is significantly
larger than the others. Moreover, it provides 99% of total variance. This could
mean that there is only one dominant
oligomer in Photofrin or that the emission
Fig.1 Excitation/fluorescence map.
and excitation spectra of all compounds
are very similar and make this method not applicable in estimating the distribution of oligomers.
The apparent homogeneity of Photofrin emission was confirmed by the finding that the investigation of fluorescent lifetimes showed only one decay component.
[1] Photofrin (porfimer sodium), Highlights of prescribing information,
http://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=5c4841b4-fbc0-4163-8ee1-cb28629cbfbf
[2] M. M. Siegel, K. Tabei, R. Tsao, M. J. Pastel, R. K. Pandey, S. Berkenkamp, F.Hillenkamp, M. S. de
Vries, J. Mass. Spectrom. 34, 661-669 (1999)
[3] R. Wehrens, Chemometrics with R: Multivariate Data Analysis in the Natural Sciences and Life
Sciences (Springer-Verlag, Berlin, 2011)
Page 65
Posters
8-Azapurines: fluorescent, isosteric alternatives to natural purine
bases
Wierzchowski J., Medza G.
Department of Physics & Biophysics, Faculty of Food Sci., University of Warmia & Mazury in
Olsztyn, [email protected]
fluorescence [a.u.]
Natural purines and pyrimidines, or nucleic acid bases, as well as the corresponding nucleo-4
sides/nucleotides, are characterized by very low fluorescence yields (~10 ) and low picosecond
excited state lifetimes in neutral aqueous media [1]. Although many fluorescent base and nucleoside/nucleotide analogues are known [2], their application to biological research is in many
cases limited because of bulkiness of the applied modifications, thus interfering with biological
systems studied. The present paper summarizes room-temperature fluorescence properties of
8-azapurines, which are isosteric, and biologically active analogues of the natural purines: adenine, guanine, and so on. Special attention will be devoted to the photon-induced tautomerism
in the foregoing class of compounds, recently reviewed by us [3].
Fluorescence properties of 8-azaadenine, 8-azahypoxanthine and 8-azaguanine, and the
corresponding nucleosides, were described several years ago [4]. These compounds were
successfully applied in polynucleotide
250
and ribozyme research [5,6]. Recently,
we have found that 8-azaxanthine [7], 8200
azaisoguanine [8], and 8-aza-2,6dimethylaminopurine
(unpublished)
150
exhibit moderate to intense fluorescence
in aqueous media.
Some of the
foregoing compounds undergo excited100
state intermolecular proton transfer
[3,7,8], which makes them particularly
50
interesting candidates for the biophysical
applications.
0
34000
30000
26000
22000
18000
This
work
will
show
some
wavenumber [1/cm]
unpublished data on phototautomeric
Fig.1 Effect of TEA/Acetic acid, 10-310 mM, on the fluobehaviour of 8-azaisoguanine, 8-azarescence of 8-aza-2,6-diaminopurine in isopropanol.
2,6-diaminopurine, and some of their Nmethyl
derivatives.
In
particular,
deuterium isotope, solvent, and buffer concentration effects on the room-temperature fluorescence were studied, with results exemplified in Fig. 1.
[1] M. Daniels, in: Photochemisty and photobiology of nucleic acids, vol. 1, Chapt. 2, Academic, 1976.
[2] R.W. Sinkeldam, N.J. Greco, Y. Tor, Chemical Reviews 110, 2579 (2010)
[3] J. Wierzchowski, Current Topics in Biophysics online (Poznan) 33, 9 (2010)
[4] J. Wierzchowski, B. Wielgus-Kutrowska, D. Shugar, Biochim. Biophys. Acta 1290, 9 (1996)
[5] L. Liu, J.W. Cottrell, L.G. Scott, M.J. Fedor, Nature Chemical Biology 5, 351 (2010)
[6] D. Jiang , F. Seela, J. Amer. Chem. Soc. 132, 4016 (2010)
[7] J. Wierzchowski, J., Sepioł, D. Sulikowski, B. Kierdaszuk, D. Shugar, J. Photochem. Photobiol. A:
179, 276 (2006).
[8] J. Wierzchowski, G. Mędza, D. Shugar, Clollections Symp. Series 10, 476 (2008)
Page 66
Notes
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Notes
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Notes
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Notes
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Molecules and Light 2011

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