Amide functionalized metal–organic frameworks for diastereoselective nitroaldol (Henry) reaction in aqueous medium

Abstract

The two new metal–organic frameworks (MOFs) of zinc(II) and copper(II) [Zn₂L₂(1,4-BDC)]_n·2n(DMF) (1) and [Cu(L)₂]_n·4n(DMF)·n(H₂O) (2) (L = 4-(pyridin-4-ylcarbamoyl)benzoate; BDC = benzenedicarboxylate), respectively, have been synthesized from a pyridyl amide functionalized benzoic acid (HL). They were characterized by elemental, FT-IR, thermogravimetric, powder X-ray and single crystal X-ray diffraction analyses. Single crystal X-ray crystallography reveals that 1 and 2 exhibit 2D and 3D polymeric architectures, respectively. Topological analysis illustrates a 6-connected pcu alpha-Po primitive cubic topology for 1 and an 8-connected body centred cubic (bcu) topology for 2. Both 1 and 2 act as heterogeneous catalysts for the nitroaldol reaction in aqueous medium, with a high yield and moderate to good diastereoselectivities under ambient conditions. They can be recycled and reused without any significant loss of the catalytic efficiency.