Photophysics of alloxazines on cellulose.

Authors:
Marek Sikorski
Marek Sikorski
A. Mickiewicz University
Poland
Ewa Sikorska
Ewa Sikorska
Poznań University of Economics
Poland
Jose L Bourdelande
Jose L Bourdelande
A. Mickiewicz University
Poland
Aleksander Siemiarczuk
Aleksander Siemiarczuk
University of Guelph
Canada

Photochem Photobiol Sci 2002 Sep;1(9):715-20

Faculty of Chemistry, A. Mickiewicz University, Grunwaldzka 6, 60-780 Poznań, Poland.

We report the UV-Vis absorption, fluorescence and transient absorption spectra of selected methylalloxazines adsorbed on cellulose from a polar solvent. The ground-state properties of these probe molecules in the cellulose matrix are similar to those in polar protic solvents. Fluorescence decay data allowed identification of three emitting species for every molecule studied, excluding 1-methyllumichrome which lacks the capacity to rearrange into an isoalloxazinic form. The short-lived emission component was attributed to the neutral form of the molecule, and the two longer-lived components were assigned to the two distinct deprotonated monoanionic forms resulting from dissociation at the respective N(3) and N(1) nitrogen atoms. The two monoanions coexist due to their very similar pKa, values. Transient absorption experiments detected two species created by the laser pulse in these systems. The short-lived species was identified as the triplet excited state, and the long-lived species as the semireduced radical, formed by hydrogen atom or proton transfer from the glycosidic unit to the alloxazine carbonyl group.
September 2002
7 Reads
2.27 Impact Factor

Publication Analysis

Top Keywords

transient absorption
8
deprotonated monoanionic
4
monoanionic forms
4
distinct deprotonated
4
assigned distinct
4
longer-lived components
4
components assigned
4
forms dissociation
4
dissociation respective
4
monoanions coexist
4
coexist pka
4
atoms monoanions
4
nitrogen atoms
4
respective nitrogen
4
molecule longer-lived
4
form molecule
4
capacity rearrange
4
rearrange isoalloxazinic
4
lacks capacity
4
1-methyllumichrome lacks
4

Similar Publications

Acid-base equilibriums of lumichrome and its 1-methyl, 3-methyl, and 1,3-dimethyl derivatives.

J Phys Chem A 2012 Jul 10;116(28):7474-90. Epub 2012 Jul 10.

Faculty of Chemistry, A. Mickiewicz University, Grunwaldzka 6, 60-780 Poznań, Poland.

Lumichrome photophysical properties at different pH were characterized by UV-vis spectroscopy and steady-state and time-resolved fluorescence techniques, in four forms of protonation/deprotonation: neutral form, two monoanions, and dianion. The excited-state lifetimes of these forms of lumichrome were measured and discussed. The results were compared to those obtained for similar forms of alloxazine and/or isoalloxazine, and also to those of 1-methyl- and 3-methyllumichrome and 1,3-dimethyllumichrome. Read More

View Article
July 2012

Effect of solvent on the excited-state photophysical properties of curcumin.

Photochem Photobiol 2000 Nov;72(5):625-31

Radiation Chemistry & Chemical Dynamics Division, Bhabha Atomic Research Center, Trombay, Mumbai, India.

Photophysical properties of curcumin, 1,7-bis-(4-hydroxy-3-methoxy phenyl)-1,6-heptadiene-2,5-dione, a pigment found in the rhizomes of Curcuma longa (turmeric) have been studied in different kinds of organic solvent and also in Triton X-100 aqueous micellar media using time-resolved fluorescence and transient absorption techniques having pico and nanosecond time resolution, in addition to steady-state absorption and fluorescence spectroscopic techniques. Steady-state absorption and fluorescence characteristics of curcumin have been found to be sensitive to the solvent characteristics. Large change (delta mu = 6. Read More

View Article
November 2000

Triplet- vs. singlet-state imposed photochemistry. The role of substituent effects on the photo-Fries and photodissociation reaction of triphenylmethyl silanes.

Photochem Photobiol Sci 2005 Jun 11;4(6):469-80. Epub 2005 May 11.

Department of Chemistry, University of Ioannina, 451 10 Ioannina, Greece.

The photochemistry of three structurally very similar triphenylmethylsilanes 1, 2, 3 [p-X-C(6)H(4)-CPh(2)-SiMe(3): X = PhCO, 1; H, ; Ph(OCH(2)CH(2)O)C, 3] is described by means of 248 and 308 nm nanosecond laser flash photolysis (ns-LFP), femtosecond LFP, EPR spectroscopy, emission spectroscopy (fluorescence, phosphorescence), ns-pulse radiolysis (ns-PR), photoproduct analysis studies in MeCN, and X-ray crystallographic analysis of the two key-compounds 1 and 2. The photochemical behavior of 1, 2 and 3 is discussed and compared with that of a fourth one, 4, bearing on the p-position an amino group (X = Me(2)N) and whose detailed photochemistry we reported earlier (J. Org. Read More

View Article
June 2005

Photophysics and photochemistry of nalidixic acid.

Photochem Photobiol 2006 Jan-Feb;82(1):254-61

Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile.

The photophysics and photochemistry of nalidixic acid (NA) were studied as function of pH and solvent properties. The ground state of NA exhibits different protonated forms in the range of pH 1.8-10. Read More

View Article
June 2006