Phys Chem Chem Phys 2011 Apr 15;13(15):6981-91. Epub 2011 Mar 15.
Laboratory of Applied Photochemistry, Faculty of Chemistry, A. Mickiewicz University, Grunwaldzka 6, 60-780 Poznań, Poland.
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Photochem Photobiol Sci 2011 Oct 1;10(10):1670-9. Epub 2011 Aug 1.
Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, 60-780, Poznań, Poland.
Absorption, steady-state and timed-resolved fluorescence spectra of nine N-p-bromobenzyl substituted (E)-4'-hydroxy-4-stilbazolium bromides and N-p-bromo- (or nitro-) benzyl substituted (E)-4'-hydroxy-3'methoxy-4-stilbazolium bromides, belonging to the hemicyanine class of compounds, were studied in dry and water-containing polar solvents and in water. All of the studied compounds displayed negative solvatochromism. In solvents with small amounts of water the solutions of each of the compounds change color to red, blue-green or blue, while in extra dry solvents they are all yellow. Read More
Photochem Photobiol Sci 2012 Sep 29;11(9):1454-64. Epub 2012 Jun 29.
Faculty of Chemistry, A. Mickiewicz University, Grunwaldzka 6, 60-780 Poznań, Poland.
The protonation/deprotonation equilibrium was investigated for N-p-chlorobenzyl-substituted (E)-4'-hydroxy stilbazolium halide, namely (E)-1-(4-chlorobenzyl)-4-(4-hydroxystyryl)pyridinium chloride (EPC). Absorption, emission and synchronous scanning spectra were used to explain the observed phenomena. The excited state lifetimes of the protonated and deprotonated forms of EPC were measured and discussed. Read More
J Phys Chem A 2006 Sep;110(38):11025-33
Faculty of Chemistry, A. Mickiewicz University, Grunwaldzka 6, 60-780 Poznan, Poland.
The spectral and photophysical behavior of four fluorescent 9-oxo-imidazo[1,2-a]purine derivatives containing pyridyl, pyridylphenyl, phenyl, and biphenylyl substituents at the C(6) position of the tricyclic skeleton is described. The studies were performed in several aprotic and protic organic solvents using absorption spectroscopy as well as steady-state and time-resolved fluorescence spectroscopy. The results are also presented of TDDFT calculations on singlet-singlet excitation energies and oscillator strengths for two models of 9-oxo-imidazo[1,2-a]purine, with phenyl or pyridyl substituents, both in the gas phase and in methanol solution. Read More
Photochem Photobiol Sci 2005 Apr 18;4(4):367-75. Epub 2005 Feb 18.
Department of Chemistry, Gunma University, Kiryu, Gunma, 376-8515, Japan.
Effects of intra- and intermolecular hydrogen-bonds on the photophysical properties of 2'-aminoacetophenone derivatives (X-C6H4-COCH3) having a substituted amino group (X) with different hydrogen-bonding ability to the carbonyl oxygen (X: NH2(AAP), NHCH3(MAAP), N(CH3)2(DMAAP), NHCOCH3(AAAP), NHCOCF3(TFAAP)) are investigated by means of steady-state and time-resolved fluorescence spectroscopy and time-resolved thermal lensing. Based on the photophysical parameters obtained in aprotic solvents with different polarity and protic solvents with different hydrogen-bonding ability, the characteristic photophysical behavior of the 2'-aminoacetophenone derivatives is discussed in terms of hydrogen-bonding and n,pi*-pi,pi* vibronic coupling. The dominant deactivation process of AAP and MAAP in nonpolar aprotic solvents is the extremely fast internal conversion (k(ic)= 1. Read More