Structural Regulation of Two Polyoxometalate-Based Metal-Organic Frameworks for the Heterogeneous Catalysis of Quinazolinones.

Two dimeric {ε- Zn 4 PMo 12 }-based metal-organic frameworks (MOFs), [ε-PMo 8 V Mo 4 VI O 34 (OH) 6 Zn 4 ][LO] ( SDUT-21 , LO = [5-((4'-carboxybenzyl)oxy)isophthalic acid]) and [TBA] 3 [ε-PMo 8 V Mo 4 VI O 37 (OH) 3 Zn 4 ][LN] ( SDUT-22 , TBA + = tetrabutylammonium ion, LN = [5-((4-carboxybenzyl)imino)isophthalic acid]), combining the advantages of polyoxometalates (POMs) and MOFs, were synthesized by the one-pot assembly strategy. The dimeric {ε- Zn 4 PMo 12 } units act as nodes that are linked by the flexible ligands and extended into two- or three-dimensional frameworks. The cyclic voltammetry and proton conductivity measurements of SDUT-21 and SDUT-22 were performed and indicated the high electron and proton transfer abilities. These materials also e xhibited the catalytic performance for the synthesis of quinazolinones in the heterogeneous state, and the different binding capacities toward the substrates caused the catalytic activity of SDUT-21 to be higher than that of SDUT-22 under the same conditions. In addition, the used catalysts could be readily recovered for five successive cycles and maintained high catalytic efficiency.