Calixarene-based polyoxometalate organic–inorganic hybrid and coordination polymer as heterogeneous catalysts for azide–alkyne cycloaddition and Knoevenagel condensation reaction†
Based on a neutral pyridyl-functional calixarene ligand (L = tetrakis [(3-pyridylmethyl)oxy]-p-tertbutylcalixarene), one polyoxometalate-based organic–inorganic hybrid [Cu2L(SiW12O40)0.5]·CH3CN·2H2O (1) and one coordination polymer [CdCl2L]·CH3CN (2) have been successfully synthesized under solvothermal conditions. 1 exhibits a distinctive layer attributed to the weak interactions among the positive Cu(I)–L chains and [SiW12O40]4 anions. 2 displays a chain model containing a Cd(II) dimer. Both 1 and 2 were investigated as heterogeneous catalysts. 1 is an excellent heterogeneous catalyst for the azide–alkyne cycloaddition (AAC) reaction and 2 exhibits highly efficient catalytic performance for the Knoevenagel condensation reaction. Both 1 and 2 were easily separated.