Divalent transition metal complexes of nitrogen, oxygen and sulfur containing ligand: design, structural, spectral, pH-metric, theoretical molecular modeling, analytical and mechanism studies

Abstract In the present study, 1-Nicotinoyl-4-phenyl thiosemicarbazide (H 2 NPT) multidentate nitrogen, oxygen and sulfur containing ligand is being synthesized in a simple single step reaction by condensing 1:1 molar ratio of ethanolic solutions both phenyl isothiocyanate nicotinoyl hydrazine. The prepared H NPT its complexes with Co 2+ , Ni Zn Cu were characterized pH-metric titrations, elemental analysis, FTIR, electronic spectra thermogravimetric (TGA) analyses. association constant stability constants calculated measurements 50% ethanol–water mixture. Also, DFT method was used to draw geometry all compounds parameters such as bond lengths, angles, dipole moment, Frontier orbitals (HOMO, LUMO), MEP other energetic (optical energy gap, softness, hardness, electronegativity) evaluated. reacted metal ions form colored precipitates that readily floated surface solution using oleic acid (HOL) surfactant vigorous shaking flotation cell. heavy metals' concentrations dissolved are determined flame atomic absorption spectrometry (FAAS). different affecting process thoroughly investigated, viz. pH sample solution, concentration ligand, HOL, temperature interfering ions. Nano-gram quantities 1500-ml samples quantitatively at 3.0–6.5 for 7.0–7.5 . these metals increased 300-fold. Interferences, on process, from various foreign avoided adding excess NPT. mode chelation between investigated proposed be through S, N and/or O atoms ligand. mechanism due an electrostatic interaction HOL formed metal–ligand H-bond formation. multi-element methodology has been utilized determination analytes certified reference materials, alloys, synthetic mixtures water recovery % more than 90% relative standard deviation (RSD), precision < 2%.