Synthesis, crystal structures and antitumor activities of copper(II) complexes with a 2-acetylpyrazine isonicotinoyl hydrazone ligand

Molecular docking, theoretical calculations, synthesis of Ru(III), Pd(II) and VO(II) complexes and activity determination as antibacterial and antioxidant

Molecular modeling calculations were used to validate 3D structures of new complexes of Ru(III), Pd(II) and VO(II) ions chelated with (E)-2-(phenylamino)-N-(pyridine-2-yl)methylene)acetohydrazide ligand. Furthermore, the calculations were used to estimate selected electronic chemical descriptors which are responsible for the biological activity. The first insight of the compound activity as antibacterial was evaluated by molecular docking analysis. The titled models showed stable binding towards lanosterol 14 alpha-demethylase (CYP51) enzyme of E. coli, indicating their inhibition effect toward bacterial growth. Structural study of the ligand and Ru(III), Pd(II) and VO(II) chelates was done using elemental analysis, FT-IR, 1H-NMR techniques. Furthermore, complexes were physically investigated based on magnetic moment, molar conductance, electronic spectroscopic and thermal analysis techniques. The antibacterial study of the synthesized compounds screened against both Gram-positive and Gram-negative bacteria revealed that these compounds display remarkable antibacterial activity and can be used as therapeutic drugs for pathogenic bacterial diseases. All complexes and ligand showed good scavenging activities which indicate a promising result for their applications as antioxidants.

Synthesis of Novel Tritopic Hydrazone Ligands: Spectroscopy, Biological Activity, DFT, and Molecular Docking Studies

Polytopic organic ligands with hydrazone moiety are at the forefront of new drug research among many others due to their unique and versatile functionality and ease of strategic ligand design. Quantum chemical calculations of these polyfunctional ligands can be carried out in silico to determine the thermodynamic parameters. In this study two new tritopic dihydrazide ligands, N’2, N’6-bis[(1E)-1-(thiophen-2-yl) ethylidene] pyridine-2,6-dicarbohydrazide (L1) and N’2, N’6-bis[(1E)-1-(1H-pyrrol-2-yl) ethylidene] pyridine-2,6-dicarbohydrazide (L2) were successfully prepared by the condensation reaction of pyridine-2,6-dicarboxylic hydrazide with 2-acetylthiophene and 2-acetylpyrrole. The FT-IR, 1H, and 13C NMR, as well as mass spectra of both L1 and L2, were recorded and analyzed. Quantum chemical calculations were performed at the DFT/B3LYP/cc-pvdz/6-311G+(d,p) level of theory to study the molecular geometry, vibrational frequencies, and thermodynamic properties including changes of ∆H, ∆S, and ∆G for both the ligands. The optimized vibrational frequency and (1H and 13C) NMR obtained by B3LYP/cc-pvdz/6-311G+(d,p) showed good agreement with experimental FT-IR and NMR data. Frontier molecular orbital (FMO) calculations were also conducted to find the HOMO, LUMO, and HOMO−LUMO gaps of the two synthesized compounds. To investigate the biological activities of the ligands, L1 and L2 were tested using in vitro bioassays against some Gram-negative and Gram-positive bacteria and fungus strains. In addition, molecular docking was used to study the molecular behavior of L1 and L2 against tyrosinase from Bacillus megaterium. The outcomes revealed that both L1 and L2 can suppress microbial growth of bacteria and fungi with variable potency. The antibacterial activity results demonstrated the compound L2 to be potentially effective against Bacillus megaterium with inhibition zones of 12 mm while the molecular docking study showed the binding energies for L1 and L2 to be −7.7 and −8.8 kcal mol−1, respectively, with tyrosinase from Bacillus megaterium.

Self-Assembly by Tridentate or Bidentate Ligand: Synthesis and Vapor Adsorption Properties of Cu(II), Zn(II), Hg(II) and Cd(II) Complexes Derived from a Bis(pyridylhydrazone) Compound

Four complexes, [Cu₄L₂(OCH₃)₂(CH₃OH)₂]·2H₂O (1), [Zn₂L₂Cl₄]·2H₂O·2CH₃OH (2), [Hg₂L₂Br₄]·4CH₃OH (3), and {[CdL₂Cl₂]·4H₂O·4CH₃OH}_n (4), have been synthesized and characterized from a bis(pyridylhydrazone) ligand (L) with copper(II), zinc(II), mercury(II) or cadmium(II), respectively. Complex 1 exists as a centrosymmetric tetranuclear dimer with L as deprotonated tridentate ligand. Complexes 2 and 3 exist as centrosymmetric metallamacrocycles with L as bidentate ligand. Complex 4 exists as a 1D looped-chain coordination polymer. The thermal stabilities and vapor adsorption properties of the four complexes were investigated as well.

