Double-Layered 1,4-Distyrylbenzene Chromophores - Synthesis, UV and Fluorescence Spectra

Abstract

The reaction of [2.2]paracyclophane (1) with liquid bromine affords a 1:1 mixture of only two isomeric products, the pseudo-para 2 and pseudo-ortho tetrabromide 3. The structure of the pseudo-para isomer 2 has been determined by X-ray structure analysis. Fourfold palladium-catalyzed coupling with styrenes and with methyl acrylate converts 2 and 3 into double-layered derivatives as e.g. 6a, 7a, and 7b, respectively. The molecular structure of 7a has been established by X-ray structure analysis. The UV and fluorescence spectra of a variety of substituted products are reported and compared with those of the parent chromophors 2,5-dimethyl-1,4-distyrylbenzene (16) and 2,5-diethyl-1,4-bis(phenylethynyl)benzene (17), respectively.