Crystal-Size Effects on Carbon Dioxide Capture of a Covalently Alkylamine-Tethered Metal-Organic Framework Constructed by a One-Step Self-Assembly

To enhance the carbon dioxide (CO(2)) uptake of metal-organic frameworks (MOFs), amine functionalization of their pore surfaces has been studied extensively. In general, amine-functionalized MOFs have been synthesized via post-synthetic modifications. Herein, we introduce a one-step construction of a MOF ([(NiL(ethylamine))(BPDC)] = MOF(NH2); [NiL(ethylamine)](2+) = [Ni(C(12)H(32)N(8))](2+); BPDC(2−) = 4,4‘-biphenyldicarboxylate) possessing covalently tethered alkylamine groups without post-synthetic modification. Two-amine groups per metal centre were introduced by this method. MOF(NH2) showed enhanced CO(2) uptake at elevated temperatures, attributed to active chemical interactions between the amine groups and the CO(2) molecules. Due to the narrow channels of MOF(NH2), the accessibility to the channel of CO(2) is the limiting factor in its sorption behaviour. In this context, only crystal size reduction of MOF(NH2) led to much faster and greater CO(2) uptake at low pressures.