Synthesis, characterization of polymeric ligand-metal complexes and their biological activity properties

Abstract

New members are joining to the Schiff bases family every day. In our study, firstly a new Schiff base was abbreviated as ligand (L) that was synthesized via condensation reaction between 3-aminonaphtalen-2-ol and 2,3-dihydroxybenzaldaheyde. Then, poly-ligand (PL) was obtained in basic medium in the presence of ammonium persulfate (NH4)2S2O8 via poly-condensation reaction by using L. Metal complexes were synthesized from the interaction of PL with various metal species such as Zn2+, Hg2+, Ni2+, Pb2+and Cu2+. The structures of compounds were confirmed by FT-IR, UV–Vis, 1HNMR and elemental analysis. Their SEM images were recorded at different sizes. Looking at the SEM images, it can be seen that the [Hg(PL)2] metal complex is similar to the red blood cells. Thermal analyses of PL and its metal complexes [M(PL)2] were performed. The biological properties such as DNA binding-cleavage, antioxidant and antibacterial activities of all synthesized compounds were investigated. According to the results, it was determined that such properties of its metal complexes were better than PL. For example, when the oxidative cleavage activity was examined, it was determined that [Cu(PL)2] complex completely cleaved the DNA and also it denatured all DNA at higher concentrations (≥100 ppm). DNA binding for the poly-ligand and its metal complexes bounded to CT-DNA in electrostatic mode. The antioxidant activity results showed that [Hg(PL)2] complex had a high inhibition value of 78.70±0.55% at 100 ppm. The [Hg(PL)2] complex was much more effective against all bacterial strains. The antibacterial activity of [Cu(PL)2] and [Zn(PL)2] complexes showed the highest activity against B. subtilis strain at the concentration of 62.5 µg/mL. DNA binding was determined from the UV–Vis spectra of the interaction of the PL and its metal complexes with CT-DNA. According to these UV–Vis results, it can be said that the poly-ligand and its metal complexes bounds to CT-DNA in electrostatic mode.