Self-assembly of a series of metal–organic frameworks with semi-rigid multicarboxylate 3,4-bis(carboxymethoxy)benzoic acid ligands

Abstract

Seven new metal–organic frameworks based on 3,4-bis(carboxymethoxy)benzoic acid (H3bcba), 3,5-bis(4-pyridyl)-1,2,4-triazolyl (Hbpt) or 4,4′-bipyridyl (4,4′-bipy), named [Sr3(bcba)2(H2O)3]n (1), [Sr(Hbcba)(H2O)3]n (2), [Zn(Hbcba)(H2O)2]n (3), [Zn3(bcba)2(Hbpt)2(H2O)2]n (4), [Zn3(bcba)2(4,4′-bipy)2]n·nH2O (5), [Eu(bcba)(H2O)]n·nH2O (6) and [Nd(bcba)(H2O)]n·nH2O (7), have been successfully synthesized via hydrothermal reaction. Single crystal X-ray diffraction reveals that complexes 1, 3, 4 have one-dimensional (1D) zigzag chains, while the rest are composed of 1D double chains. The 3D network in complex 2 and 3 is formed by hydrogen bonds. Complex 4 constitutes a (3,3,4)-connected network and complex 5 constitutes a (4,5,6)-connected network. Complex 6 and 7 are isomorphous. In addition, the thermogravimetric analyses (TGA) for complexes 1–6 are discussed, and the luminescent properties of complex 3–6 have been also investigated.