Novel photochromic system derived from tetracyanoquinodimethane and pyrazoles

Purpose To discover new photochromic molecules suitable for various applications. Design/methodology/approach The synthesis of the new photochromic pyrazole derivatives was accomplished by reaction of tetracyanoquinodimethane (TCNQ) and pyrazoles in polar solvents such as dimethylformamide (DMF). Findings A new photochromic system had been developed and the synthesis and photochromic properties of three pyrazole derivatives upon irradiation with ultraviolet light were studies in different solvents. The photochromic and thermochromic properties were affected markedly upon changing the solvent polarity. The new materials gave colourless to deep yellow coloration upon irradiation with ultraviolet, rendering them suitable candidates for optical storage media using the region of 400 nm. Practical implications A new photochromic system had been developed via a simple method. The new compounds showed photochromic, thermochromic, and solvatochromic properties making them potential candidates for many applications such as sensors, optical data storage, sensors and heat sensitive materials. Originality/value The photochromic system was novel and hence the photochromic molecules were novel.