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

Abstract 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)]· solvents } n ( 2 ⊃ solvents ) and {[Zn 2 (bdc-(NO 2 ) 2 ) 2 (dabco)]· solvents } n ( 3 ⊃ 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 ⊃ solvents and 3 ⊃ 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)]·4H 2 O} n ( 2 ⊃4H 2 O) and {[Zn 2 (bdc-(NO 2 ) 2 ) 2 (dabco)]·6H 2 O} n ( 3 ⊃6H 2 O), showing the pore hydrophilicity enhancement caused by NO 2 group introduction.