title: Synthesis and Photoisomerization of Substituted Dibenzofulvene Molecular Rotors.
abstract: The synthesis, spectral and structural characterization, and photoisomerization of a family of 2-substituted dibenzofulvene molecular actuators based on (2,2,2-triphenylethylidene)fluorene (TEF) are reported. The 2-substituted species investigated are nitro (NTEF), cyano (CTEF), and iodo (ITEF). X-ray structures of these three compounds and three intermediates were determined to assign alkene configuration and investigate the effects of the 2-substituents on steric gearing. The addition-elimination reaction of Z-9 with trityl anion to form Z-10 proceeded with complete retention of configuration. Rates of photoisomerization were measured at irradiation wavelengths between 266-355 nm in acetonitrile/dioxane solutions at room temperature. Photoisomerization quantum yields (φ) were calculated by means of a mathematical model that accounts for a certain degree of photodecomposition in the cases of CTEF and ITEF. Quantum yields vary significantly with substituent, having maximum values of φ=0.26 for NTEF, 0.39 for CTEF, and 0.50 for ITEF. NTEF is photochemically robust and has a large quantum yield for photoisomerization in the near-UV, making it a particularly promising drive rotor moiety for light-powered molecular devices.
authors.affiliation: Department of Chemistry and Program in Chemical Physics, University of Nevada, Reno, NV, 89557-0216, USA.
authors.forename: Stephanie C
authors.initials: SC
authors.lastname: Everhart
authors.affiliation: Department of Chemistry and Program in Chemical Physics, University of Nevada, Reno, NV, 89557-0216, USA.
authors.forename: Udaya K
authors.initials: UK
authors.lastname: Jayasundara
authors.affiliation: Department of Chemistry and Program in Chemical Physics, University of Nevada, Reno, NV, 89557-0216, USA.
authors.forename: HyunJong
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Chemistry and Program in Chemical Physics, University of Nevada, Reno, NV, 89557-0216, USA.|Coordinador Sección Química General, Escuela de Química, Universidad de Costa Rica, P.O. Box 11501-2060, Costa Rica.
authors.forename: Rolando
authors.initials: R
authors.lastname: Procúpez-Schtirbu
authors.affiliation: Department of Chemistry and Program in Chemical Physics, University of Nevada, Reno, NV, 89557-0216, USA.
authors.forename: Wayne A
authors.initials: WA
authors.lastname: Stanbery
authors.affiliation: Department of Chemistry and Program in Chemical Physics, University of Nevada, Reno, NV, 89557-0216, USA.
authors.forename: Clay H
authors.initials: CH
authors.lastname: Mishler
authors.affiliation: Department of Chemistry and Program in Chemical Physics, University of Nevada, Reno, NV, 89557-0216, USA.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Frost
authors.affiliation: Department of Chemistry and Program in Chemical Physics, University of Nevada, Reno, NV, 89557-0216, USA.
authors.forename: Joseph I
authors.initials: JI
authors.lastname: Cline
authors.affiliation: Department of Chemistry and Program in Chemical Physics, University of Nevada, Reno, NV, 89557-0216, USA. twb@unr.edu.
authors.forename: Thomas W
authors.identifier: http://orcid.org/0000-0003-4986-9180
authors.initials: TW
authors.lastname: Bell
keywords: alkenes; aromatic compounds; isomerization; molecular switches; photophysics