文摘
Activation of the secondary assembly instructions in the mononuclear pyrazine imide complexes [CoIII(dpzca)2](BF4) or [CoII(dpzca)2] and [NiII(dpzca)2] has facilitated the construction of two robust nanoporous three-dimensional coordination polymers, [CoIII(dpzca)2Ag](BF4)2路2(H2O) [1路2(H2O)] and [NiII(dpzca)2Ag]BF4路0.5(acetone) [2路0.5(acetone)]. Despite the difference in charge distribution and anion loading, the framework structures of 1路2(H2O) and 2路0.5(acetone) are isostructural. One dimensional channels along the b-axis permeate the structures and contain the tetrafluoroborate counterions (the CoIII-based MOF has twice as many BF4鈥?/sup> anions as the NiII-based MOF) and guest solvent molecules. These anions are not readily exchanged whereas the solvent molecules can be reversibly removed and replaced. The H2, N2, CO2, CH4, H2O, CH3OH, and CH3CN sorption behaviors of the evacuated frameworks 1 and 2 at 298 K have been studied, and modeled, and both show very high selectivity for CO2 over N2. The increased anion loading in the channels of CoIII-based MOF 1 relative to NiII-based MOF 2 results in increased selectivity for CO2 over N2 but a decrease in the sorption kinetics and storage capacity of the framework.
