Synthesis, crystal structures and antimicrobial activity of palladium metal complexes of sulfonyl hydrazone ligands

Abstract

Palladium complexes of sulfonyl hydrazone based ligands have been prepared by refluxing with the corresponding ligands and Pd(II) salt in 2:1 ratio. The compounds have been characterized by FT-IR and UV-Vis spectroscopic methods. The crystal structure of the prepared palladium complexes has been determined by single-crystal X-ray crystallographic technique. Crystal data for C₄₀H₅₀N₄O₆PdS₂ (PMHT-Pd(II) complex): triclinic, space group P-1 (no. 2), a = 7.1561(6) Å, b = 12.1300(11) Å, c = 12.6117(17) Å, α = 63.498(11)°, β = 86.694(9)°, γ = 81.451(7)° and Z = 1. The final R₁ was 0.0699 (I > 2σ(I)) and wR₂ was 0.1834 (all data). Crystal data for C₃₆H₄₂N₄O₆PdS₂ (PTHC-Pd(II) complex): monoclinic, space group P2₁/n (no. 14), a = 8.6726(2) Å, b = 20.8824(4) Å, c = 10.3351(2) Å, β = 104.429(2)° and Z = 2. The final R₁ was 0.0344 (I > 2σ(I)) and wR₂ was 0.0840 (all data). Crystal data for C₃₆H₄₂N₄O₆PdS₂ (PTHT-Pd(II) complex): monoclinic, space group P2₁/n (no. 14), a = 9.7658(2) Å, b = 10.0488(3) Å, c = 18.7714(4) Å, β = 99.602(2)° and Z = 2. The final R₁ was 0.0334 (I > 2σ(I)) and wR₂ was 0.0832 (all data). Crystal data for C₄₀H₅₀N₄O₆PdS₂ (PMHC-Pd(II) complex): triclinic, space group P-1 (no. 2), a = 10.2070(9) Å, b = 12.1841(13) Å, c = 16.8879(19) Å, α = 109.005(6)°, β = 90.061(5)°, γ = 99.032(5)° and Z = 2. The final R₁ was 0.0822 (I > 2σ(I)) and wR₂ was 0.2293 (all data). The single-crystal structure data showed a good agreement with the experimental results. The synthesized complexes were screened for their in vitro antibacterial activity against one Gram-negative (Escherichia coli) and two Gram-positive (Bacillus subtilis and Staphylococcus aureus) bacterial strains and for in vitro antifungal activity against Aspergillus niger, Aspergillus flavus and Aspergillus fumigatus. The PTHC-Pd(II) complex possesses the nearby significant antifungal activity analogous to the standard drug fluconazole against selected fungal strains Aspergillus niger, Aspergillus Flavus and Aspergillus fumigatus as well as the same complex showed the antibacterial activity for Staphylococcus aureus as comparable to standard ofloxacin drug.