Abstract
Activation of the secondary assembly instructions in the mononuclear pyrazine imide complexes [Co-III(dpzca)(2)](BF4) or [Co-II(dpzca)(2)] and [Ni-II(dpzca)(2)] has facilitated the construction of two robust nanoporous three-dimensional coordination polymers, [Co-III(dpzca)(2)Ag](BF4)(2).2(H2O) [1.2(H2O)] and [Ni-II(dpzca)(2)Ag]BF4.0.5(acetone) [2.0.5(acetone)]. Despite the difference in charge distribution and anion loading, the framework structures of 1.2(H2O) and 2..5(acetone) are isostructural. One dimensional channels along the b-axis permeate the structures and contain the tetrafluoroborate counterions (the Co-III-based MOF has twice as many BF4- anions as the Ni(II)-based MOF) and guest solvent molecules. These anions are not readily exchanged whereas the solvent molecules can be reversibly removed and replaced. The H-2, N-2, 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 N-2. The increased anion loading in the channels of Co(III)-based MOF 1 relative to Ni(II)-based MOF2 results in increased selectivity for CO2 over N-2 but a decrease in the sorption kinetics and storage capacity of the framework.