Syntheses and Structures of Four d¹⁰ Metal−Organic Frameworks Assembled with Aromatic Polycarboxylate and bix [bix = 1,4-Bis(imidazol-1-ylmethyl)benzene]

Abstract

Four novel interesting cadmium(II) or zinc(II) metal coordination polymers, [Cd2(2,3-pydc)2(bix)3·2H2O]n (1), [Cd2(μ2-OH2)(2,6-pydc)2(bix)]n (2), [Cd3(SIP)2(bix)4·8H2O]n (3), and [Zn2(SIP)(bix)3(OH)·2H2O]n (4) (bix = 1,4-bis(imidazol-1-ylmethyl)-benzene; 2,3-pydc = pyridine-2,3-dicarboxylic acid; 2,6-pydc = pyridine-2,6-dicarboxylic acid; SIP = 5-sulfoisophthalic acid monosodium salt), have been synthesized under hydrothermal conditions and structurally characterized. Polymer 1 features a 3D porous framework with uncoordinated water molecules trapped in the pores. Polymer 2 is a 2D infinite layer framework, and the resulting 2D structure is interconnected by hydrogen-bond interactions to lead to a 3D supramolecular architecture. Polymer 3 also possesses a 3D porous framework; the most prominent cavities are parallel to the a- and b- directions and are filled with free water molecules. Polymer 4 exhibits 4-fold interpenetration related by three different translation vectors. These four compounds exhibit strong fluorescent emissions in the solid state at room temperature and could be significant in the field of photoactive materials.