Photo Switchable Hexaarylbiimidazoles for Potential use in Switching Technologies Applications
We report the synthesis and optical properties of a novel hexaarylbiimidazoles (HABIs) molecular switches. The
light pink color of hexaarylbiimidazole (HABI) in benzene and in polymer films obtained with ultra violet irradiation showed
new absorption band at 531 nm. whereas, the light-yellow solution of bridged hexaarylbiimidazole (B-HABI) in benzene
quickly turned green under ultra violet irradiation and showed new absorption band at 594 nm. Kinetic study shows that the
photodissociation process is faster in B-HABI, and the thermal recombination is faster in HABI. Also, we found that the
photodissociation and thermal recombination process decreased with annealing in HABI doped in polymer films. HABI
exhibit great stability with 101 repetitive switching cycles in benzene, the absorbance of radical species decreased to 50 %
after 97 cycles.
Index Terms— Photochromism, thermochromism, kinetics, fatigue resistance.