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Mixed ligand complexes of Pd(II) and Cd(II) with N-picolyl-amine dithiocarbamate (PAC-dtc) as primary ligand and tertiary phosphine ligand as secondary ligands have been synthesized and characterized via elemental analysis, molar conductance, NMR (1H and 31P), and IR techniques. The PAC-dtc ligand displayed in a monodentate fashion via sulfur atom whereas diphosphine ligands coordinated as a bidentate mode to afford a square planner around the Pd(II) ion or tetrahedral around the Cd(II) ion. Except for complexes [Cd(PAC-dtc)2(dppe)] and [Cd(PAC-dtc)2(PPh3)2], the prepared complexes showed significant antimicrobial activity when evaluated against Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans and Aspergillus niger. Moreover, DFT calculations were performed to investigate three complexes {[Pd(PAC-dtc)2(dppe)](1), [Cd(PAC-dtc)2(dppe)](2), [Cd(PAC-dtc)2(PPh3)2](7)}, and their quantum parameters were evaluated using the Gaussian 09 program at the B3LYP/Lanl2dz theoretical level. The optimized structures of the three complexes were square planar and tetrahedral geometry. The calculated bond lengths and bond angles showed a slightly distorted tetrahedral geometry for [Cd(PAC-dtc)2(dppe)](2) compared to [Cd(PAC-dtc)2(PPh3)2](7) due to the ring constrain in the dppe ligand. Moreover, the [Pd(PAC-dtc)2(dppe)](1) complex showed higher stability compared to Cd(2) and Cd(7) complexes which can be attributed to the higher back-donation of Pd(1) complex.

This paper explores a dual inhibition of main protease (Mpro) and nonstructural protein 10/nonstructural protein 16 (NSP16) methyltransferase complex as the key targets for COVID-19 therapy. These are based on the new Schiff-base ligand that was obtained from the condensation of (4-chloro-3-methyl phenyl) hydrazine with 2-pyridine-carboxaldehyde and its novel Schiff-base metal complexes. These include Ni(II), Pd(II), Pt(II), Zn(II), and Hg(II). The newly synthesized compounds have been characterized using FT-IR, 1H NMR, 13C NMR, and elemental analysis. The results suggested that the Schiff-base ligand is coordinated as a bidentate ligand through the nitrogen atoms of the azomethine group and pyridyl ring. In addition, the biological activity of the prepared complexes was examined against Pseudomonas aeruginosa and Staphylococcus aureus, and the results showed that the Zn(II) complex has the highest activity compared with other compounds. The active sites were found by looking at the molecular electrostatic potential (MEP) maps of the above ligands and complexes. The activity of the compound and its Ni(II) and Zn(II) complexes against Mpro and NSP10/ NSP16 was investigated using a molecular docking approach. They showed excellent binding energies ranging from −5.9 to −7.2 kcal/mol and −5.8 to −7.2 for Mpro and NSP16, respectively. All conformers of the metal complexes were docked with the active site of the NSP16 receptor, showing a binding affinity of 100%. According to our knowledge, this was the first report of these metal complexes as dual inhibitors for Mpro and NSP16 of SARS-CoV-2.

Ten mixed‐ligand phenyl mercury(II) complexes containing 1‐methyl‐1H‐tetrazole‐5‐thiol (HmtzS) (1) and phosphine or amine ligands. These complexes fall into two groups: [PhHg(mtzS){Ph2P(CH2)PPh2}]2 (2) and [PhHg(mtzS){Ph2P(CH2)nPPh2}] (3‐6), where n varies, and [PhHg(mtzS)(diamine)] (8‐10), with diamine choices being 2,2′‐bipyridyl (Bipy, 8), 1,10‐phenathroline (Phen, 9), or ethylenediamine (en, 10). These complexes were synthesized with moderate to high yields and characterized using various techniques. Characterization data revealed that the mtzS− ligand coordinates as a monodentate ligand through the thiolate sulfur atom in all complexes, adopting a tetrahedral geometry around the Hg(II) center. Furthermore, complexes [PhHg(mtzS)] (1) and its diamine derivatives (8‐10) were assessed for hydrogen storage at 77 K using the VTI method. Results demonstrated that the incorporation of diamines improves hydrogen storage capacity at low pressure. The precursor stored (1) 2.3 wt.% at 80 bar, while the other complexes showed storage capacities ranging from 2.9 to 3.86 wt.% at pressures of 45‐60 bar. Thermodynamic properties of the [PhHg(mtzS)(Bipy)] complex was calculated at three different temperatures. The results prove that the entropy was equal to 0.50543599 J/mol H2. K while the enthalpy equal to 0.0942638 KJ/(mol H2). [ABSTRACT FROM AUTHOR]

