Partial Linker Substitution Strategy to Construct a Quaternary HKUST-like MOF for Efficient Acetylene Storage and Separation

Multicomponent metal–organic frameworks (MOFs)
have received
much attention as emerging materials capable of precisely programing
exquisite structures and specific functions. Here, we applied a partial
linker substitution strategy to compile an HKUST-1-like quaternary
MOF by introducing a bifunctional ligand into the well-known HKUST-1
structure. FUT-1, a new HKUST-like tbo topology MOF, was assembled with paddlewheel [Cu2(COO)4], triangular metallocycle pyrazole cluster Cu3(μ3-OH) (NN)3 building blocks,
and two distinct linkers. FUT-1 exhibited good mechanical
stability, water stability, and chemical stability (pH = 3–12)
in aqueous solutions. Moreover, the porous environments created by
this multicomponent primitive endow FUT-1 with high C2H2 storage and significantly selective separation
performance of C2H2/CO2. Dynamic
breakthrough experiments and ideal adsorbed solution theory calculations
further demonstrate that FUT-1 can selectively capture
C2H2 from C2H2/CO2 mixtures under ambient conditions. Based on grand canonical
Monte Carlo simulations, the high C2H2 separation
performance of FUT-1 is attributed to the π-complex
formed between the C2H2 molecule and the trinuclear
metallocycle clusters on the wall, which provides stronger affinity
for C2H2 recognition than the CO2 molecule.

多组分金属有机框架（metal–organic frameworks, MOFs）作为一类能够精准构筑精细结构并实现特定功能的新兴材料，受到了广泛关注。本文采用部分配体取代策略，将双功能配体引入经典HKUST-1结构中，合成了一种类HKUST-1的四元MOF。FUT-1是一种新型类HKUST的tbo拓扑结构MOF，由桨轮型[Cu₂(COO)₄]、三角金属环吡唑簇Cu₃(μ₃-OH)(NN)₃以及两种不同配体组装而成。FUT-1在水溶液中展现出优异的机械稳定性、水稳定性以及pH 3~12范围内的化学稳定性。此外，该多组分结构基元所构建的多孔环境，赋予FUT-1优异的乙炔（C₂H₂）存储能力以及显著的乙炔/二氧化碳（C₂H₂/CO₂）选择性分离性能。动态穿透实验与理想吸附溶液理论计算进一步证实，FUT-1可在常温常压条件下从乙炔/二氧化碳混合气体中选择性捕获乙炔。基于巨正则蒙特卡洛模拟，FUT-1的高乙炔分离性能可归因于乙炔分子与孔道内壁上的三核金属环簇之间形成的π络合物，该络合物对乙炔的结合亲和力强于二氧化碳分子。