Novel dinuclear Ni (II) Schiff base complexes induced noncovalent exchanges: Crystal structure investigation, electrochemical assessment, Hirshfeld surface analysis and SARS-CoV-2 docking study

In this work, novel Ni (II) complexes, namely, [Ni₂(L)₂(OAc)₂(EtOH)₂] (1a), [Ni₂(L)₂(OAc)₂(H₂O)₂] (1b-1) and [Ni₂(L)₂(OAc)₂(EtOH)₂] (1b-2) as co-crystal were synthesized by the 1:1 condensation (https://www.sciencedirect.com/topics/chemistry/condensation) of Ni (CH₃COO)₂·4H₂O and Schiff base ligand (H₂L) (2-hydroxy-4-methoxybenzaldehyde and 2-amino-2-methylpropanol). The ligand based on Schiff base and fabricated complexes (1a) and (1b-1 and 1b-2) were successfully identified by CHN assessment, FT-IR, UV–Vis spectra, melting point and CV voltammogram. The electrochemical behavior investigation shows that the nickel complexes exhibited irreversible oxidation processes in methanol solution. Additionally, the crystal structures of complexes (1a) and (1b) have been recognized by single-crystal X-ray diffraction investigation. It turned out that the complexes (1b-1) and (1b-2) crystallize together, making a co-crystal 1b with an additional EtOH solvent molecule in the crystal structure. A detailed study of intermolecular exchanges was performed using attractive graphical analysis tools such as three-dimensional Hirshfeld surfaces analysis, two-dimensional fingerprint plots (FPs), and enrichment ratios (E), which make C-H … C, C-H … O hydrogen bond, C … O, H … H, and O … O short contacts on Hirshfeld surfaces with color code are observed. Moreover, an appraisement of the inhibitory trace against coronavirus (main protease SARS-CoV-2, PDB ID: 6Y2F) and molecular targets of human angiotensin-converting enzyme-2 (ACE-2) was performed by a molecular docking study in which two nickel complexes performed best for PDB protein ID: 6M0J and all three complexes for PDB protein ID: 6Y2F.