Synthesis, characterization, crystal structures and DFT studies of some new 1,2,4-triazole and triazolidin derivatives

Design and synthesis of methyl 2-{[4-phenyl-5-(pyridin-2-yl)-4H-1,2,4-triazol-3-yl]sulfanyl}acetate (phpy2NS) as a ligand for complexes of Group 12 elements: structural assessment and hydrogen-bonded supramolecular assembly analysis

The reaction of 2-cyanopyridine with N-phenylthiosemicarbazide afforded 2-[amino(pyridin-2-yl)methylidene]-N-phenylhydrazine-1-carbothioamide (Ham4ph) and crystals of 4-phenyl-5-(pyridin-2-yl)-2,4-dihydro-3H-1,2,4-triazole-3-thione (pyph3NS, 1, C₁₃H₁₀N₄S). Crystals of methyl 2-{[4-phenyl-5-(pyridin-2-yl)-4H-1,2,4-triazol-3-yl]sulfanyl}acetate (phpy2NS, 2, C₁₆H₁₄N₄O₂S), derived from 1, were obtained by the reaction of Ham4ph with chloroacetic acid, followed by the acid-catalyzed esterification of the carboxylic acid with methyl alcohol. Crystals of bis(methanol-κO)bis(methyl 2-{[4-phenyl-5-(pyridin-2-yl)-4H-1,2,4-triazol-3-yl-κ²N¹,N⁵]sulfanyl}acetato)zinc(II)/cadmium(II) hexabromidocadmate(II), [Zn_0.76Cd_0.24(C₁₆H₁₄N₄O₂S)₂(CH₃OH)₂][Cd₂Br₆] or [Zn_0.76Cd_0.24(phpy2NS)₂(MeOH)₂][Cd₂Br₆], 3, and dichlorido(methyl 2-{[4-phenyl-5-(pyridin-2-yl)-4H-1,2,4-triazol-3-yl-κ²N¹,N⁵]sulfanyl}acetato)mercury(II), [HgCl₂(C₁₆H₁₄N₄O₂S)] or [Hg(phpy2NS)Cl₂], 4, were synthesized using ligand 2 and CdBr₂ or HgCl₂, respectively. The molecular and supramolecular structures of the compounds were studied by X-ray diffractometry. The asymmetric unit of 3 is formed from CdBr₃ and M(phpy2NS)(MeOH) units, where the metal centre M has a 76% occupancy of Zn^II and 24% of Cd^II. The M²⁺ centre of the cation, located on a crystallographic inversion centre, is hexacoordinated and appears as a slightly distorted octahedral [MN₄O₂]²⁺ cation. The Cd centre of the anion is coordinated by two terminal bromide ligands and two bridging bromide ligands that generate [Cd₂Br₆]^2- cadmium-bromide clusters. These clusters display crystallographic inversion symmetry forming two edge-shared tetrahedra and serve as agents that direct the structure in the formation of supramolecular assemblies. In mononuclear complex 4, the coordination geometry around the Hg²⁺ ion is distorted tetrahedral and comprises two chloride ligands and two N-atom donors from the phpy2NS ligand, viz. one pyridine N atom and the other from triazole. In the crystal packing, all four compounds exhibit weak intermolecular interactions, which facilitate the formation of three-dimensional architectures. Along with the noncovalent interactions, the structural diversity in the complexes can be attributed to the metal centre and to the coordination geometry, as well as to its ionic or neutral character.

Evaluation of Novel N-(Dibenzylcarbamothioyl)benzamide Derivatives as Antibacterial Agents by Using DFT and Drug-Likeness Assessment

Isomers of monothioureas, 2a–2d, derived from the reaction of disubstituted benzoyl isothiocyanate and dibenzylamine were synthesised and characterised by using elementary analysis CHNS and IR, 1H NMR, and 13C NMR spectroscopies. The compounds were screened for their in vitro antibacterial activity by using selected Gram-positive bacteria, and moderate inhibition activity was displayed for compound 2b with the value of inhibition zone 11 ± 0.8 mm at a concentration of 50 mg/ml. The outcomes of Lipinski’s rule of five assessment appeared to be in agreement with all compounds as they adhered to most of the rules, in which they can be preliminarily classified as active drug-like. The frontier molecular orbitals (HOMO and LUMO) for halogen-substituted 3,4-dichloro (2a) and 3,4-difluoro (2b) were also determined by applying the computational method of density functional theory (DFT) to determine their relationship as a molecular descriptor in antibacterial activities. The value of LUMO energy for compound 2b (1.8229 eV) is lower than that of compound 2a (1.8492 eV) which indicates higher antibacterial activities.