Highly stable chiral cadmium 1,2,4-benzenetricarboxylate: Synthesis, structure, and NLO and fluorescence properties

Employing an unsymmetrical 1,2,4-benzenetricarboxylate as a bridging ligand, a new 3-D chiral cadmium coordination polymer [Cd-2(OH)(1,2,4-BTC)] (1,2,4-BTC = 1,2,4-benzenetricarboxylate) has been prepared under hydrothermal conditions and characterized by single crystal X-ray diffraction. This compound crystallizes in the orthorhombic space group P2(1)2(1)2(1), with cell parameters a = 6.900(2) angstrom, b = 7.404(3) angstrom, c = 19.116(5) angstrom, V = 976.5(5) angstrom(3), and Z = 4. Its structure contains 2-D Cd-O-Cd connectivity, which is further linked by the 1,2,4-BTC ligand into a 3-D supramolecular framework. The 1,2,4-BTC ligand shows a novel and unprecedented coordination mode: nine bonds to eight metals with each carboxylate as a tridentate group. The compound exhibits intense photoluminescence at room temperature and shows distinct NLO properties. On the basis of the results of TG/DTA analyses, the structure is thermally stable up to similar to 380 degrees C.