Development of Bioactive Macrocyclic Ligands: A Comparative Study on Ni(II) and Co(II) Complexes
Author : Basant Kumar Kashyap
Abstract :
A novel metformin–quinoline Schiff base ligand was synthesized by the condensation of metformin with a quinoline aldehyde derivative, followed by the preparation of its Chromium(II) and Zinc(II) complexes. The synthesized compounds were characterized by elemental analysis, FT–IR, UV–Visible spectroscopy, ¹H NMR, ESI–MS, PXRD, SEM–EDX, and TGA/DTA. The results confirmed successful Schiff base formation and coordination of both metal ions through nitrogen donor atoms, leading to stable coordination frameworks.
Density Functional Theory (DFT) calculations showed that metal coordination enhanced electronic delocalization and reduced the HOMO–LUMO energy gap, in agreement with the experimental findings. Molecular docking revealed favourable binding interactions with the selected biological target, while ADMET prediction indicated acceptable drug-like and pharmacokinetic properties.
Biological evaluation demonstrated that both metal complexes exhibited higher antimicrobial and antioxidant activities than the free ligand, with the Chromium(II) complex showing the greatest activity. The enhanced biological performance is attributed to increased lipophilicity, improved electronic delocalization, and the chelation effect.
Overall, the combined experimental and computational results demonstrate that metformin–quinoline-based Chromium(II) and Zinc(II) Schiff base complexes are promising bioactive coordination compounds with potential for further development as metal-based therapeutic agents.
Keywords :
Schiff base, Metformin, Quinoline, Chromium(II), Zinc(II), DFT, Molecular docking, ADMET, Antimicrobial activity, Antioxidant activity.
