New nickel (II), cobalt (III), and iron (III) complexes with N′‐[(2‐aminochromon‐3‐yl)methylidene]benzohydrazide: Synthesis, characterization, solvatochromic shift, dipole moment, and DFT calculations

Abstract

AbstractNew Ni (II), Co (III), and Fe (III) complexes of hydrazone (HL) derived from 2‐aminochromone‐3‐carboxaldehyde with benzoyl hydrazine were synthesized and characterized by elemental analyses, spectral (UV–Vis, IR, Mass, 1H, and 13C‐NMR) data, as well as magnetic susceptibility, molar conductivity measurements, and thermal gravimetric analysis (TGA). The ligand behaves as monobasic with ONO donor sites, forming square planar geometry with Ni (II) and octahedral geometries with both Co (III) and Fe (III) complexes. Solvent effects on the absorption and fluorescence spectra of the prepared complexes were investigated in 11 different solvents with diverse polarities. Lippert–Mataga, Bakhshiev, Kawski–Chamma–Viallet, and Reichardt‐solvatochromic methods were applied to estimate the dipole moments of the ground and excited state (μg and μe). Multiple linear regression analysis was useful to specify the extent of specific and nonspecific solute–solvent interactions using Kamlet–Taft and Catalan solvatochromic models. The Stoke's shifts of complexes were mainly controlled by the polarity/polarizability parameter of the solvent. Density function theory (DFT) at B3LYP/6‐311G(d,p) level engaged in the Gaussian 09 program was carried out to optimize the structures of the ligand and its complexes. Structural parameters data are correlated with the experimental data. Also, using Coats–Redfern techniques, the kinetic parameters were calculated for each thermal degradation stage of metal complexes. Finally, in vitro bioassays of the ligand and its complexes against Gram‐negative, Gram‐positive bacteria and the fungus strain were tested for these compounds with good results.