title: Photochemical dimerization of acephenanthrylene and the heavy atom effect
abstract: The solution-phase photodimerization of acephenanthrylene (1) in cyclohexane, chloroform, dibromomethane, and ethyl iodide with visible light (lambda = 419 nm) occurs to form cis (2) and trans (3) photodimers in ratios that vary with the solvent and with the presence or absence of oxygen. The photodimerization exhibits a significant heavy atom effect and also is sensitive to selective quenching by dissolved oxygen, in which only cis stereoisomers are produced. Irradiation of the dimers (lambda = 254 nm) shows that the trans dimers cleave more rapidly than the cis dimers. This is attributed to stabilization of the excited state in the cis dimers.
authors.affiliation: Department of Chemistry, Trinity University, San Antonio, Texas 78212-7200, USA.
authors.initials: BF
authors.lastname: Plummer
authors.initials: MJ
authors.lastname: Moore
authors.initials: J
authors.lastname: Wright