A Water-Rich Cobalt(II) Compound: Hydrothermal Synthesis, Spectroscopic, Thermal, Crystal Structure Characterization and Antimicrobial Properties

A water-rich mononuclear Co(II) compound, tris-(1,10-phenanthroline) cobalt(II) 1,4-phenylenediacrylate tetradecahydrate, [Co(phen)(3)](ppda) . 14H(2)O (1) (where phen is 1,10-phenanthroline; ppda is p-phenylenediacrylate) was prepared and characterized by elemental analyses, IR, Raman, UV-Vis, fluorescence spectra, magnetic studies, cyclic voltammetry, single crystal X-ray diffractometry and TG-DTA. The Co(II) ion in 1 is high spin (S=3/2) with mu(B)= similar to 3.98 B.M. and exhibits a reversible one electron Co-II/Co-III redox behavior. 1 crystallizes in a monoclinic centrosymmetric C2/c space group with unit cell parameters; a=23.1019(13), b=12.1077(5) and c=19.7428(1) angstrom; beta=111.410(2)degrees. The Co(II) ion is coordinated to three phen ligands to form [Co(phen)(3)](2+) cation. The (ppda)(2-) dianion and fourteen water molecules form a heterocyclic water cluster through O-H...O (ppda)(2-) and O-H...O (H2O) interactions while phen ligands on adjacent cations are stacked via pi-pi interactions. On heating compound 1 loses its fourteen water molecules upto 132 degrees C. 1 is a potent inhibitor for Gram Negative E. coli as compared to Gram Positive S. aureus.