Synthesis, structure and Hirshfeld analysis of the potent antimicrobial [Ag(4-bromopyrazole)2ClO4] complex

Abstract

The synthesis of a new silver(I) complex, [Ag(4Brpyz)2ClO4], (where 4Brpyz = 4-bromopyrazole) has been described. Its structural aspects were identified using elemental analysis, IR and 1H NMR spectroscopy, as well as single crystal X-ray diffraction. The crystallographic analysis revealed that the complex crystallizes in the centrosymmetric monoclinic space group P2(1)/c with one [Ag(4Brpyz)2ClO4] complex per asymmetric unit and Z = 4. The asymmetric unit is comprised of one Ag(I) ion, two units of 4Brpyz as an organic ligand and one disordered perchlorate anion (part A: 28.0% and part B: 72.0%). In part A, the structure of the complex is better described as one dimensional coordination polymer, [Ag(4Brpyz)2ClO4]n, where the perchlorate ions act as a connector between the [Ag(4Brpyz)2]+ units and are also included in NH…O hydrogen bonding interactions. On other hand, the major part (B) could be described as an ionic complex of the formula [Ag(4Brpyz)2]ClO4, where the free perchlorate anions are included in NH…O and CH…O hydrogen bonding interactions. The intermolecular interactions and the AgN/AgO coordinate bonds were analyzed using Hirshfeld and DFT analyses, respectively. The antimicrobial activity of the complex was compared with that of the free ligand and four commercially available antibiotics. The studied Ag(I) complex showed a lower MIC and hence better reactivity against bacteria and fungus compared to either the free ligand or any of the tested antibiotics.