Syntheses, structures and properties of cadmium benzenedicarboxylate metal–organic frameworks

Abstract

The products isolated from the reaction between Cd(NO3)2 x 4H2O and 1,4-benzenedicarboxylic acid (H2bdc) in DMF are very dependent on the conditions. At 115 degrees C, the reaction gives [Cd(bdc)(DMF)]infinity, which has a three-dimensional network structure, whereas at 95 degrees C, 1 is formed alongside [Cd3(bdc)3(DMF)4]infinity 2, which has a two-dimensional network structure. When the reaction is carried out under pressure, it yields [Cd3(bdc)3(DMF)4]infinity 3, which is a supramolecular isomer of 2. The structure of 3 differs from that of 2 regarding the way the Cd3(O2CR)6 units are interlinked to form layers. When the reaction was carried out in DMF that had undergone partial hydrolysis, the only isolated product was [(NMe2H2)2[Cd(bdc)2] x 2DMF]infinity 4. Compound 4 has a three-dimensional triply-interpenetrated diamondoid structure, with dimethylammonium cations and DMF molecules included within the pores. The reaction between Cd(NO3)2 x 4H2O and H2bdc in DEF gave [Cd(bdc)(DEF)]infinity 5, regardless of the solvent quality. Compound 5 has a three-dimensional network structure. The reaction of Cd(NO3)2 x 4H2O and 1,3-benzenedicarboxylic acid (H2mbdc) in DMF gave [Cd(mbdc)(DMF)]infinity 6 which has a bilayer structure. The thermal properties of the new materials have been investigated, and the coordinated DEF molecules from 5 can be removed on heating to 400 degrees C without any change in the powder X-ray diffraction pattern. The H2 sorption isotherm for the desolvated material shows marked hysteresis between adsorption and desorption, and less adsorption than predicted by simulations. Kinetic data indicate that the hysteresis is not due to mass transfer limitations, and the most likely explanation for this behaviour lies in partial collapse of the framework to an amorphous phase under the conditions of activation.

Ligand-tuned metal coordination polymers constructed by the linear Cd3(COO)6/8 clusters: Preparations, structures, topologies and gas adsorptive properties

“…Nevertheless, if the same reactants were heated to a slightly higher temperature (95°C) without Pz, 2 is the minor product alongside the [Cd(bdc)(DMF)]. Under the same procedure at higher temperature (115°C) and pressurized with 3 bar N 2 , the sole product [Cd 3 (1,4-bdc) 3 (DMF) 4 ], a topological supramolecular isomer (6 Â 3 net) of 2, had been yielded [48].…”

“…[48] or our previous paper [43], respectively, it is essential to give a briefly comparison hereinto. As shown in Fig.…”

“…Reaction of Cd(NO 3 ) 2 Á4H 2 O and 1,4-bdcH 2 with DEF as solvent obtained unique produce, [Cd 3 (bdc) 3 (DEF) 2 ] (bdc = benzene dicarboxylate and DEF = N,N-diethylformamide), which is not dependent on the synthetic conditions [48]. But it is interesting that the products are acutely dependent on the variable conditions employed if the identical reactants in DMF solvent system (DMF = N,N-dimethylformamide).…”

Hybrid organic–inorganic crystal structure of 4-(dimethylamino)pyridinium dimethylammonium tetrachloridolead(II)

“…The thick-walled vial was placed in the oven for 11 days at 373 K. Clear, colorless crystals of the title compound that were suitable for single-crystal X-ray diffraction were obtained. The DMA is present in the lattice due to the in situ degradation of DMF, which can occur at the reaction temperature (Burrows et al, 2008).…”

Hydrogen Adsorption on Metal Organic Framework Materials for Storage Applications

“…(NO 3 ) 4 [154] ( see Figure 4.12) and several further systems have been identified. [161,183,225] This is thought to be a kinetic trapping effect. The corresponding isobars are shown in Figure 4.11.…”