Issue 9, 2002

Photophysics of alloxazines on cellulose

Abstract

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.

Graphical abstract: Photophysics of alloxazines on cellulose

Article information

Article type
Paper
Submitted
06 Jun 2002
Accepted
03 Jul 2002
First published
26 Jul 2002

Photochem. Photobiol. Sci., 2002,1, 715-720

Photophysics of alloxazines on cellulose

M. Sikorski, E. Sikorska, I. V. Khmelinskii, R. Gonzalez-Moreno, J. L. Bourdelande and A. Siemiarczuk, Photochem. Photobiol. Sci., 2002, 1, 715 DOI: 10.1039/B205452C

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