The crystal structure of (2E,2′E)-,2,2′-bis[1-(2-pyrazinyl)ethylidene]carbonimidic dihydrazide, C13H15N9

C13H15N9, monoclinic, C2/c (no. 15), a = 22.827(5) Å, b = 7.8830(16) Å, c = 16.020(3) Å, β = 98.95(3)°, V = 2847.6(10) Å3, Z = 8, R gt(F) = 0.0416, wR ref(F 2) = 0.1331, T = 293(2) K.

Crystal structure of bis[3-methoxy-N-(1-(pyrazin-2-yl)ethylidene)benzohydrazonato-κ3 O,N,N′]nickel(II), C28H26N8O4Ni

C28H26N8O4Ni, orthorhombic, Pbcn (no. 60), a = 11.675(9) Å, b = 9.884(8) Å, c = 23.225(17) Å, V = 2680(4) Å3, Z = 4, R gt(F) = 0.0495, wR ref(F 2) = 0.1329, T = 296 K.

Crystal structure of bis [1-(phenylsulfonyl)-2-(1-(pyrazin-2-yl)ethylidene)hydrazin-1-ido-κ3 N,N′,O]cobalt(II), C24H22N8O4S2Co

C24H22N8O4S2Co, orthorhombic, Aba2 (no. 41), a = 12.043(5) Å, b = 21.723(9) Å, c = 9.961(4) Å, V = 2605.9(18) Å3, Z = 4, R gt(F) = 0.0366, wR ref(F 2) = 0.0764, T = 296(2) K.

Crystal structure of bis[2-(1-(3-ethylpyrazin-2-yl)ethylidene)-1-tosylhydrazin-1-ido-κ3-N,N′,O]copper(II), C30H34N8O4S2Cu

C30H34N8O4S2Cu, triclinic, P1̄ (no. 2), a = 12.9537(9) Å, b = 15.2802(10) Å, c = 17.1041(11) Å, α = 78.748(1)°, β = 79.684(1)°, γ = 79.270(1)°, V = 3226.4(4) Å3, Z = 4, R gt(F) = 0.0488, wR ref(F 2) = 0.1178, T = 296 K.

Crystal structure of bis(3-methyl-N-(1-(pyrazin-2-yl)ethylidene)benzohydrazonato-κ3 O,N,N′)nickel(II), C28H26N8O2Ni

C28H26N8O2Ni, orthorhombic, Aba2 (no. 41), a = 11.813(10) Å, b = 21.433(17) Å, c = 10.030(8) Å, V = 2539(4) Å3, Z = 4, R gt(F) = 0.0457, wR ref(F 2) = 0.0992, T = 296(2) K.

Crystal structure of bis(N-(1-(3-ethylpyrazin-2-yl)ethylidene)-3-hydroxy-2-naphthohydrazonato-κ3 N,N′,O)cobalt(II) — dimethylformamide (1/1), C41H41N9O5Co

C41H41N9O5Co, monoclinic, P21/n (no. 14), a = 10.666(4) Å, b = 18.538(6) Å, c = 19.585(7) Å, β = 104.036(7)°, V = 3757(2) Å3, Z = 4, R gt(F) = 0.0420, wR ref(F 2) = 0.1062, T = 296 K.

Crystal structure of bis-[N-(3-ethyl-1-pyrazin-2-yl-ethylidene)-3-bromo-benzoic acid-hydrazonato-κ3 O,N,N′)]-cadmium(II), C30H28N8O2Br2Cd

C30H28N8O2Br2Cd, triclinic, P1̄ (no. 2), a = 8.359(7) Å, b = 12.394(10) Å, c = 15.189(12) Å, α = 95.757(14)°, β = 90.593(16)°, γ = 106.961(15)°, V = 1496(2) Å3, Z = 2, R gt(F) = 0.0467, wR ref(F 2) = 0.0998, T = 296(2) K.

Crystal structure of bis-[N-(1-pyrazin-2-yl-ethylidene)-cyanoacetic acid-hydrazonato-κ3 O,N,N′)]-zinc(II), C18H16N10O2Zn

C18H16N10O2Zn, triclinic, P1̄ (no. 2), a = 10.218(7) Å, b = 10.490(7) Å, c = 11.101(8) Å, α = 79.590(11)°, β = 65.913(12)°, γ = 66.785(10)°, V = 998.0(12) Å3, Z = 2, R gt(F) = 0.0516, wR ref(F 2) = 0.1323, T = 293(2) K.

Crystal structure of (E)-2-cyano-N′-(1-(3-ethylpyrazin-2-yl)ethylidene)acetohydrazide, C11H3N5O

C11H3N5O, monoclinic, P21/c (no. 14), a = 15.727(4) Å, b = 5.0572(12) Å, c = 15.452(4) Å, β = 105.007(4)°, V = 1187.1(5) Å3, Z = 4, R gt(F) = 0.0408, wR ref(F 2) = 0.1123, T = 296 K.

