Carbazole N-substituent effect upon DTMA: stabilizing and photochromic modulating

Dithienylmaleimide derivatives 7-27 were synthesized by introducing N-substituted carbazole for photo-stabilizing purpose, and the structures were fully confirmed. The photochromism and photo-stability were recorded via UV-vis spectra. Only ortho compounds 8-17 with N-substituents on carbazole moiety showed escalated photochromic change, while compound 7 and the para counterparts 18-27 showed no appreciable photochromism. Additionally, compounds 8-18 exhibited good photo-stability except 17 under 254 nm irradiation. The unstability of 17 may probably due to overrunning hindrance. These photochromic patterns indicated that hindrance and electronic effect mutually paid a decisive influence on the photochromism and photo-stability, which potentially exploited a new way to construct novel photochromic materials with regulable and conceivable performance.