Synthesis, molecular structure, anti-microbial, anti-oxidant and enzyme inhibition activities of 2-amino-6-methylbenzothiazole and its Cu(II) and Ag(I) complexes

Molecular structure of 2-amin-6-methylbenzothiazole, 1 and its coordination complexes with Ag(I) and Cu(II) were determined by X-ray diffraction. The ligand 2-amin-6-methylbenzothiazole (hereafter represented as L in general formula of complexes) and [AgL2]NO3 crystallize in orthorhombic crystal systems and CuL2(OAc)(2) complex is monoclinic. Ligand and its Ag(I) complex possess space groups Pbcn and Cu(II) complex has a space group P2(1)/c. Complex bis(2-amino-6-methylbenzothiazole)diacetatocopper(II), 2 and bis(2-amino-6-methylbenzothiazole)silver(I) nitrate, 3 were obtained by reacting ligand with respective metal salt in a molar ratio 2:1, respectively. The coordination environment of copper metal is octahedral where acetate acts as bidentate ligand and 2-amino-6-methylbenzothiazole occupies trans position with respect to each other. The ligand contains three possible coordination sites (endocyclic nitrogen, exocyclic nitrogen and sulphur). Among three nucleophilic centers the endocyclic nitrogen is more basic and readily coordinates to the metal ion (both Cu and Ag). Nitrate group plays an important role in stabilizing the supramolecular structure of Ag complex wherein NO center dot center dot center dot H2N- interactions are very effective. Non-covalent interactions in molecules make them efficient medicines. On the basis of certain secondary interactions, compounds 1-3 were expected to be biologically active and were studied as antibacterial, antifungal, antioxidant agents and enzyme inhibitors. Moderate activities against selected strains were observed for the ligand and its complexes. It was observed that the antibacterial and antifungal potentials of the ligand were enhanced by complexation with copper(II) and silver(I) metal ions. (C) 2019 Elsevier B.V. All rights reserved.