Design and development of several polymeric metal-organic frameworks, spectral characterization, and their antimicrobial activity

Coordination polymers were obtained by the reaction of metal acetates, M(CH3COO)2·xH2O {where M = Mn(II), Co(II), Ni(II) and Cu(II)} with AFP ligand (AFP = 5,5'-(piperazine-1,4-diylbis(methylene))bis(2-aminobenzoic acid). The AFP ligand was prepared by the one-pot, two-step reaction of formaldehyde, 2-aminobenzoic acid, and piperazine. Structural and spectroscopic properties have been studied by elemental, spectral (FT-IR, 1H NMR, 13C NMR, and UV-vis), and thermogravimetric analysis. UV-vis spectra and magnetic moment values indicate that Mn(II), Co(II), and Ni(II) polymer-metal complexes are octahedral, while Cu(II) and Zn(II) polymer-metal complexes are distorted octahedral and tetrahedral, respectively. The analytical data confirmed that the coordination polymers of Mn(II), Co(II), Ni(II), and Cu(II) are coordinated with two water molecules, which are further supported by infrared spectra and thermogravimetric analysis data. The prepared polymer-metal complexes showed good antibacterial activities against all tested microorganisms; however, the AFP ligand was also found to be effective, but relatively less than their polymer-metal complexes. Along with antibacterial activity, all the polymer-metal complexes exhibit significant antifungal activity against most of the tested fungal strains. The results of antimicrobial activity reveals that the AFP-Cu(II) showed the highest antibacterial and antifungal activity than other polymer-metal complexes.