Dinuclear Phenoxo-Bridged Nickel(II) and Copper(II) Complexes of Phenolate-Based Tripodal Ligand: Theoretical and Experimental Insights

Three dinuclear complexes of composition [Ni-2(II)(L)(2)][ClO4](2) and [Cu-2(II)(L)(2)(OClO3)(2)](.)3H(2)O have been synthesized using a new tripodal ligand [(2-pyridyl)methyl](2-benzyl)-aminomethyl}-phenol (HL)], in its deprotonated form, providing a N2O donor set. Crystallographic analyses reveal that [Cu-2(II)(L)(2)(OClO3)(2)](.)3H(2)O has a diphenoxo-bridged structure. In [Cu-2(II)(L)(2)(OClO3)(2)](.)3H(2)O, each metal center is (MN2O3)-N-II-coordinated with a square-pyramidal environment for each copper(II) center. In this work, the molecular structure, harmonic vibrational frequencies and UV-Vis of [Ni-2(II)(L)(2)](2+) and [Cu-2(II)(L)(2)](2+) has been explored. With the help of density functional theory (DFT)/B3LYP techniques and LANL2DZ as a basis set, the ground-state molecule shape and vibrational frequencies were computed. The basic vibrations were allocated using the VEDA program to compute the potential energy distribution (PED) of the vibrational modes. The band gap energies of the title complexes ([Ni-2(II)(L)(2)](2+) and [Cu-2(II)(L)(2)](2+)) are 3.21 eV and 1.59 eV, respectively, according to HOMO-LUMO energies. The maximal absorption wavelength and band gap energy of the title complexes were calculated theoretically using the UV absorption spectra. MEP analysis identifies electrophilic and nucleophilic sites. Hirshfeld surface analysis was used to characterize the 3D intermolecular interactions in ([Ni-2(II)(L)(2)](2+) and [Cu-2(II)(L)(2)](2+)) of the crystal surface, whereas fingerprint plots were used to explain the 2D interactions. The biological activity of the complexes was investigated using molecular docking.