Synthesis, crystal structures, and luminescent properties of Pb( II) and Sr( II) coordination polymers constructed by 5-methyl-1H-pyrazole-3-carboxylic acid

Two new coordination polymers, {[Pb(HMPCA)(2)]}(n) (1) and {[Sr(HMPCA)(2)(H2O)(2)]center dot H2O}(n) (2) (H(2)MPCA=5-methyl-1H-pyrazole-3-carboxylic acid), have been synthesized and characterized by elemental analysis, IR spectroscopy, X-ray diffraction, and thermogravimetric analysis. Compound 1 forms a one-dimensional (1-D) chain, and a two-dimensional (2-D) supramolecular framework is constructed by hydrogen bonding. The HMPCA(-) in 1 adopts two coordination modes, a N,O-chelate and a mu(3)-kappa N, O: kappa O, O': kappa O' mode. The structure of 2 is a 1-D Sr-O-Sr chain built up by two waters bridging a pair of distrontium [Sr(H2O)(HMPCA)(mu(2)-HMPCA)](2) units, and the chains are further extended into a 2-D supramolecular layer via hydrogen bonds. In addition to a N,O-chelate, the HMPCA(-) in 2 exhibit a third coordination mode, mu(2)-kappa N, O: kappa O. The thermal decomposition and luminescent properties of 1 and 2 in the solid state have also been investigated.