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The Influence of Electron-Withdrawing Groups at the 2- and 2′-Positions of Dibenzothienylethenes on Molecular Switching
Received: 13 February 2017
Accepted after revision: 28 March 2017
02 May 2017 (eFirst)
Three dibenzothienylethenes that carry a methyl, a trifluoromethyl, or a fluoro substituent in the 2- and 2′-position were synthesised in short multistep syntheses, respectively. The trifluoromethyl and fluoromethyl substituents significantly improve the absorption properties of the corresponding open and closed isomers (both in the UV-A and in the visible range). The increasing electron deficiency (i) enlarges the portion of the closed and coloured diarylethene isomer in the corresponding photostationary states and slows down the closing and opening isomerisation, (ii) the switching reactions, both closing and opening, are slowed down, and (iii) the switching quantum yields are lowered.