Photochromism of a Radical Diffusion-Inhibited Hexaarylbiimidazole Derivative with Intense Coloration and Fast Decoloration Performance

We report the synthesis and the photochromic behavior of a newly designed, photochromic, radical diffusion-inhibited hexaarylbiimidazole (HABI) derivative with markedly improved photochromic performance in coloration and decoloration rates as well as greater optical density in the colored state. The thermal bleaching rate (τ1/2 = 260 ms at 295 K) is the fastest among the reported ones for HABI derivatives.