Impact of a dithienyl unit on photostability of N,C-chelating boron compounds.

A dithienyl unit in a N,C-chelate monoboryl compound has been found to completely stabilize a N,C-chelate boryl chromophore toward photoisomerization. N,C-chelate diboryl compounds that contain a dithienyl unit display a similar high stability toward photoisomerization. This greatly enhanced photostability is attributed to the π → π* transition and luminescence involving the dithienyl unit that competes effectively with photoisomerization of the boryl chromophore.