A series of metal–organic frameworks constructed by a rigid-flexible 5-(bis(4-carboxybenzyl)amino)isophthalic acid: syntheses, crystal structures and physical properties

Abstract

Four new metal–organic frameworks (MOFs), namely, [Zn₂L]_n (1), [Mn(H₂L)(H₂O)]_n (2), [Cd(H₂L)(H₂O)₂]_n·nH₂O (3) and [Pb₂L(H₂O)]_n·3nH₂O·nDMF (4), have been prepared by using a tetracarboxylic acid ligand H₄L (H₄L = 5-(bis(4-carboxybenzyl)amino)isophthalic acid) under hydrothermal conditions and structurally characterized by elemental analysis, IR spectroscopy, single-crystal X-ray diffraction analysis and powder X-ray diffraction. Structural analyses revealed that 1, 2 and 4 exhibit three-dimensional network structures. The structure of 1 can be symbolized as a 2-nodal 6-connected net with a (4¹¹·6⁴)(4⁷·6⁸) topology. The framework of 2 can be considered as a 4-connected net with a (6²·8⁴)(6³·8³) topology. The structure of 4 can be regarded as a 5-connected net with a 4³·6⁶·8 topology. In contrast, 3 exhibits a 2D structure with a 3,3-connencted (6³)₂ topology. These MOFs exhibit excellent photocatalytic activities for dye degradation under visible light irradiation. Furthermore, 2 displays weak antiferromagnetic interaction at low temperature.