Synthesis, structure, and luminescent properties of 2 novel 5-chlorhydroxybenzoate-imidazole metal-organic complexes

Two novel Zn and Cu complexes with 5-chlorhydroxybenzoate and imidazole ligands, C41H36Zn2N8O13Cl4 (1) and C26H22Cl2Cu2N8O6 (2), were prepared by slow evaporation method. Single crystal X-ray diffraction analysis was used to determine their structures. The purity of the complexes was confirmed by powder X-ray diffraction analysis. In 1 the Zn2+ cation is tetracoordinated with 2 nitrogen atoms from 2 imidazoles and 2 oxygen atoms from the 2 carboxyl groups in 5-chlorhydroxybenzoate. In 2 the coordination polyhedrons of Cu2+ center can be described as distorted square pyramidal geometry sharing common edges, with an oxygen atom on the top of the pyramid. The hydrogen bonds and p-p interactions between the 2 ligands contribute to the presence of the infinite one-dimensional chain in the structure. Furthermore, solid-state fluorescence spectra indicate that both complexes show violet-blue fluorescence and can be potentially used as violet-blue fluorescence materials.