Mixed Metal-Organic Framework as a Heterogeneous Catalyst

Abstract

The synthesis of a new mixed metal-organic framework (M′MOF) has been accomplished by the metalloligand approach. [NaCu(2,4-HPdc)(2,4-Pdc)] (2,4-H2Pdc = pyridine-2,4-dicarboxylic acid) has been obtained from the hydrothermal reaction of the metalloligand [Cu(2,4-HPdc)2(H2O)2] NaOH, and a transition metal salt. [NaCu(2,4-HPdc)(2,4-Pdc)] is isostructural to [CuMn(2,4-Pdc)2] and crystallizes in the triclinic space group P$\bar {1}$. The 3D structure is built up from [Cu(2,4-HPdc)2(H2O)2] metalloligands and [NaO6] octahedra in a pcu α-Po-like uninodal six-connected net. The compound is stable to 290 °C, and its crystal structure undergoes a 3 % volume expansion between room temperature and thermal decomposition. The unsaturated CuII centers at the surface act as a heterogeneous Lewis acid catalyst for the cyanosilylation of aldehydes and Knoevenagel C-C bond-forming reactions. The catalytic activity has been compared with those of other copper(II) porous metal-organic frameworks such as HKUST-1 and MOF-74.