Photochemical studies of A2-E

Lipofuscin is thought to be involved in age-related macular degeneration as is one of its proposed components, an amphiphillic pyridinium-based bis-retinoid with a quaternary nitrogen atom. known as A2-E. We report the triplet state spectra obtained from photosensitisation using anthracene and 1-nitronaphthalene in benzene and methanol. The triplet state of A2-E has lambda (max) at 550 nm and a lifetime of similar to 30 mus, it is efficiently quenched by molecular oxygen with a second-order quenching rate constant of similar to 1x10(9) dm(3) mol(-1) s(-1). There is no significant triplet state formation from direct laser excitation of A2-E and hence its quantum yield of triplet state formation must be <0.01. (C) 2001 Elsevier Science B.Y. All rights reserved.