Syntheses, structures, and photoisomerization of (E)- and (Z)-2-tert-butyl-9-(2,2,2-triphenylethylidene)fluorene

ORGN 231

Thomas W. Bell, Rolando Procupez, Daniel J. Phillips, Vincent J. Catalano, James W. Barr, and Joseph I. Cline. Department of Chemistry/216, University of Nevada, Reno, NV 89557-0020

Light mediated interconversion of cis and trans stilbene and other 1,2-diarylethenes has been well studied, but photoisomerization of 1,1-diarylethenes has scarcely been investigated. In order to evaluate the sterically geared alkene 9-(2,2,2-triphenylethylidene)fluorene as a chromophore for use in light-driven molecular motors, we synthesized the 2-tert-butyl derivative in five steps from fluorene. Separation of the E and Z stereoisomers by chromatography and crystallization gave pure samples of each. Their structures have been determined by X-ray crystallography, and the quantum yields for photoisomerization have been measured at various wavelengths.

Physical Organic Chemistry: Calculations, Mechanisms, Photochemistry, and High-Energy Species 8:00 AM-12:00 PM, Tuesday, March 30, 2004 Anaheim Convention Center -- 303A, Oral Division of Organic Chemistry The 227th ACS National Meeting, Anaheim, CA, March 28-April 1, 2004