Synthesis and characterization of nonsymmetric cyclopentene-based dithienylethenes.

Nonsymmetric cyclopentene-based dithienylethenes, containing both thienyl and benzothienyl units, have been synthesized for the first time, employing intramolecular McMurry reaction as a key transformation to target compounds 10 and 16. Photochromic properties of these compounds were examined in toluene and acetonitrile solutions, PMMA layers, solid films, and crystal phase. To explain an unprecedented single-crystalline photochromism phenomena of 10, X-ray crystallographic analysis was performed, revealing a significant influence of strong S···S interatomic interactions on the intramolecular distance between two photochemical reaction centers in the molecule.