Design, synthesis, X-ray structure, Hirshfeld surface, and NLO behavior of 3-bromo-2-[(2E)-2-(2-oxonaphthalen 1(2H)-ylidene)hydrazinyl]benzoic acid

The crystalline form of the compound, 3-bromo-2-[(2E)-2-(2-oxonaphthalen-1(2H)-ylidene)hydrazinyl]benzoic acid (BOHB), has been synthesized in good yield by diazotization of 2-amino-3-bromobenzoic acid followed by a reaction with β-naphthol. The XRD-crystal measurements and DFT calculations confirmed that the hydrazone was the favored form. The structure of the synthetic product was also examined by IR and NMR spectroscopic methods. Using Hirshfeld surface analysis, interactions in the crystal have been highlighted, where many contributors are identified such as H···H (24.7%), O···H/H···O (20.6%), H···C/C···H (17.0%), and Br···H/H···Br (15.0%). Furthermore, the novel benzoic acid derivative was investigated for its nonlinear optical (NLO) properties. Computational results indicate that the compound shows enhanced first hyperpolarizability values relative to common reference systems. This suggests the benzoic acid derivative might offer a potential structural basis for exploring materials for selected NLO applications.