A three-dimensional cadmium coordination polymer based on 1,4-bis(1,2,4-triazol-1-yl)but-2-ene and benzene-1,3,5-tricarboxylic acid.

The Cd three-dimensional coordination poly[[[μ-1,4-bis(1,2,4-triazol-1-yl)but-2-ene]bis(μ-5-carboxybenzene-1,3-dicarboxylato)dicadmium(II)] dihydrate], {[Cd(CHO)(CHN)]·2HO}, (I), has been synthesized by the hydrothermal reaction of Cd(NO)·4HO, benzene-1,3,5-tricarboxylic acid (1,3,5-HBTC) and 1,4-bis(1,2,4-triazol-1-yl)but-2-ene (1,4-btbe). The IR spectrum suggests the presence of protonated carboxylic acid, deprotonated carboxylate and triazolyl groups. The purity of the bulk sample was confirmed by elemental analysis and X-ray powder diffraction. Single-crystal X-ray diffraction analysis reveals that the Cd ions adopt a five-coordinated distorted trigonal-bipyramidal geometry, coordinated by three O atoms from three different 1,3,5-HBTC ligands and two N atoms from two different 1,4-btbe ligands; the latter are situated on centres of inversion. The Cd centres are bridged by 1,3,5-HBTC and 1,4-btbe ligands into an overall three-dimensional framework. When the Cd centres and the tetradentate 1,4-btbe ligands are regarded as nodes, the three-dimensional topology can be simplified as a binodal 4,6-connected network. Thermogravimetric analysis confirms the presence of lattice water in (I). Photoluminescence studies imply that the emission of (I) may be ascribed to intraligand fluorescence.