Syntheses, structures, and physical properties of three novel metal-organic frameworks constructed from aromatic polycarboxylate acids and flexible imidazole-based synthons

Three novel interesting coordination polymers, [Cd-3(SIP)(2)(bbi)(5)center dot 3H(2)O](n) (1), [Co-3(SIP)(2)(bix)(4)(2H(2)O)center dot 2H(2)O](n) (2), and [Cd(2,5-pydc)(2)(bix)(1.5)center dot H2O](n) (3) (SIP = 5-sulfoisophthalic acid monosodium salt; bbi = 1,1'-(1,4-butanediyl)bis(imidazole); bix = 1,4-bis(imidazol-1-ylmethyl)-benzene; 2,5-pydc = pyridine-2,5-dicarboxylic acid), have been isolated under hydrothermal conditions and structurally characterized. Polymer 1 has a 3D complicated framework comprised of an infinite 1D ladder-like chain and 2D layer structure. Polymer 2 features a 3D hydrated framework with uncoordinated water molecules trapped in the pores. Polymer 3 is a 2D infinite layer framework, which is further interconnected by hydrogen-bond interactions to lead to a 3D supramolecular architecture. Compounds 1 and 3 exhibit medium-strong fluorescent emissions in the solid state at room temperature and could be significant in the field of photoactive materials.