Base-gated photochromism of C3-Symmetric AIEgens through multicyano-sensitized benzene rings

It is extremely challenging but desirable to combine photoresponsive functions such as photochromism into aggregation-induced emission (AIE) molecules through a simple and low-cost strategy. Herein a series of C3-symmetric molecules with aggregation-induced emission and base-gated photochromism have been synthesized. The new compounds generally show excellent photophysical characteristics in solid-state with bright fluorescence and red-shifted emission by changing halogens and extending conjugation respectively. Compared with the more usual thiophene/furan-containing derivatives which show one-step discoloration, these C3-symmetric molecules which are constructed by low-cost benzene rings can only exhibit obvious photochromic behaviours in basic solutions, showing the great potential of detecting toxic organic bases and the base-gated function. Furthermore, we demonstrate this charming base-gated photochromism could be attributed to multicyano-sensitized benzene rings of these AIE luminogens through changing the number of cyano-vinylene bridges step-by-step.