Synthesis and bio-activity of complex azo compounds: A review on formazans and its complexes

Formazans are well-known complexing agents and form highly stable complexes with verity of metals that are useful for number of pharmaceutical applications. The activity profile of formazans and their complexes are huge that include antibacterial, antifungal, antioxidant, anti-fertility, anti-tubercular, antiviral, anti-inflammatory, anticancer, anti-HIV, and anti-proliferative are among the biological activities covered by the formazans. The structures, synthesis, reactions, and spectral properties of formazans have been studied to highlight their potential applications in a variety of bioactive phenomena and analytical applications. The biological potential of the compounds will be greatly enhanced when substitution is carried out at R and R2. We observed that electron withdrawing groups at para position (if R, R1 & R2 = phenyl ring) are the best substitutions to achieve potent pharmacological activities.