Effect of heterocyclic nitrogen donor ligands on coordination behavior of weakly coordinating arylsulfonate: Synthesis, characterization and antimicrobial activities of [Cu(β-pic)4(2-Cl-5-nitrobenzenesulfonate)2](methanol) and [Cu(γ-pic)4(2-Cl-5 nitrobenz

• Effect of heterocyclic nitrogen donor ligands on coordination mode of arylsulfonate.
• X-ray structure delineates monodentate mode of coordination of arylsulfonate.
• EPR spectra revealed similarity of chromophore present CuN4O2 in both complexes.
• Significant antimicrobial activity of both complexes against Gram +ve bacteria.

Two new copper(II) complexes [Cu(β-pic)4(2-Cl-5-nitrobenzenesulfonate)2](CH3OH) (1) and [Cu(γ-pic)4(2-Cl-5-nitrobenzenesulfonate)2] (2) have been synthesized by reacting appropriate starting materials in methanol:water (v/v 4:1). Both newly synthesized complexes have been characterized on the basis of elemental analyses, spectroscopic techniques (FT-IR, UV–Vis, EPR) and single crystal X-ray structure determination (complex 1). The structural analysis of complex 1 revealed the existence of unusual coordination behavior of arylsulfonate towards copper(II) center in presence of heterocyclic N-donor ligands resulting in elongated octahedral geometry around the metal. The EPR spectroscopy of complexes 1 and 2 unambiguously proved a similar coordination of four picolines in Cu(II) xy plane. Antimicrobial studies of both the complexes 1 and 2 were performed against Gram positive, MRSA (Methicillin-Resistant Staphylococcus aureus) as well as Gram negative (Escherichia coli, Klebsiella pneumoniae) bacteria. The activity was investigated by using both Agar well diffusion as well as MIC assay. Both the complexes show significant bactericidal activity against all the pathogenic strains in comparison to ampicillin, a broad spectrum antibiotic against Gram positive and Gram negative bacteria.

Two new copper(II)complexes have been synthesized, [Cu(β-pic)4(2-Cl-5-nitrobenzenesulfonate)2](methanol), 1 and [Cu(γ-pic)4(2-Cl-5-nitrobenzenesulfonate)2], 2 and characterized by elemental analyses, UV–Vis, FT-IR, EPR and TGA analysis. Both the complexes when tested against different bacterial strains showed significant antibacterial activity as compared to standard broad spectrum ampicillin especially in case of Gram positive bacteria.Figure optionsDownload as PowerPoint slide