title: Photochemical studies of A2-E.
abstract: 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 approximately 30 micros, it is efficiently quenched by molecular oxygen with a second-order quenching rate constant of approximately 1 x 10(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.
authors.affiliation: School of Chemistry and Physics, Lennard-Jones Laboratories, Keele University, Staffordshire ST5 5BG, UK. a.cantrell@chem.keele.ac.uk
authors.forename: A
authors.initials: A
authors.lastname: Cantrell
authors.forename: D J
authors.initials: DJ
authors.lastname: McGarvey
authors.forename: J
authors.initials: J
authors.lastname: Roberts
authors.forename: T
authors.initials: T
authors.lastname: Sarna
authors.forename: T G
authors.initials: TG
authors.lastname: Truscott
mesh_terms: D000873:Anthracenes / Q000737:chemistry; D001554:Benzene / Q000737:chemistry; D000432:Methanol / Q000737:chemistry; D015394:Molecular Structure; D009281:Naphthalenes / Q000737:chemistry; D010777:Photochemistry; D010782:Photolysis; D012176:Retinoids / Q000737:chemistry*
chemical_list: C112040:A2-E (N-retinylidene-N-retinylethanolamine); D000873:Anthracenes; D009281:Naphthalenes; D012176:Retinoids; C016614:1-nitronaphthalene; C034020:anthracene; D001554:Benzene; D000432:Methanol