title: β-Phenyl quenching of 9-phenylphenalenones: a novel photocyclisation reaction with biological implications.
abstract: The singlet and triplet excited states of 9-phenylphenalenones undergo β-phenyl quenching (BPQ) via addition of the carbonyl oxygen to the ortho position of the phenyl substituent. This reaction leads to the formation of naphthoxanthenes , which, in the absence of quenchers, undergo a very rapid electrocyclic ring opening reaction reverting to within a few microseconds. Naphthoxanthene contains a remarkably weak C-H bond, which enables efficient hydrogen transfer reactions to suitable acceptors, giving rise to the production of the naphthoxanthenyl radical or the naphthoxanthenium cation, depending on the solvent polarity. The study uncovers a number of new aspects of BPQ and suggests an excited state-mediated metabolic pathway in the biosynthesis of plant fluorones.
authors: WestCHEM, School of Chemistry, University of Glasgow, Joseph-Black-Building, University Avenue, Glasgow G12 8QQ, UK. goebu@chem.gla.ac.uk.
authors: Götz
authors: G
authors: Bucher
authors: Roger
authors: R
authors: Bresolí-Obach
authors: Carme
authors: C
authors: Brosa
authors: Cristina
authors: C
authors: Flors
authors: Javier G
authors: JG
authors: Luis
authors: Teresa A
authors: TA
authors: Grillo
authors: Santi
authors: S
authors: Nonell
mesh_terms: D002244:Carbon / Q000737:chemistry; D003500:Cyclization; D006859:Hydrogen / Q000737:chemistry; D007659:Ketones / Q000737:chemistry; D008027:Light; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D010100:Oxygen / Q000378:metabolism; D043803:Phenalenes / Q000737:chemistry*; D011789:Quantum Theory; D013056:Spectrophotometry, Ultraviolet
chemical_list: D007659:Ketones; D043803:Phenalenes; D002244:Carbon; D006859:Hydrogen; D010100:Oxygen