Structural and Computational Studies of Cobalt(II) and Copper(II) Complexes with Aromatic Heterocyclic Ligand

Abstract

Two coordination complexes, a cobalt(II) complex tris(1,10-phenanthroline)-cobalt perchlorate hydrate, [Co(phen)₃]·(ClO₄)₂·H₂O(1), and a copper(II) complex tris(1,10-phenanthroline)-copper perchlorate 4-bromo-2-{[(naphthalene-1-yl)imino]methyl}phenol hydrate, [Cu(phen)₃]·(ClO₄)₂·HL·[O] (2), [where, phen = 1,10-phenathroline as aromatic heterocyclic ligand, HL = 4-bromo-2-((Z)-(naphthalene-4-ylimino) methyl) phenol] have been synthesized and structurally characterized. Single crystal X-ray analysis of both complexes has revealed the presence of a distorted octahedral geometry around cobalt(II) and copper(II) ions. density functional theory (DFT)-based quantum chemical calculations were performed on the cationic complex [Co(phen)₃]²⁺ and copper(II) complex [Cu(phen)₃]²⁺ to get the structure property relationship. Hirshfeld surface and 2-D fingerprint plots have been explored in the crystal structure of both the metal complexes. To find potential SARS-CoV-2 drug candidates, both the complexes were subjected to molecular docking calculations with SARS-CoV-2 virus (PDB ID: 7BQY and 7C2Q). We have found stable docked structures where docked metal chelates could readily bound to the SARS-CoV-2 M^pro. The molecular docking calculations of the complex (1) into the 7C2Q-main protease of SARS-CoV-2 virus revealed the binding energy of −9.4 kcal/mol with a good inhibition constant of 1.834 µM, while complex (2) exhibited the binding energy of −9.0 kcal/mol, and the inhibition constant of 1.365 µM at the inhibition binding site of receptor protein. Overall, our in silico studies explored the potential role of cobalt(II) complex (1), and copper(II) complex (2) complex as the viable and alternative therapeutic solution for SARS-CoV-2.

Keywords:

• crystal structures
• DFT calculations
• Hirshfeld surface analysis
• metal complexes
• SARS-CoV-2

Acknowledgment

We wish thanks to SAIF, IIT Madras for Single crystal X-ray analysis of complex (1) and (2).

The authors are also thankful to the Head, Chemistry Department, National Institute of Technology Patna for providing computational resources and spectral analysis. We must thanks to SAIF, IIT Patna, India for NMR and HRMS analysis. One of the author (Aprajita) thanks to CSIR, New Delhi, India for awarding JRF fellowship (File no. 09/1278(0003)/2020-EMR-I).

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Credit authorship contribution statement

Aprajita ([email protected]): Synthesis, Formal analysis and investigation, software, Writing-original draft, Resources. Mukesh Choudhary ([email protected]): Supervision, Conceptualization, Visualization, Methodology.