Porous Metal–Organic Frameworks with Chelating Multiamine Sites for Selective Adsorption and Chemical Conversion of Carbon Dioxide

Abstract

A combination of carbon dioxide (CO₂) capture and chemical fixation in a one-step process is attractive for chemists and environmentalists. In this work, by incorporating chelating multiamine sites to enhance the binding affinity toward CO₂, two novel metal-organic frameworks (MOFs) [Zn₂(L)(2,6-NDC)₂(H₂O)]·1.5DMF·2H₂O (1) and [Cd₂(L)(2,6-NDC)₂]·1.5DMF·2H₂O (2) (L = N¹-(4-(1 H-1,2,4-triazole-1-yl)benzyl)- N¹-(2-aminoethyl)ethane-1,2-diamine, 2,6-H₂NDC = 2,6-naphthalenedicarboxylic acid, DMF = N, N-dimethylformamide) were achieved under solvothermal conditions. Both 1 and 2 possess high selectivity for adsorption of CO₂ over CH₄ at room temperature under atmospheric pressure. Moreover, 1 has one-dimensional tubular channels decorated with multiactive sites including NH₂ groups and coordination unsaturated Lewis acid metal sites, leading to efficient catalytic activity for chemical fixation of CO₂ by reaction with epoxides to give cyclic carbonates under mild conditions.