title: Syntheses of dihydropyrene-cyclophanediene negative photochromes containing internal alkenyl and alkynyl groups and comparison of their photochemical and thermochemical properties.
abstract: Synthesis of a variety of 8,16-disubstituted-anti-[2.2]metacyclophanedienes (CPD) with alkenyl and alkynyl internal (8,16) groups is described together with their analogous dihydropyrenes (DHP). Eyring and Arrhenius parameters were determined for the thermal closing reaction, CPD to DHP, and half-lives at 20 °C were found to range from 11 days (X = CHO) to 36 years (X = CN), with alkenyl functions being from 56 days to 10 years. The visible light opening reaction, DHP to CPD, showed relative rates of 1 (X = CN) to 240 (X = CH═CMe2).
authors.affiliation: Department of Chemistry, University of Victoria , P.O. Box 3065, Victoria, BC, Canada V8W 3V6.
authors.forename: Khurshid
authors.initials: K
authors.lastname: Ayub
authors.forename: Reginald H
authors.initials: RH
authors.lastname: Mitchell