Syntheses, structures, and properties of copper(II), cobalt(II), and cadmium(II) complexes with flexible multicarboxylate ligand

摘要

Three new coordination polymers, namely, [CuL_(0.5)] (1), [Co(H_2L)(H_2O)_2][H_2O] (2), and [(CdCl)_(0.5)Cd_(0.25)(H_2L)_(0.5)] (3) were synthesized under hydrothermal conditions from the corresponding Cu ~(II), Co~(II), and CdII salts with a multidentate ligand of 2,2′,2′′,2′′′-[2,3,5,6- tetramethyl-1,4-phenylenebis(methylenenitrilo)]tetraacetic acid (H _4L). The complexes were characterized by single-crystal X-ray diffraction, IR, thermogravimetric, and elemental analyses. Complex 1 crystallizes in the orthorhombic space group Pbca and has a three-dimensional architecture with infinite two-dimensional networks linked together by weak Cu-O interactions. Complex 2 crystallizes in the monoclinic space group P2(1) and displays a 2D network. Complex 3 crystallizes in the tetragonal space group P4(2)cm and exhibits an infinite 3D architecture that has unusual [Cd _2(CO_2)_4Cl_2] dinuclear paddle-wheel units and [Cd(CO_2)_4] dodecahedron units. The results showed that the coordination arrangement of central metal atoms and the conformation and coordination mode of organic ligands play an important role in determining the structure of the complexes. The luminescence property of complex 3 was studied in the solid state at room temperature.