Structural, Hirshfeld surface and molecular docking studies of a new organotin(IV)-phosphoric triamide complex and an amidophosphoric acid ester proposed as possible SARS-CoV-2 and Monkeypox inhibitors

Phosphoramides and their complexes are attractive compounds due to their significant inhibiting functionality in biological medicine. In this paper, a novel organotin(IV)-phosphoramide complex (Sn(CH₃)₂Cl₂{[(3-Cl)C₆H₄NH]P(O)[NC₄H₈O]₂}₂, 1), derived from a reaction between phosphoric triamide ligand with dimethyltin dichloride, and a new amidophosphoric acid ester ([OCH₂C(CH₃)₂CH₂O]P(O)[N(CH₃)CH₂C₆H₅], 2), prepared from the condensation of a cyclic chlorophosphate reagent with N-methylbenzylamine, are structurally characterized and in silico investigated as potential SARS-CoV-2 and Monkeypox inhibitors by molecular docking simulation. Both compounds crystallize in the monoclinic crystal system with space group P2₁/c. The asymmetric unit of the complex 1 consists of one-half molecule, where Sn^IV is located on an inversion center, while the asymmetric part of 2 consists of one whole molecule. In the complex 1, the tin atom adopts a six-coordinate octahedral geometry with trans groups of (Cl)₂, (CH₃)₂ and (PO)₂ (PO = phosphoric triamide ligand). The molecular architecture consists of the N-H⋯Cl hydrogen bonds stretching as a 1D linear arrangement along the b axis with intermediate R22(12) ring motifs, whereas in the case of 2, the crystal packing is devoid of any classical hydrogen bond interaction. Furthermore, a graphical analysis by using Hirshfeld surface method identifies the most important intermolecular interactions being of the type H⋯Cl/Cl⋯H (for 1) and H⋯O/O⋯H (for 1 and 2), covering the hydrogen bond interactions N-H⋯Cl and C-H⋯O═P, respectively, which turn out to be favoured. A biological molecular docking simulation on the studied compounds provides evidence to suggest a significant inhibitory potential against SARS-COV-2 (6LU7) and Monkeypox (4QWO) especially for 6LU7 with a binding energy around -6 kcal/mol competing with current effective drugs against this virus (with a binding energy around -5 and -7 kcal/mol). It is worth noting that this report is the first case of an inhibitory potential evaluation of phosphoramide compounds on Monkeypox.

Structural and Molecular Packing study of Three New Amidophosphoric Acid Esters and Assessment of Their Inhibiting Activity Against SARS‐CoV‐2 by Molecular Docking

Three new compounds of amidophosphoric acid esters with a [OCH₂C(CH₃)₂CH₂O]P(O)[X] segment (where X=cyclopentylamido (1), 2‐aminopyridinyl (2) and pyrrolidinyl (3)) were synthesized and studied using FT‐IR and ³¹P/¹³C/¹H NMR spectroscopies and single‐crystal X‐ray diffraction analysis. The compounds crystallize in the triclinic space groups P1‾ for 1 and 3 and in the orthorhombic space group Pca2₁ for 2, where the asymmetric unit consists of three symmetrically‐independent molecules for 1 and one molecule for 2 and 3. The intermolecular interactions and supramolecular assemblies are assessed by Hirshfeld surface analysis and enrichment ratios. The results reveal that the substituent effect plays an important role in directing the supramolecular structures. The presence of the aromatic substituent aminopyridine in 2 providing the C−H…π interactions leads to a larger variety in interactions including H…H, H…O/O…H, H…C/C…H and H…N/N…H contacts, whereas the packings of the compounds 1 and 3 bearing aliphatic substituents only include H…H and H…O/O…H contacts. The enrichment ratios affirm the importance of O…H/H…O contacts reflecting the hydrogen bond N−H…O interactions to be the enriched contacts. Compounds 1–3 were also investigated along with five similar reported structures with a [OCH₂C(CH₃)₂CH₂O]P(O) segment for their inhibitory behavior against SARS‐CoV‐2. The molecular docking results illustrate that the presence of the aromatic amido substituent versus the aliphatic type provides a more favorable condition for their biological activities.