Exploring the optical properties of novel pyridazin-3(2H)-one derivatives - A combined experimental and computational study

Abstract

• Three pyridazinone derivatives were synthesized and characterized by FT-IR, 1 H-NMR, 13 C-NMR and ESI-MS. • Computational studies were performed by B3LYP/6-31+g(d,p) level. • TD-DFT calculations are adopted to construct theoretical absorption spectra in the solvent phase which is compared with the experiments. • Synthesized compounds were studied for their optical properties in solution and solid phases. Three novel fluorophores i.e. (E)-4-(2-chlorobenzyl)-6-(4-chlorostyryl)pyridazin-3(2H)-one (4a) , (E)-6-(4-chlorostyryl)-4-(4-methoxybenzyl)pyridazin-3(2H)-one (4b) and (E)-4-benzyl-6-(4-chlorostyryl)pyridazin-3(2H)-one (4c) were synthesized and characterized by FT-IR, 1 H-NMR, 13 C-NMR and mass spectrometry . To gain insights into the structure-property relationship, a detailed computational study is taken up here at the B3LYP/6-31+g(d,p) level. Frontier molecular orbital (FMO) analysis and natural bond orbital analysis (NBO) are done on the optimized geometries to evaluate the reactivity and stability of the molecules. Electrostatic potential maps offer the charge distribution in these molecules. Time-dependent density functional theory calculations are adopted to construct theoretical absorption spectra in the solvent phase which is compared with the experiments. In addition, the synthesized compounds were studied for their optical properties in solution and solid phases. Consequently, the fluorophores studied, show emissions, which cover a spectral range, going from 416 nm for compound 4b to 418 nm for 4c and 421nm for compound 4a .