Synthesis, Characterization, and Antimicrobial Activities of Two New Cu(II) Coordination Compounds of Piperazine-Based Proton Transfer Salts Containing 2,5-Pyridinedicarboxylate

Two new proton transfer salts containing 2,5-pyridinedicarboxylate (pdc2–) were synthesized with the piperazine derivatives {1-(2-hydroxyethyl)piperazine (pipOH) and piperazin-1-ylethanamine (pipNH2)}. Additionally, two new anionic coordination compounds were synthesized. The mononuclear complex, (H2pipOH)[Cu(pdc)2(H2O)]·H2O, was produced from salt (H2pipOH)(pdc) and two dimensional (2D) coordination polymer {(H2pipNH2)[Cu0.5(pdc)2Cu0.5(H2O)]·3H2O}n was generated from salt (H2pipNH2)(Hpdc)2. X-ray diffraction studies revealed that the mononuclear complex has a square pyramid geometry, while the polymeric complex contains two six-coordinated metal centers, and the geometry around both metals is octahedral. The charge of the complexes was balanced with piperazinium cations (H2pipOH)2+ and (H2pipNH2)2+. While elemental analysis, AAS, and spectral (UV-Vis, FTIR) methods were used to characterize salts and complexes, NMR spectroscopy was also performed on salts, and X-ray and magnetic susceptibility studies were performed on complexes. In addition, the antimicrobial activities of all compounds were tested against yeast and bacteria. Antimicrobial activity results were compared with vancomycin, levofloxacin, cefepime, chloramphenicol, fluconazole, and ketanazole.