Synthesis and characterization of two new coordination supramolecular structures from a versatile unsymmetric 5-(4-pyridyl)-1,3,4-oxadiazole-2-thione (Hpot) ligand

摘要

Two new inorganic-organic coordination networks based on a versatile and unsymmetric building block 5-(4-pyridyl)-1,3,4-oxadiazole-2-thione (Hpot) and inorganic Co-II and Cd-II salts have been synthesized in mixed solvent media and structurally characterized by single-crystal X-ray diffraction analysis. Crystal Hpot (1) was obtained from methanol solution. Reaction of Co(NO3)(2)center dot 6H(2)O with Hpot afforded a neutral two-dimensional (2-D) porous coordination polymer {[Co(pot)(2)] center dot 6H(2)O}(n) (2) with a (4,4) network, which shows a 3-D supramolecular network through O-H center dot center dot center dot O weak interactions. While substituting the transition metal ions used in 2 with Cd(NO3)(2)center dot 6H(2)O, a neutral 2-D coordination polymer [Cd-2(pot)(4)](n) (3) with a (6,3) network which further extended to a 3-D supramolecular structure through versatile hydrogen bonds C-H center dot center dot center dot X (X = O, N and S) was obtained. It is remarkable that the building block "pot" anion exhibits versatile coordination modes in complexes 2 and 3. These results indicate that the versatile nature of this rigid unsymmetric ligand, together with the coordination preferences of the metal centers, plays a critical role in construction of novel coordination polymers. The properties of gas absorption, magnetism and luminescence of 2 and 3 have been investigated and discussed in detail. (c) 2006 Elsevier Ltd. All rights reserved.