Synthesis, structure, and fluorescence of two cadmium(II)-citrate coordination polymers with different coordination architectures

Two novel Cd(II)-citrate complexes were obtained with different metal/ligand ratios through hydrothermal method. Their structures were determined by single-crystal X-ray diffraction analysis. Although their topological structures are both 2-D layer network assemblies, both central Cd(II) ions and Hcit^3? ligands display completely different coordination modes. In polymeric complex 1, Hcit^3? serves as a μ₁₀-bridged and central Cd(II) ions adopt 6- and 8-coordinated configurations. In contrast, a μ₉-bridged and 6- and 7-coordinated environments between Cd(II) and Hcit^3? are established in the polymeric complex 2. Two Complexes remain stable up to approximately 300 °C. The complex 1 exhibits strong fluorescent emission band at 450 nm (λ=346 nm) as well as complex 2 exhibits strong fluorescent emission band at 430 (λ=346 nm).