Table 3.

The docking of PDBS, CPBS, (FePDBS (H2O) NO₃), and (FeCPBS (H₂O)NO₃) with the active sites of the COVID-19 major protease viral protein receptor was studied (PDB ID: 6lu7).

Interaction		Distance (Å)	Receptor	E (kcal/mol)
CPBS
O 23	H-donor	2.94 (1.96)	O LEU 287	−4.2
Br 26		3.35	O THR 169	−1.5
6-ring	pi-H	3.51	CE LYS 137	−0.5
		3.97	CB ASP 197	−0.7
[FeCPBS(H2O)NO3]
O 37	H-donor	2.79 (1.77)	OD1 ASN 142	−15.7
Br 27		3.50	O THR 26	−0.7
O 40	H-acceptor	3.10 (2.17)	NE2 GLN 189	−1.1
6-ring	pi-H	3.96	CA ASN 142	−0.5
PDBS
O 24	H-donor	2.92 (1.94)	O THR 196	−3.5
6-ring	pi-H	4.80	CB PRO 132	−0.6
		3.87	CA ASN 133	−0.5
[FePDBS(H2O)NO3]
O 37	H-donor	2.80 (1.90)	O LEU 272	−13.3