Carbon dioxide and water as a key for unlocking photochromism of diarylethene derivative

A photochromic diarylethene derivative with 4-(ethylideneamino) phenol group (1a) is prepared, and 1a exhibits ring-opening and ring-closing photoisomerization with UV/vis light irradiation in solution. Addition of base to both solution of ring-open isomer 1a and ring-closed isomer 1b produces deprotonated compounds 2a and 2b, respectively, and both 2a and 2b are photo-inactive and no photochemical reaction is detected in solution in the absence of carbon dioxide and water. Both 2a and 2b are, however, converted back to 1a and 1b when the solution contains carbon dioxide and water, and photochromic reaction is recovered. This may provide a means to generate a gate for non-destructive readout. Meanwhile, the conversion between species is accompanied color change in a wide range by combination of photo-trigger and chemical trigger. The system endowed with multi-responsive functionality for multi-color change is beneficial for applications such as display and camouflage.