Cu(II)(PhOMe-Salophen) Complex: Greener Pasture Biological Study, XRD/HAS Interactions, and MEP

PhOMe-salophen ( 1b ) (salophen is N , N -bis(salycilidene)-1,2-phenylenediamine with two tert- butyl on each ring) and Cu(II) complex with PhOMe-salophen ( 1c ) have been synthesized and characterized using various tools, including X-ray diffraction for the Cu(II)-complex ( 1c , C 43 H 52 CuN 2 O 3 )). The copper complex has been obtained by Cu 2+ templated approach using 1b . PhOMe-salophen ( 1b ) has been obtained in reasonably high yield using a mixture of the Schiff-base, 1a, Pd(OAc) 2 , PPh 3 , Na 2 CO 3 , 4-methoxyphenylboronic acid in benzene. We focus in this research work on the electronic and structural properties of the Cu–Schiff base complex. The tetra-coordinate τ 4 index was calculated, indicating almost a perfect square planner in agreement with X-ray diffraction results. MEP reveals the maximum positive regions in 1/- associated with the azomethine and methoxyphenyl C–H bonds with an average value of 0.03 a.u. Hirshfeld surface analysis (HSA) was also studied to highlight the significant inter-atomic contacts and their percentage contribution through 2D Fingerprint plot. In a fair comparative molecular docking study, 1b and 1c were docked together with N -[{(5-methylisoxazol-3-yl)-carbonyl}alanyl}-l-valyl]- N 1-((1 R ,2 Z )-4-(benzyloxy)-4-oxo-1-[{(3 R )-2-oxopyrrolidin-3-yl}methyl]but-2-enyl)-l-leucinamide, N3 against main protease M pro , (PDB code 7BQY) using the same parameters and conditions. Interesting here to use the free energy, in silico, molecular docking approach, which aims to rank our molecules with respect to the well-known inhibitor, N3 . The binding scores of 1b , 1c , N3 are –7.8, –9.0, and –8.4 kcal/mol, respectively. These preliminary results propose that ligands deserve additional study in the context of possible remedial agents for COVID-19.