Substituent position effect on photochromic properties of aldehyde-functionalized dithienylethenes.

Three symmetrical dithienylethenes bearing two electron-withdrawing aldehyde groups have been synthesized. And their structures were confirmed by 1H NMR, 13C NMR and HRMS (ESI). Investigation on photochromic properties indicated that they had good photochromic behavior with excellent fatigue resistance upon irradiation with UV or visible light. And it was found that the aldehyde substituent position had a significant effect on their photochromic properties. The DFT calculations further validated those experimental results for their photochromic behavior. Furthermore, they may be used as versatile building blocks to construct novel photochromic materials. [ABSTRACT FROM AUTHOR]