Synthesis, crystal structure and antimicrobial activities of two silver(I) complexes based on bis(pyrazole) and carboxylic acid co-ligands

Two dinuclear and centrosymmetric silver-containing complexes, namely [Ag₂(3,5-dmpz)₂(3,5-dmpz methanol)₂(tbtc)] (1) and [Ag₂(3,5-dmpz)₂(3,5-dmpz methanol)₂(dbtc)] (2) (3,5-dmpz: dimethylpyrazole; 3,5-dmpz methanol: 3,5-dimethylpyrazole methanol; H₂tbtc: tetrabromoterephthalic acid; H₂dbtc: 2,5-dibromoterephthalic acid), were prepared and characterized. X-ray crystallographic data of 1 and 2 revealed that trigonal environment of the Ag ions has a “compressed Y’s” geometry. The antimicrobial activity of 1 and 2 was tested against the Gram-positive, Gram-negative bacteria and fungus, displaying the better inhibiting activity than the individual AgNO₃ and 3,5-dimethylpyrazole, especially for Candida albicans (IC₅₀ 2.5 ± 0.1 mg mL ⁻¹ and 2.8 ± 0.2 mg mL⁻¹). The quantified IC₅₀ values displayed that complexes 1 and 2 were more effective against fungus than the Gram-negative bacteria and Gram-positive bacteria.