Dinitriles bearing AIE-active moieties: synthesis, E/Z isomerization, and fluorescence properties.

Dinitriles bearing aggregation-induced emission (AIE)-active moieties [tetraphenylethylene (TPE) or diphenylphenanthrene (DPP)] were prepared. Compounds 4 (TPE-linked) and 8 (DPP-linked) showed considerably redshifted emission resulting from their large Stokes shifts and also strong fluorescence in the aggregated and solid states. Pure E and Z stereoisomers of both dinitriles were easily separated, and their isomerization equilibria and fluorescence properties were investigated. In addition to their pronounced AIEE behavior, 4 and 8 also showed various reversible chromic responses to external stimuli, namely, solvato-, piezo-, vapo-, and thermochromism, which make them potential candidates for smart materials.