Photochromic organogel based on [2.2]paracyclophane-bridged imidazole dimer with tetrapodal urea moieties

A novel photochromic organogelator possessing [2.2]paracyclophane-bridged imidazole dimer unit with four hydrogen bonding urea arms was obtained. Irradiating UV light to benzene solution of the photochromic organogelator, rapid photochromism from colorless to green is observed. From the transient vis–NIR absorption measurement, a characteristic absorption around 400 nm and a broad absorption from 500 to 1000 nm can be attributed to the colored species. The half-life of the colored species is 243 ms at 298 K. In cyclohexane, the organogel was successfully formed, which was characterized by SEM observation and IR spectroscopy and showed fast photochromism even in the gel phase.