Crystal Structure, Photophysical Properties and Antibacterial Activity of a Cd(II) Complex with Trans-2,3,4-Trimethoxycinnamic Acid and 4,4′-Bipyridine Ligands

A new coordination polymer {[Cd(C₁₂H₁₃O₅)₂(4,4'-bpy)(H₂O)₂]}_n (<b>Cd-Tmca-bpy</b>) was constructed with trans-2,3,4-Trimethoxycinnamic acid (HTmca) and 4,4'-Bipyridine (4,4'-bpy) ligands. This complex was structurally characterized on the basis of elemental analysis, infrared (IR) spectroscopy, powder X-ray diffraction and thermogravimetric analyses. X-ray crystallography revealed that the complex was monoclinic, space group C2/c. The Cd(II) ion in the complex was six coordinated, adopting an octahedron geometry. The neighboring Cd(II) ions linked linear ligand 4,4'-bpy molecules to form an infinite 1D chain. The 1D chain was further interlinked by O-H···O and C-H···O hydrogen bonds, resulting in a 3-D supramolecular framework. Meanwhile, the photoluminescence spectrum of the Cd(II) complex at room temperature exhibited an emission maximum at 475 nm. Using the time-dependent density functional theory (TD-DFT) method, the electronic absorption spectra of the Cd(II) complex was predicted. A good agreement was achieved between the predicted spectra and the experimental data. Bioactivity studies showed that the complex exhibited significant inhibition halos against <i>Pseudomonas aeruginosa</i> (<i>P. aeruginosa</i>) and <i>Staphylococcus aureus</i> (<i>S. aureus</i>).