title: Trans-cis isomerization of vinylketones through triplet 1,2-biradicals.
abstract: The irradiation of trans-vinylketones 1a-c yields the corresponding cis isomers 2a-c. Laser flash photolysis of 1a and 1b with 308 and 355 nm lasers results in their triplet ketones (T1K of 1), which rearrange to form triplet 1,2-biradicals 3a and 3b, respectively, whereas irradiation with a 266 nm laser produces their cis-isomers through singlet reactivity. Time-resolved IR spectroscopy of 1a with 266 nm irradiation confirmed that 2a is formed within the laser pulse. In comparison, laser flash photolysis of 1c with a 308 nm laser showed only the formation of 2c through singlet reactivity. At cryogenic temperatures, the irradiation of 1 also resulted in 2. DFT calculations were used to aid in the characterization of the excited states and biradicals involved in the cis-trans isomerization and to support the mechanism for the cis-trans isomerization on the triplet surface.
authors.affiliation: Department of Chemistry, University of Cincinnati , Cincinnati, Ohio 45221, United States.
authors.forename: R A A Upul
authors.initials: RA
authors.lastname: Ranaweera
authors.forename: Tianeka
authors.initials: T
authors.lastname: Scott
authors.forename: Qian
authors.initials: Q
authors.lastname: Li
authors.forename: Sridhar
authors.initials: S
authors.lastname: Rajam
authors.forename: Alexander
authors.initials: A
authors.lastname: Duncan
authors.forename: Rui
authors.initials: R
authors.lastname: Li
authors.forename: Anthony
authors.initials: A
authors.lastname: Evans
authors.forename: Cornelia
authors.initials: C
authors.lastname: Bohne
authors.forename: John P
authors.initials: JP
authors.lastname: Toscano
authors.forename: Bruce S
authors.initials: BS
authors.lastname: Ault
authors.forename: Anna D
authors.initials: AD
authors.lastname: Gudmundsdottir