Eaby Alan C, Darwish Shaza, Wang Shi-Qiang, Bezrukov Andrey A, Sensharma Debobroto, Shipman Angela, Solanilla Carlos J, Space Brian, Mukherjee Soumya, Zaworotko Michael J
Bernal Institute and Department of Chemical Sciences, University of Limerick, Limerick V94 T9PX, Ireland.
Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27607, United States.
J Am Chem Soc. 2025 Jan 15;147(2):1813-1822. doi: 10.1021/jacs.4c13797. Epub 2025 Jan 2.
2D and 3D porous coordination networks (PCNs) as exemplified by metal-organic frameworks, MOFs, have garnered interest for their potential utility as sorbents for molecular separations and storage. The inherent modularity of PCNs has enabled the development of crystal engineering strategies for systematic fine-tuning of pore size and chemistry in families of related PCNs. The same cannot be said about one-dimensional (1D) coordination polymers, CPs, which are understudied with respect to porosity. Here, we report that permanent porosity is exhibited by the previously reported family of linear (L) 1D porous CPs, PCPs, of formula [M(bipy)(NO)(HO)]n (L-chn-1-M-NO3: M = Co, Ni; bipy = 4,4'-bipyridine). Their pore structure comprises 1D channels sustained by three types of directional interaction: coordination bonds; hydrogen bonds; offset π-π interactions. Heating L-chn-1-M-NO3 in vacuo or above 383 K resulted in removal of the aqua ligands and concomitant transformation to nonporous anhydrate phases ZZ-chn-1-Co-NO3 (ZZ = zigzag) and HT-Ni. Exposure of these anhydrate phases to ambient humidity resulted in regeneration of L-chn-1-M-NO3. That L-chn-1-M-NO3 exhibits permanent porosity was supported by CO and water sorption measurements, which afforded reversible type I and stepped (S-shaped) isotherm profiles, respectively, making this work the first demonstration of reversible water sorption in a 1D PCP. The water sorption properties are pertinent to atmospheric water harvesting: onset of uptake at ca. 12% relative humidity; activation required only mild heat or vacuum; relatively fast adsorption/desorption kinetics; performance retained over >100 adsorption/desorption cycles. We project water harvesting productivity of L-chn-1-M-NO3 of 3.3 L kg d, on par with some leading MOF desiccants. DFT and Monte Carlo simulations provide insights into the structure of water molecules in the channels, provide their influence on the host framework, and provide a plausible argument for the experimental water vapor isotherms. This work demonstrates that easily scalable 1D PCPs, a potentially vast class of materials, can exhibit porous structures sustained by three types of directional supramolecular synthons and offer desirable water sorption properties.
以金属有机框架（MOF）为例的二维和三维多孔配位网络（PCN），因其作为分子分离和存储吸附剂的潜在用途而备受关注。PCN固有的模块化特性使得人们能够开发晶体工程策略，对相关PCN家族的孔径和化学性质进行系统微调。而对于一维（1D）配位聚合物（CP），情况则有所不同，其孔隙率方面的研究较少。在此，我们报道了此前报道的通式为[M(bipy)(NO)(H₂O)]ₙ的线性（L）1D多孔CP家族（PCP）表现出永久孔隙率（L-chn-1-M-NO₃：M = Co、Ni；bipy = 4,4'-联吡啶）。它们的孔结构由三种类型的定向相互作用维持形成一维通道：配位键、氢键和错位π-π相互作用。在真空中或高于383 K加热L-chn-1-M-NO₃会导致水合配体去除，并伴随转变为无孔无水相ZZ-chn-1-Co-NO₃（ZZ = 之字形）和HT-Ni。将这些无水相暴露于环境湿度下会使L-chn-1-M-NO₃再生。CO和水吸附测量结果支持了L-chn-1-M-NO₃具有永久孔隙率，测量分别得到了可逆的I型和阶梯状（S形）等温线，这使得这项工作首次证明了1D PCP中存在可逆水吸附。水吸附特性与大气水收集相关：在约12%相对湿度时开始吸水；只需温和加热或真空即可活化；吸附/解吸动力学相对较快；在超过100次吸附/解吸循环中性能保持稳定。我们预计L-chn-1-M-NO₃的水收集生产率为3.3 L kg⁻¹ d⁻¹，与一些领先的MOF干燥剂相当。密度泛函理论（DFT）和蒙特卡罗模拟为通道中水分子的结构、它们对主体框架的影响提供了见解，并为实验水蒸气等温线提供了合理的解释。这项工作表明，易于扩展的1D PCP（一类潜在的大量材料）可以展现出由三种类型的定向超分子合成子维持的多孔结构，并具有理想的水吸附特性。
