Experimental and Theoretical Investigation of 3‐[(2‐chlorophenyl)diazenyl]pyridine‐2,6‐diamine as Optical Limiter

Azobenzenes undergo reversible trans‐cis photoisomerization and have been extensively studied as photoresponsive material. In contrast, azopyridines have garnered relatively less attention despite their similar photochemistry. When compared to azobenzene, azopyridines offer more opportunities for material design through hydrogen bonding and coordination chemistry. Here, we report the isomerization for 3‐[(2‐chlorophenyl)diazenyl]pyridine‐2,6‐diamine ( 1od ) through an integrative experimental and computational study. Notably, the energy barrier of 1od was significantly lower than that of previously reported azobenzenes. Moreover, we investigated and elucidated the photoisomerization pathway. 1od exhibited high nonlinear absorption, with a nonlinear absorption coefficient (β eff ) of 1.31 10 −9 m W −1 , as determined by Z‐scan measurements. The results indicate that 1od has potential applications in optical limiters, which are used to fabricate protective eyewear and safeguard optical sensors from damage.