Synthesis, crystal structure, spectroscopic properties, and antimicrobial studies of a zinc(II) complex of p-coumaric acid

The synthesis of the zinc(II) complex of p-coumaric acid is described. The chemical formula of the complex as obtained from the single-crystal X-ray analysis is [Zn4(C9H7O3)8(H2O)6]center dot 4(H2O). The compound crystallizes in the triclinic space group P-1 with one molecule in the unit cell. There are two crystallographically independent Zn(II) cations in the structure. Zn1 is six-coordinate to three different carboxylate oxygens and three waters in a distorted octahedral geometry, whereas Zn2 ions are connected to four oxygens from four p-coumarate anions resulting in tetrahedral geometry. Adjacent cations are connected by bridging carboxylates to form centrosymmetric tetranuclear aggregates. Adjacent molecules are connected by a net of strong OHO hydrogen bonds into a 3D supramolecular framework with 1D open channels filled with water molecules. The zinc complex was characterized by infrared spectroscopy and 1H and 13C NMR spectra. The antimicrobial activities of zinc p-coumarate toward Bacillus subtilis, Candida albicans, Pseudomonas aeruginosa, Proteus vulgaris, and Staphylococcus aureus were tested.