Photophysical properties of lumichromes in water

The photophysics of lumichrome, 1-methyllumichrome, and lumiflavin in water solutions have been investigated. Fluorescence lifetimes of 2.7 and 2.2 ns were observed for lumichrome and 1-methyllumichrome, respectively. the cor responding triplet state lifetimes of 17 and 18 mus have been obtained from the transient absorption spectra. Evidence for long lived species with abs orption maxima near 450 nm and lifetimes of ca. 400 mus has been found in t he transient absorption spectra of both lumichromes. Quantum yields for the sensitised production of singlet oxygen, phi (Delta), are 0.36 and 0.41 fo r lumichrome and 1-methyllumichrome, respectively, in D2O. (C) 2001 Elsevie r Science BY All rights reserved.