UoC‐7: A Bimetallic K‐Zn‐MOF with an Anionic Framework Based on Fluorinated Trimesate Ligands Exhibiting a Large CO2 Uptake

Abstract

AbstractIn solvothermal reactions of Zn(NO3)2×6H2O with K(H2mF‐BTC) or K(H2dF‐BTC) in DMF/ethanol or DMA/ethanol solvent mixtures, single crystals of the MOFs UoC‐7(1F) and UoC‐7(2F) were obtained crystallizing in the hexagonal space group P63/m (no. 176) (H3BTC: 1,3,5‐benzenetricarboxylic acid; mF‐/dF: mono‐/difluoro; DMF: N,N‐dimethylformamide; DMA: N,N‐dimethylacetamide; UoC: University of Cologne). According to the general composition [(CH3)2NH2][K2Zn3(mF‐/dF‐BTC)3(H2O)]×solvent, UoC‐7 consists of an anionic bimetallic framework. The charge is compensated by a (CH3)2NH2+ cation stemming from the (partial) hydrolysis of the solvent. The crystal structure shows large channels along the hexagonal [001] direction, which accommodate the cations as well as solvent molecules. Surface areas (SBET) of 2740 m2/g (UoC‐7(1F)) and 1643 m2/g (UoC‐7(2F)) were obtained from N2 sorption measurements. UoC‐7 shows structural similarities to the MOF NKU‐521 with a 5‐(1H‐tetrazol‐5‐yl)isophthalate linker. Both MOFs exhibit a 4,7,8T14 topology. Despite smaller channels in UoC‐7 compared to NKU‐521, the CO2 uptake is considerably higher (~164 cm3/g at 1 bar/293 K) being one of the highest CO2 uptakes observed up to now.