Synthesis, characterization and biological studies of a sterically hindered symmetrical nitrogen donor ligand and its metal complexes

A new sterically hindered Schiff base ligand (SN-NNDMB) was synthesized from meso-1,2-diphenyl ethylenediamine (meso-stien) and 4-N,N'-dimethylaminobenzaldehyde. Its structure was determined by single-crystal X-ray diffraction data. The crystal structure of the organic ligand was found to be triclinic, space group P-1 with a = 6.1407(8) angstrom, b = 8.8372(12) angstrom, c = 12.0006(15) angstrom, alpha = 103.882(7)degrees, beta = 95.325(8)degrees, gamma = 91.082(7)degrees, F(0 0 0) = 254, Dc = 1.253 Mg/m(3), mu = 0.571 mm(-1), R = 0.0399, and wR = 0.1019. Co, Ni, Cu and Zn complexes of SN-NNDMB were also prepared and characterized by elemental analysis, IR-, mass-, NMR- and electronic- spectra, magnetic moment, molar conductance, powder XRD, and TGA. The obtained results show that the Schiff base ligand acts as a bidentate, coordinated through the azomethine nitrogen atoms. According to the biotest such as Antimicrobial, DNA binding, DNA cleaving, Anti-tubercular, Anticancer, and SOD-like activity, the compounds showed better activity after chelation. The Cu(II)-SN-NNDMB complex showed the highest bioactive potential amonst the analyzed compounds. (C) 2021 Elsevier Ltd. All rights reserved.