Hydrothermal synthesis, crystal structure and heterogeneous catalytic activity of a novel inorganic-organic hybrid complex, possessing infinite La-O-La linkages

In this paper, a novel lanthanum coordination polymer formulated as {[La-2(Hpdc)(3)(H2O)(4)]center dot 2H(2)O}(n) (1, H(3)pdc = 3,5-pyrazoledicarboxylic acid) has been synthesized by the reaction of H(3)pdc with chloride salt of La(III) under hydrothermal conditions and characterized by elemental analysis, FT-IR, TGA and single-crystal X-ray diffraction. The complex crystallized in the monoclinic system Cc space group. The single-crystal X-ray structural analysis revealed that central metal La atoms are nine-coordinate and linked by bridging mu(2)-O-COO(-) groups to form [La(1)-(mu(2)-O-COO(-))(2)-La(2)](n) inorganic-organic chains that produce a supramolecular polymeric framework structure. The three-dimensional structure of 1 is accompanied by non-coordinating water molecules. Thermal behavior and catalytic performance of 1 have also been studied. The complex 1 showed 100% selectivity and a conversion rate of 24% on the oxidation of thymol (T) to thymoquinone (TQ). (C) 2013 Elsevier B. V. All rights reserved.