Preparation, structure, and redox behavior of bis(diarylmethylene)dihydrothiophene and its π-extended analogues.

The preparation, X-ray structure, and optoelectronic properties of bis(diarylmethylene)dihydrothiophene 1 and its π-extended analogues 2 are described. The development of a simple, short-step synthetic route allowed us to prepare derivatives with different aryl units. X-ray crystallographic analysis of 1b and 2b revealed their quinoidal structures, which exhibit strong electronic absorption in the visible region. Cyclic voltammetry measurements revealed their strong electron-donating properties. 1b showed two-step electrochromic behavior between the corresponding radical cation and dication.