5-chloro-3-(2-(2,4-dinitrophenyl) hydrazono)indolin-2-one: synthesis, characterization, biochemical and computational screening against SARS-CoV-2.

Chemical prototypes with broad-spectrum antiviral activity are important toward developing new therapies that can act on both existing and emerging viruses. Binding of the SARS-CoV-2 spike protein to the host angiotensin-converting enzyme 2 (ACE2) receptor is required for cellular entry of SARS-CoV-2. Toward identifying new chemical leads that can disrupt this interaction, including in the presence of SARS-CoV-2 adaptive mutations found in variants like omicron that can circumvent vaccine, immune, and therapeutic antibody responses, we synthesized 5-chloro-3-(2-(2,4-dinitrophenyl)hydrazono)indolin-2-one (H2L) from the condensation reaction of 5-chloroisatin and 2,4-dinitrophenylhydrazine in good yield. H2L was characterised by elemental and spectral (IR, electronic, Mass) analyses. The NMR spectrum of H2L indicated a keto-enol tautomerism, with the keto form being more abundant in solution. H2L was found to selectively interfere with binding of the SARS-CoV-2 spike receptor-binding domain (RBD) to the host angiotensin-converting enzyme 2 receptor with a 50% inhibitory concentration (IC50) of 0.26 µM, compared to an unrelated PD-1/PD-L1 ligand-receptor-binding pair with an IC50 of 2.06 µM in vitro (Selectivity index = 7.9). Molecular docking studies revealed that the synthesized ligand preferentially binds within the ACE2 receptor-binding site in a region distinct from where spike mutations in SARS-CoV-2 variants occur. Consistent with these models, H2L was able to disrupt ACE2 interactions with the RBDs from beta, delta, lambda, and omicron variants with similar activities. These studies indicate that H2L-derived compounds are potential inhibitors of multiple SARS-CoV-2 variants, including those capable of circumventing vaccine and immune responses. Supplementary Information: The online version contains supplementary material available at 10.1007/s11696-023-03274-5.

A homochiral coordination polymer of cobalt(II) and L-serine.

A one-dimensional chiral cobalt(II) coordination polymer, namely, catena-poly[[[(S)-2-amino-3-hydroxypropanoato-κ2N,O1]cobalt(II)]-µ-(S)-2-amino-3-hydroxypropanoato-κ4O1,O3:N,O1'], [Co(C3H6NO3)2]n or Δ-[Co(L-Ser-κ2N,O)2]n (L-Ser = L-serine) (1), has been synthesized and characterized using elemental and thermal analyses, IR spectroscopy and single-crystal and powder X-ray diffraction techniques. The asymmetric unit of 1 consists of two serine anions which are coordinated to a Co2+ ion to give three chelate rings. These extend the structure into a helical chain with pendant chelate rings which participate in interchain hydrogen bonding. The ability of 1 to undergo transmetallation was evaluated. Among a range of divalent metal ions, only copper(II) partially replaced cobalt(II).

Synthesis, mol-ecular and crystal structure of 1-(1,2-di-hydro-phthalazin-1-yl-idene)-2-[1-(thio-phen-2-yl)ethyl-idene]hydrazine.

The title compound, C14H12N4S, was synthesized by the condensation reaction of hydralazine and 2-acetyl-thio-phene and during the reaction, a proton transfer from the imino nitro-gen atom to one of the endocylic nitro-gen atoms occurred. The compound crystallizes in the monoclinic crystal system with two independent mol-ecules (mol-ecules 1 and 2) in the asymmetric unit. In each mol-ecule, there is a slight difference in the orientation of the thio-phene ring with respect to phthalazine ring system, mol-ecule 1 showing a dihedral angle of 42.51 (1)° compared to 8.48 (1)° in mol-ecule 2. This implies an r.m.s deviation of 0.428 (1) Šbetween the two mol-ecules for the 19 non-H atoms. The two independent mol-ecules are connected via two N-H⋯N hydrogen bonds, forming dimers which inter-act by two bifurcated π-π stacking inter-actions to build tetra-meric motifs. The latter are packed in the ac plane via weak C-H⋯π inter-actions and along the b axis via C-H ⋯N and C-H⋯π inter-actions. This results a three-dimensional architecture with a tilted herringbone packing mode.

Oligodentate P,N ligands: N,N,N',N'-tetrakis(diphenylphosphanyl)-1,3-diaminobenzene complexes of rhodium, nickel and palladium.

The oligodentate P,N ligand N,N,N',N'-tetrakis(diphenylphosphanyl)-1,3-diaminobenzene reacts with two equivalents of [{Rh(mu-Cl)(COD)}(2)], [NiBr(2)(DME)] or [PdCl(2)(NCMe)(2)](COD = 1,5-cyclooctadiene, DME = dimethoxyethane) in dichloromethane to give the tetranuclear complex [1,3-{cis-Rh(COD)(mu-Cl)(2)Rh(PPh(2))(2)N}(2)C(6)H(4)](1) or the dinuclear complexes [1,3-{cis-NiBr(2)(PPh(2))(2)N}(2)C(6)H(4)](2) and [1,3-{cis-PdCl(2)(PPh(2))(2)N}(2)C(6)H(4)](3), respectively. Compounds 1-3 were characterised by NMR ((1)H, (13)C, (31)P) and IR spectroscopy. The molecular structure of 2 and 3 shows the formation of a bis-chelate complex with M-P-N-P four-membered rings (M = Pd, Ni). An N,N,N',N'-tetrakis(diphenylphosphanyl)-1,3-diaminobenzene/Pd(OAc)(2) mixture was used for the copolymerisation of carbon monoxide with ethene or ethylidenenorbornene. Compound 1 was employed as catalyst in the hydrogenation of styrene.