A novel adenine-based zinc(II) metal-organic framework featuring the Lewis basic sites for heterogeneous catalysis

Metal-organic frameworks (MOFs), as a new sort of crystalline materials, have attracted lots of interest in many applications during the past decades. Recently, many efforts have been focused on the development of MOFs as heterogeneous catalysis. In this communication, we selected adenine (ad) and tetracarboxylic acid, namely 5,5'-(1,3,6,8-tetraoxobenzo[Imn] Li et al. (1999), He et al. (2016) phenanthroline-2,7-diyl)bis-1,3-benzenedicarboxylic acid (H4L), as organic linkers to assemble with Zn(II) ions to construct a novel adenine-based porous MOF. There are three different inorganic clusters in the framework, including ZnO2N2, Zn2O2N6, and ZnO5N clusters. Interesting, the resultant porous MOF, namely [H2N(CH3)(2)]center dot[Zn-4(L)(1.5)(ad)(3)(H2O)(2)]center dot 4DMF, retains free amino groups in the framework, which can be served as Lewis basic sites to catalyse Knoevenagel condensation reaction. The catalytic study exhibits that the as-synthesized MOF with free amino groups can be used as heterogeneous catalysis with remarkable catalytic efforts and good recycle. (C) 2016 Published by Elsevier B.V.