First-principles study for electrochemical sensing of neurotoxin hydrazine derivatives via h-g-C3N4 quantum dot

Abstract

The density functional theory (DFT) simulations were performed to understand the sensing behavior of heptazine-based graphitic (h-g-C3N4) quantum dot towards hydrazine (Hyd), dimethylhydrazine (DHy) and phenylhydrazine (PHy). The interaction energies illustrated that the high stability of the reported complexes was due to the presence of dominant dispersion forces, which was also revealed by symmetry-adapted perturbation theory (SAPT0) analysis. The domination of dispersion forces in stabilizing the complexes was also confirmed by the two quantitative approaches i.e., noncovalent interaction index (NCI) and quantum theory of atoms in molecules (QTAIM) analysis. The observed trend of interaction stability was PHy@h-g-C3N4>Hy@h-g-C3N4>DHy@h-g-C3N4. The electronic properties of the complexes were studied by Frontier Molecular Orbital (FMO), the density of state (DOS) and NBO charge transfer analyses. According to FMO analysis, the highest molecular orbitals (HOMOs) were shifted near to the Fermi level upon complexation, resulting in the lowering of the HOMO-LUMO energy gap (Egap). A significant charge transfer was noticed which reflected the increase in conductivity. Finally, the charge density was further explained by electron density differences (EDD) and charge decomposition analysis (CDA).