Photochromic Dithienylethene-Containing Triarylborane Derivatives: Facile Approach to Modulate Photochromic Properties with Multi-addressable Functions

A series of dithienylethene-containing triarylboranes has been designed, synthesized, and characterized. The electrochemistry, photophysics, and photochromic behavior have also been studied. The photophysical and photochromic properties could be facilely tuned in this system by varying the thiophene spacers (thiophene, thienothiophene, and bithiophene) between the dithienylethene and the dimesitylboron (BMes(2)) or the position of the BMes(2) substitution in the thiophene spacers. The absorption of closed form has been found to be more sensitive towards the structural modification upon incorporation of the BMes(2) unit. Moreover, multi-addressable photochromic reactivity is obtained upon addition of Lewis base (F-), which is due to the formation of boron-Lewis base adduct. The dependence of the photophysical and photochromic properties on the thiophene spacers and the position of the BMes(2) substitution has been further supported by computational studies.