Crystal structure of dichlorido-(N′-(1-(3-ethylpyrazin-2-yl)ethylidene)-4-methoxybenzohydrazide-κ3N,N′,O)cadmium(II), C16H18N4O2Cl2Cd

C16H18N4O2Cl2Cd, monoclinic, P21/n (no. 14), a = 9.833(2) Å, b = 17.404(4) Å, c = 11.694(3) Å, β = 112.901(3)°, V = 1843.5(8) Å3, Z = 4, Rgt(F) = 0.0280, wRref(F2) = 0.0728, T = 296(2) K.

Crystal structure of bis(3-chloro-N-(1-(pyrazin-2-yl)ethylidene)benzohydrazonato-k3 N,N′,O)nickel(II), C26H20N8O2Cl2Ni

C26H20N8O2Cl2Ni, orthorhombic, Pbcn (no. 60), a = 11.737(10) Å, b = 9.309(8) Å, c = 23.72(2) Å, V = 2592(4) Å3, Z = 4, R gt(F) = 0.0361, wR ref(F 2) = 0.0934, T = 296 K.

Synthesis, structure and bioactivity of Ni2+ and Cu2+ acylhydrazone complexes

Two acylhydrazone complexes, bis{6-methyl-N'-[1-(pyrazin-2-yl-κN¹)ethylidene]nicotinohydrazidato-κ²N',O}nickel(II), [Ni(C₁₃H₁₂N₅O)₂], (I), and di-μ-azido-κ⁴N¹:N¹-bis({6-methyl-N'-[1-(pyrazin-2-yl-κN¹)ethylidene]nicotinohydrazidato-κ²N',O}nickel(II)), [Cu₂(C₁₃H₁₂N₅O)₂(N₃)₂], (II), derived from 6-methyl-N'-[1-(pyrazin-2-yl)ethylidene]nicotinohydrazide (HL) and azide salts, have been synthesized. HL acts as an N,N',O-tridentate ligand in both complexes. Complex (I) crystallizes in the orthorhombic space group Pbcn and has a mononuclear structure, the azide co-ligand is not involved in crystallization and the Ni²⁺ centre lies in a distorted {N₄O₂} octahedral coordination environment. Complex (II) crystallizes in the triclinic space group P-1 and is a centrosymmetric binuclear complex with a crystallographically independent Cu²⁺ centre coordinating to three donor atoms from the deprotonated L^- ligand and to two N atoms belonging to two bridging azide anions. The two- and one-dimensional supramolecular structures are constructed by hydrogen-bonding interactions in (I) and (II), respectively. The in vitro urease inhibitory evaluation revealed that complex (II) showed a better inhibitory activity, with the IC₅₀ value being 1.32±0.4 µM. Both complexes can effectively bind to bovine serum albumin (BSA) by 1:1 binding, which was assessed via tryptophan emission-quenching measurements. The bioactivities of the two complexes towards jack bean urease were also studied by molecular docking. The effects of the metal ions and the coordination environments in the two complexes on in vitro urease inhibitory activity are preliminarily discussed.

Crystal structure of bis(N-(1-(pyrazin-2-yl)ethylidene)nicotinohydrazonato-κ3 N,N′,O)copper(II) C24H20N10O2Cu

C24H20N10O2Cu, orthorhombic, Aba2 (no. 41), a = 12.2281(16) Å, b = 19.176(3) Å, c = 9.8689(13) Å, V = 2314.1(5) Å3, Z = 4, R gt(F) = 0.0381, wR ref(F 2) = 0.0752, T = 296(3) K.

Crystal structure of bis(1-(phenylsulfonyl)-2-(1-(pyrazin-2-yl)ethylidene)hydrazin-1-ido-κ3 N,N′,O)nickel(II), C24H22N8O4S2Ni

C24H22N8O4S2Ni, orthorhombic, Aba2 (no. 41), a = 11.845(6) Å, b = 21.937(11) Å, c = 9.907(5) Å, V = 2574(2) Å3, Z = 4, R gt(F) = 0.0285, wR ref(F 2) = 0.0657, T = 296(2) K.

Crystal Structure of bis(1-(phenylsulfonyl)-2-(1-(pyrazin-2-yl)ethylidene)hydrazin-1-ido-κ3 N,N′,O)copper(II), C24H22N8O4S2Cu

C24H22N8O4S2Cu, orthorhombic, Aba2 (no. 41), a = 11.9395(18) Å, b = 21.813(3) Å, c = 10.1184(15) Å, V = 2635.2(7) Å3, Z = 4, R gt(F) = 0.0395, wR ref(F 2) = 0.0912, T = 296(2) K.