Syntheses, Structures, and Characteristics of Four New Metal–Organic Frameworks Based on Flexible Tetrapyridines and Aromatic Polycarboxylate Acids

Abstract

Solvothermal reactions of tetrakis(4-pyridyloxymethylene)methane (TPOM) with deprotonated isophthalic acid (1,3-H2bdc), 5-hydroxyisophthalic acid (5-OH-H2bdc), benzene-1,3,5-tricarboxylic acid (H3btc), and benzene-1,2,4,5-tetracarboxylic acid (H4btc) in the presence of zinc and cobalt salts produce four new complexes, namely, {[Co2(TPOM)(bdc)2(H2O)2]·(H2O)3}n (1), {[Zn2(TPOM)(5-OH-bdc)2]·(DMF)(H2O)2}n (2), {[Co3(TPOM)(btc)2(H2O)]·(H2O)4}n (3), and {[Zn2(TPOM)(btc)2]n (4). Complexes 1 and 2 possess similar 2-fold interpenetrating three-dimensional (3D) framework with bbf topology, but 1 crystallizes in an achiral space group, and 2 crystallizes in chiral space group and displays ferroelectric behavior. Complex 3 reveals a 3D framework with biunclear Co clusters, which displays weak antiferromagnetic character. In complex 4, only H4btc links Zn(II) to generate a 3D porous framework, with TPOM occupying the void space as countercation and template. In addition, photochemical and ferroelectric properties of t...