Molecular simulation of a fluorescent sensor of 2-(1-H-benzoimidazole)-N-phenylcarbotiamide for selective detection of Ni2+ in aqueous media

In this computational study, 2-(1-H-benzoimidazole)-N-phenylhydrazine carbutiamide (L sensor) was reported as a highly sensitive nickel ion optical sensor. To investigate the selectivity of the ligand for metal ions, the structure of its complexes with different ions was optimised using the density functional theory (DFT) B3LYP/6-311G* (d,p) levels in solution phase (CPCM). Adsorption energy and cohesive energy were obtained in the presence of Ni2+ ions, respectively, -70.85 and 141.22 K cal/mol, which were the highest value obtained in the presence of cations. Electronic properties such as energy gap of metal ion complex with ligand, charge transfer between metal ion and ligand were studied and showed that the narrowest gap energy and highest charge transfer occurred between Ni2+ ion and ligand; so that the energy gap of the sensor decreased by 86% in the presence of Ni2+ ion. The optical properties of metal ion complexes with L-sensors were calculated and it was shown that the absorption of Ni2+ on the L-sensor changes its emission fluorescence to higher wavelengths and increases its intensity. Finally, using the QTAIM theory, it was determined that the N-11 and N-18 atomic basins are most sensitive to the presence of Ni2+ ion.