An interpenetrating amine-functionalized metal–organic framework as an efficient and reusable catalyst for the selective synthesis of tetrahydro-chromenes

Abstract

The amine group of the 2-amino-1,4-benzenedicarboxylic acid (NH₂-BDC) ligand in a novel two-fold interpenetrated metal–organic framework, [Zn(NH₂-BDC)(4-bpdb)]·2DMF (TMU-17-NH₂) has been found to be a base catalyst active site. TMU-17-NH₂ consists of both NH₂-BDC and the N,N′-bipyridine-type rigid linkers (4-bpdb = 1,4-bis(4-pyridyl)-2,3-diaza-2,3-butadiene) with ZnN₂O₄ secondary building units (SBUs). The MOF was characterized by FT-IR spectroscopy, elemental analysis, powder X-ray diffraction, thermal gravimetric analysis and single-crystal X-ray diffraction. The amine-functionalized framework was used as an efficient heterogeneous base catalyst for the synthesis of tetrahydro-chromenes. Excellent conversions were obtained under mild conditions in the presence of 6 mol% catalyst. The TMU-17-NH₂ catalyst could be reused several times without significant degradation in catalytic activity.