Design and synthesis of a heteroatom-rich Ni-MOF with a rare bis(µ-aqua) core for polarity-mediated heterogeneous catalysis

Abstract

In this work, a new robust Ni-based metal-organic framework (MOF), Ni-MOF, has been synthesized using an oxygen-bearing tetrapodal pyridyl ligand, tetrakis(4-pyridyloxymethylene)methane (4-TPOM), and a polar angular dicarboxylate linker, dibenzothiophene-5,5′-dioxide-3,7-dicarboxylate (3,7-DBTDC 2-). Its single crystal X-ray structure reveals a two-dimensional (2D) framework featuring the bis(aqua)dinickel core with an sql topology and the presence of two dangling pyridyl groups. A synergistic effect of the catalytic properties of Ni centers and the polar functional groups in Ni-MOF for an effective interaction with the substrates facilitates the formation of various quinazolin-4(3H)one derivatives with only 2 mol % at 90 °C using tert-butyl hydroperoxide TBHP (70% in H2O) as oxidant for 6 h in a water/THF mixture (4:1, v/v). Its structural integrity was confirmed by the post-catalytic PXRD, XPS and FESEM analyses. Utilizing experimental and theoretical support (CBMC and QTAIM simulations), a clear mechanistic pathway is defined.