A 3D supramolecular assembly of Co(II) MOF constructed with 2,5-pyridinedicarboxylate strut and its catalytic activity towards synthesis of tetrahydrobiphenylene-1,3-dicarbonitriles

Abstract

A cobalt based MOF, [Co(2,5-Pydc)(H2O)2].H2O (CoPy) was hydrothermally synthesized by employing 2,5-Pyridinedicarboxylic acid (2,5-Pydc) as organic strut; and its characteristics were characterized by single crystal XRD, FT-IR, TGA and fluorescent measurements. The single crystal XRD studies reveals that the compound crystallized in orthorhombic crystal system of space group P212121 with lattice parameters a = 7.3253(1) Å b = 9.3906(1) Å c = 13.8054(2) Å. In CoPy, the central metal atom (Co2+) adopts a six coordination geometry by using the carboxylate oxygen atoms and nitrogen atom of pyridine ring of 2,5-Pydc. The compound is linked with 2,5-Pydc ligand in all three directions through hydrogen bonding and π-π stacking interactions, which further develops a supramolecular 3-dimensional assembled network. The CoPy exhibited impressive catalytic activity in the synthesis of seven tetrahydrobiphenylene-1,3-dicarbonitrile derivatives via an one-pot, three-component reaction between aromatic aldehyde, malononitrile and 3-methyl-cyclohexanon in ethanol giving excellent yields (91–96%) in 20-35 min reaction time. The Lewis acidic sites of CoPy, by Co2+ open metal sites probably ensure its catalytic performance. The eco-friendly protocol and recyclability of CoPy, with no noticeable leaching of metal ion, undoubtedly makes it an ideal catalyst.