Syntheses, crystal structures, and water adsorption behaviors of jungle-gym-type porous coordination polymers containing nitro moieties

NO(2) containing dicarboxylate bridging ligands, nitroterephthalate (bdc-NO(2)) and 2,5-dinitroterephthalate (bdc-(NO(2))(2)), afford porous coordination polymers, [[Zn(2)(bdc-NO(2))(2)(dabco)] center dot solvents)(n) (2 superset of solvents) and ([Zn(2)(bdc-(NO(2))(2))(2)(dabco)] center dot solvents), (3 superset of solvents). Both compounds form jungle-gym-type regularities, where a 2D square grid composed of dinuclear Zn(2) units and dicarboxylate ligands is bridged by dabco molecules to extend the 2D layers into a 3D structure. In 2 superset of solvents and 3 superset of solvents, a rectangle pore surrounded by eight Zn(2) corners contains two and four NO(2) moieties, respectively. Thermal gravimetry (TG) and X-ray powder diffraction (XRPD) measurements reveal that both compounds maintain the frameworks regularities without guest molecules and with solvents such as MeOH, EtOH, i-PrOH, and Me(2)CO. Adsorption measurements reveal that dried 2 and 3 adsorb H(2)O molecules to be [[Zn(2)(bdc-NO(2))(2)(dabco)] center dot 4H(2)O}(n) (2 superset of 4H(2)O) and {[Zn(2)(bdc-(NO(2))(2))(2)(dabco)] center dot 6H(2)O}(n) (3 superset of 6H(2)O), showing the pore hydrophilicity enhancement caused by NO(2) group introduction. (C) 2009 Elsevier Inc. All rights reserved.