Cheng Hongtao, Wang Qian, Bai Junfeng
Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry & Chemical Engineering, Shaanxi Normal University, Xi'an, 710062, P. R. China.
School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing, 211816, P. R. China.
Chemistry. 2023 Jan 18;29(4):e202202047. doi: 10.1002/chem.202202047. Epub 2022 Dec 7.
The solvothermal reactions of CoCl ⋅ 6H O, 3,5-pyridinedicarboxylic acid (H L) and isonicotinic acid (HL )/3-amino isonicotinic acid (HL )/3-chloro isonicotinic acid (HL ) successfully led to three tfz-d topological pillar-layer [Co (μ-F) (COO) (NC H ) ] cluster-based MOFs, namely, [Co (μ-F) (L) (L ) ⋅ 2DMA] ⋅ DMA ⋅ 2H O (SNNU-Bai76, SNNU-Bai=Shaanxi Normal University Bai's group), [Co (μ-F) (L) (L ) ⋅ 2H O] ⋅ 2DMA ⋅ 2H O (SNNU-Bai77) and [Co (μ-F) (L) (L ) ⋅ 2H O] ⋅ 2DMF ⋅ 2H O (SNNU-Bai78). With the 2D pore channels in SNNU-Bai76 and SNNU-Bai77 being tuned to the 1D pore channel in SNNU-Bai78, C H and C H adsorption uptakes are apparently improved and the IAST selectivities of C H /CH and C H /CH almost remain, which indicate that SNNU-Bai78 may be one potential separation material for the pipeline natural gas purification. These were further confirmed by the breakthrough experiments for the simulated pipeline natural gas (C H /C H /CH : 5/10/85 gas mixture) of three isostructural MOFs. Furthermore, GCMC simulations revealed that due to one of the pore channels blocked by Cl atoms in a couple of 3-chloro isonicotinic acid with the changed conformation as the pillar, the pore wall of the formed 1D pore channel in SNNU-Bai78 may interact with the adsorbed C H or C H molecule more strongly, for which more atoms of framework at the new adsorption site will interact with the adsorbed gas molecule by more intermolecular interactions. This was also evidenced by the increased binding energies, being consistent with the tuning of adsorption enthalpies for C H and C H gas molecules, and the reduced C H and C H gas diffusion coefficients in SNNU-Bai78. Very interestingly, this work is the first example of finely tuning the pore connectivity of MOFs toward strengthened host-guest interactions for the gas adsorption and separation.
CoCl₂⋅6H₂O、3,5 - 吡啶二甲酸（H₂L）与异烟酸（HL⁰）/3 - 氨基异烟酸（HL¹）/3 - 氯异烟酸（HL²）的溶剂热反应成功合成了三种基于tfz - d拓扑柱层[Co₂(μ - F)(COO)₂(NC₅H₄)₂]簇的金属有机框架材料，即[Co₂(μ - F)(L)(L⁰)₂⋅2DMA]⋅DMA⋅2H₂O（SNNU - Bai76，SNNU - Bai = 陕西师范大学白课题组）、[Co₂(μ - F)(L)(L¹)₂⋅2H₂O]⋅2DMA⋅2H₂O（SNNU - Bai77）和[Co₂(μ - F)(L)(L²)₂⋅2H₂O]⋅2DMF⋅2H₂O（SNNU - Bai78）。随着SNNU - Bai76和SNNU - Bai77中的二维孔道调整为SNNU - Bai78中的一维孔道，C₂H₂和C₂H₄的吸附量明显提高，且C₂H₂/CH₄和C₂H₄/CH₄的IAST选择性几乎保持不变，这表明SNNU - Bai78可能是一种用于管道天然气净化的潜在分离材料。三种同构金属有机框架材料对模拟管道天然气（C₂H₂/C₂H₄/CH₄∶5/10/85气体混合物）的突破实验进一步证实了这一点。此外，巨正则蒙特卡罗模拟表明，由于在几个3 - 氯异烟酸中作为支柱的构象发生变化，其中一个孔道被Cl原子阻塞，在SNNU - Bai78中形成的一维孔道的孔壁可能与吸附的C₂H₂或C₂H₄分子相互作用更强，因为在新的吸附位点框架中有更多原子将通过更多分子间相互作用与吸附的气体分子相互作用。结合能增加也证明了这一点，这与C₂H₂和C₂H₄气体分子吸附焓的调整以及SNNU - Bai78中C₂H₂和C₂H₄气体扩散系数的降低一致。非常有趣的是，这项工作是首次通过精细调节金属有机框架材料的孔连通性来增强主客体相互作用以实现气体吸附和分离的实例。
