Molecular Structure, Spectroscopic, Frontier Molecular Orbital Analysis, Molecular Docking Studies, and In Vitro DNA-Binding Studies of Osmium(II)-Cymene Complexes with Aryl Phosphine and Aryl Phosphonium Assemblies.

X-ray crystallography, spectroscopy, computational methods, molecular docking studies, and in vitro DNA-binding studies have been useful in the investigations of intermolecular and intramolecular interactions of osmium-cymene oxalato complexes with aryl phosphine and aryl phosphonium groups in both primary and secondary coordination spheres, respectively. Molecular structures of the novel complexes PPh4[Os(η6-p-cymene)Br(κ2-O,O'-C2O4)] (1) and [Os(η6-p-cymene) (κ2-O,O'-C2O4)PPh3] (2) were resolved by single-crystal X-ray diffraction (XRD). Primary and secondary coordination sphere contacts were investigated using Hirshfeld surface analysis which was supported by molecular docking (MD) studies. The MD data obtained predicted significant differences in binding energy across three receptors for the two osmium complexes. An in vitro DNA-binding study was accomplished using UV-Vis spectroscopy which showed that both 1 and 2 bond with DNA through an intercalation approach. The optimized molecular geometry, frontier molecular orbital (EHOMO and ELUMO) energies, global electrophilicity index (ω), chemical hardness (η), chemical potential (µ), and the energy band gap (EHOMO-ELUMO) were calculated utilizing density functional theory (DFT) methods. Computed structural parameters (bond lengths and angles) support the experimental single-crystal XRD data.

Prophylactic and Therapeutic Potential Zinc Metallodrugs Drug Discovery: Identification of SARS-CoV-2 Replication and Spike/ACE2 Inhibitors.

BACKGROUND: The emergence of severe acute respiratory syndrome coronavirus 2 (SARSCoV- 2) variants with novel spike protein mutations has been shown to be influencing the epidemiological and clinical aspects of the COVID-19 pandemic. OBJECTIVE: Due to studies showing various dietary benefits of zinc as a viral replication inhibitor as well as an immunity enhancer, organometallic complexes incorporating zinc ions can be ideal antiviral candidates due to their structural variation and diverse stereochemistry. METHODS: In silico studies were conducted for the virtual screening of zinc complexes with SARSCoV- 2 and host proteins to explore their effect on viral entry and replication activity. Molegro Virtual Docker along with AutoDock was used for the identification of potential SARS-CoV-2 inhibitor complexes from the Cambridge Structural Database (CSD). Molecular dynamics (MD), density functional theory (DFT), chemical absorption, distribution, metabolism, excretion, and toxicity properties (ADMET) were used to support the findings from virtual screening. RESULTS: In correlation with SARS-CoV-2 RNA-dependent RNA polymerase and spike receptorbinding domain bound with ACE2 docking results, the compound (bis(3,5-dimethyl-1H-pyrazole)- bis(2-furoato)-zinc(ii)) (CSD code ECOZAA) occurs to be a potential metal complex SARS-CoV-2 receptor inhibitor. The compound ECOZAA was observed (in silico binding affinity = - 179.29kcal/mol) to behave better than the clinically approved drug Remdesivir (in silico binding affinity = -62.69kcal/mol) against SARS-CoV-2 RNA-dependent RNA polymerase. The large HOMO- LUMO gap for the ECOZAA compound is an indication of the low chemical reactivity as well as the great kinetic stability of the compound. CONCLUSION: Thus, this study highlights the potential use of zinc metal complexes as SARS-CoV-2 viral entry and replication inhibitors.

A Co-Crystallised Cobalt(II) Cluster of Pyridinedicarboxylic Acid (PDC) as a Luminescent Material for Selective Sensing of Methanol.

A luminescent Cobalt(II) co-crystal [Co13(PDC)16(H2O)24.7H2O] 1 (where H2PDC = 2,6-pyridinedicarboxylic acid) have been prepared by oven-heating and slow evaporation of solvent. Single crystal X-ray diffraction (SCXRD) analysis revealed that 1 is a mixture of complexes that crystallizes in the triclinic space group P-1 and the geometry around the Co(II) ions is octahedral. The structure is extensively imbued with hydrogen bonding that helps in stabilizing the complex. Thermogravimetric analysis indicates that 1 is thermally stable up to 364 οC. The luminescence properties of 1 revealed a strong emission centered at 437 nm (λex = 345 nm) assigned to ligand to metal charge transfer (LMCT). The luminescence sensing of 1 towards volatile organic molecules were also examined. However, 1 displayed a turn off towards methanol compared to other molecules with high quenching efficiency and low limit of detection (3.5 × 10-4 vol%). The results show excellent selectively and high sensitivity. Powder X-ray diffraction studies revealed that the structural integrity of the complex was maintained after exposure to methanol vapour. Theoretical studies also revealed small binding energy (-413.2 au) and low energy gap (1.19) for 1-CH3OH adduct.

Crystal structure of bromido(η6-1-isopropyl-4-methylbenzene)(7-oxocyclohepta-1,3,5-trien-1-olato-κ2O,O')osmium.

In the title compound, [OsBr(C10H14)(C7H5O2)], the central OsII ion is ligated by a hexa-haptic η6p-cymene ring, a Br- ligand and two O atoms of a chelating tropolonate group. The p-cymene ligand presents more than one conformation, giving rise to a discrete disorder, which was modelled with two different orientations with occupancy values of 0.561 (15) and 0.439 (15). The crystal packing features C-H⋯O and C-H⋯Br hydrogen bonding. Aromatic π-π stacking inter-actions are also observed between adjacent non-benzenoid aromatic tropolone rings.