New transition metal(II) complexes with naphthoate and aminoguanidine-based ligands: a combined spectroscopic and theoretical study with its applications

A new series of transition metal complexes of Mn(ΙΙ), Fe(ΙΙ), Co(ΙΙ) and Ni(ΙΙ) is synthesized from aminoguanidine and 3-hydroxy-2-naphthoic acid ligands with the formula (N4H7C)2[M{(C10H6(O)(COO)}2]·2H2O. The synthesized complexes were characterized by analytical, spectral and thermal studies. The elemental analysis confirms the composition of the complexes. The XRD studies show that all the complexes are isostructural in nature. The complexes were screened for antimicrobial activity against a Gram-positive, Bacillus subtilis (B. subtilis), and a Gram-negative, Escherichia coli (E. coli), bacterial species. The antibacterial results were concurrent with the output of the DFT investigation of metal complex, showing that the aminoguanidine moiety plays a key role in biological activity. Molecular docking studies have been carried out to identify the binding affinity and the mode of interaction of metal complexes with E. coli protein (2FUM). Further the synthesized complex is used as a single source precursor for preparation of nano metal oxides. The photocatalytic activity was carried out using the metal oxide as catalyst for degradation of dye materials. The metal oxide is found to be an efficient catalyst for degradation of methyl orange dye.</p