Luminescent cadmium dimethylsuccinate and dimethylglutarate coordination polymers self-assembled in the presence of flexible dipyridylamide ligands with capability for nitrobenzene detection

Abstract

Hydrothermal reaction of cadmium nitrate, a dimethyl-substituted aliphatic α,ω-carboxylic acid, and a flexible dipyridylamide ligand afforded four crystalline coordination polymers whose dimensionality and topology depended on the nitrogen donor disposition within the dipyridyl subunit and the length of the aliphatic chain subunit. These new crystalline phases were structurally characterized by single-crystal X-ray diffraction. {[Cd(dmg)(3-pmna)(H2O)]·H2O}n (1, dmg=2,2-dimethylglutarate, 3-pmna=3-pyridylmethylnicotinamide) manifests a simple (4,4) grid structure. {[Cd(dms)(3-pmna)(H2O)]·4.5H2O}n (2, dms=2,2-dimethylsuccinate) displays a 1D coordination polymer ladder motif with looped pairs of struts. {[Cd(dms)(4-pmina)]·2.5H2O}n (3, 4-pmina=4-pyridylmethylisonicotinamide) shows a 3,5-connected 2-fold interpenetrated binodal net with (426)(426583) topology, wherein the 4-pmina ligands serve as 3-connected nodes. Higher temperature synthetic regimes afforded {[Cd4(dms)4(H2O)4]·H2O}n (4) which manifests a 66 diamondoid topology based on [Cd4(dms)4(H2O)4]n subunits with embedded cuboid {Cd4O4} tetranuclear clusters. Thermal and luminescent properties of these new materials are also presented. The 3-D phase 3 showed potential as a detector for nitrobenzene.