Crystal structure, molecular docking with SARS-CoV-2 receptors, and potential drug property of tetrahedral Zn(II) complexes

The recent global pandemic by the outbreak of the SARS-CoV-2 virus caused about seven million deaths worldwide. The WHO approved the repurposing of antiviral drugs as the treatment protocol for COVID-19. Yet, it was insufficient to stop the outbreak of COVID-19. By virtue of a broad spectrum of variable oxidation numbers, geometries, tuneable redox, and kinetic and thermodynamic properties, transition metal complexes offer themselves as a viable alternative to the antiviral drugs against SARS-CoV-2. The computational methods in biology and chemistry are a promising starting point in this regard. Here, we present the synthesis, crystal structure, docking study with SARS-CoV-2 receptors, and potential drug property of two tetrahedral Zn(II) complexes, viz. [Zn(µ₂-Bz)₃]_n (1) and [Zn(Phen)Cl₂]₂ (2) (Bz = benzoate ion, Phen = 1,10-phenanthroline). They were synthesized at room temperature and characterized by elemental analyses, FT-IR spectroscopy, thermal analysis (TGA/DTG), powder X-ray diffraction (PXRD), and single crystal X-ray diffraction. Complex 1 is a coordination polymer with unusual triply-bridged triangular secondary building unit (SBU), whereas complex 2 is a novel supramolecular dimer. The crystal structures of 1 and 2 are stabilized by a number of supramolecular interactions, which ultimately lead to a 3D architecture for each of them. Their crystal packing is discussed in details, with inputs from energy calculations, by the analysis of electrostatic potential mapped on the Hirshfeld surface and two-dimensional (2D)-fingerprint plot by CrystalExplorer. A molecular docking study of the synthesized complexes was performed against seven important proteins of SARS-CoV-2. ADMET calculations were used to evaluate their drug potential.