Mixed ligand complexes of Pd(II) and Cd(II) with N-picolyl-amine dithiocarbamate (PAC-dtc) as primary ligand and tertiary phosphine ligand as secondary ligands have been synthesized and characterized via elemental analysis, molar conductance, NMR (1H and 31P), and IR techniques. The PAC-dtc ligand displayed in a monodentate fashion via sulfur atom whereas diphosphine ligands coordinated as a bidentate mode to afford a square planner around the Pd(II) ion or tetrahedral around the Cd(II) ion. Except for complexes [Cd(PAC-dtc)2(dppe)] and [Cd(PAC-dtc)2(PPh3)2], the prepared complexes showed significant antimicrobial activity when evaluated against Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans and Aspergillus niger. Moreover, DFT calculations were performed to investigate three complexes {[Pd(PAC-dtc)2(dppe)](1), [Cd(PAC-dtc)2(dppe)](2), [Cd(PAC-dtc)2(PPh3)2](7)}, and their quantum parameters were evaluated using the Gaussian 09 program at the B3LYP/Lanl2dz theoretical level. The optimized structures of the three complexes were square planar and tetrahedral geometry. The calculated bond lengths and bond angles showed a slightly distorted tetrahedral geometry for [Cd(PAC-dtc)2(dppe)](2) compared to [Cd(PAC-dtc)2(PPh3)2](7) due to the ring constrain in the dppe ligand. Moreover, the [Pd(PAC-dtc)2(dppe)](1) complex showed higher stability compared to Cd(2) and Cd(7) complexes which can be attributed to the higher back-donation of Pd(1) complex. [ABSTRACT FROM AUTHOR]

This paper explores a dual inhibition of main protease (Mpro) and nonstructural protein 10/nonstructural protein 16 (NSP16) methyltransferase complex as the key targets for COVID-19 therapy. These are based on the new Schiff-base ligand that was obtained from the condensation of (4-chloro-3-methyl phenyl) hydrazine with 2-pyridine-carboxaldehyde and its novel Schiff-base metal complexes. These include Ni(II), Pd(II), Pt(II), Zn(II), and Hg(II). The newly synthesized compounds have been characterized using FT-IR, 1H NMR, 13C NMR, and elemental analysis. The results suggested that the Schiff-base ligand is coordinated as a bidentate ligand through the nitrogen atoms of the azomethine group and pyridyl ring. In addition, the biological activity of the prepared complexes was examined against Pseudomonas aeruginosa and Staphylococcus aureus, and the results showed that the Zn(II) complex has the highest activity compared with other compounds. The active sites were found by looking at the molecular electrostatic potential (MEP) maps of the above ligands and complexes. The activity of the compound and its Ni(II) and Zn(II) complexes against Mpro and NSP10/ NSP16 was investigated using a molecular docking approach. They showed excellent binding energies ranging from −5.9 to −7.2 kcal/mol and −5.8 to −7.2 for Mpro and NSP16, respectively. All conformers of the metal complexes were docked with the active site of the NSP16 receptor, showing a binding affinity of 100%. According to our knowledge, this was the first report of these metal complexes as dual inhibitors for Mpro and NSP16 of SARS-CoV-2. [ABSTRACT FROM AUTHOR]

Four palladium(II) and mercury(II) complexes of the type [MCl2(HPAO)] or [M(PAO)2](HPAO = syn‐2‐pyridine aldoxime) are prepared and characterized using FTIR, 1H NMR spectra, molar conductivity, and melting point. The results demonstrated that a chelating bidentate behavior of APO through the indo and exocyclic nitrogen atoms. The applicability of the prepared complexes in hydrogen storage at a temperature of 77 K and a pressure of 100 bar is studied. The results show that the complexes are capable of storing hydrogen as follows: 1.54, 2.3, 0.53, and 0.63 wt.% of H2 for [Hg(HAPO)Cl2] (1), [Pd(HAPO)Cl2] (2), [Hg(APO)2] (3), and [Pd(APO)2] (4), respectively. Thermodynamic calculations show that the storage type of hydrogen is the physico‐absorption type. The study shows that the central metal has an effect on the ability of the complex to store hydrogen, as the palladium complexes are more capable of storing hydrogen than their mercury counterparts. [ABSTRACT FROM AUTHOR]

A tetrahedral Hg(II) diethyl dithiocarbamate (Et2Dt) complex containing triphenylphosphine (PPh3) of the composition [HgCl(κ2‐Et2Dt)2(PPh3)] (1) is prepared. Furthermore, complex (1) is used as a synthone to prepare a novel series of complexes of the following composition [Hg(Et2Dt)L(PPh3)] {L = saccharinate (2), thiosaccharinate (3), benzisothiazolinate (4), benzothiozole‐2‐thiolate (5), and benzooxazole‐2‐thiolate (6) anions}. The resulted complexes (1)–(6) are characterized by elemental analysis, molar conductivity, powder X‐ray diffraction, fourier transform Infrared, and NMR (1H and 31P) spectroscopic techniques. The Et2Dt ligand is coordinated as bidentate chelate through the sulfur atoms, whereas the L ligands are bonded as monodentate ligands to afford a tetrahedral geometry around the Hg(II) ion. Nitrogen adsorption–desorption isotherm for two of as‐prepared complexes (2) and (3) are measured first to get their Brunauer–Emmett–Teller surface area. Moreover, the mentioned two complexes are evaluated for their ability to store hydrogen gas at 77 K. However, the results of the hydrogen storage tests proved that the selected complexes are all capable of storing hydrogen, but in varying degrees, where complex (2) exhibited a storage capacity of 4.22 wt% under 88 bar. [ABSTRACT FROM AUTHOR]