Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University , Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.
CREST, Japan Science and Technology Agency (JST) , 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
J Am Chem Soc. 2017 Jun 14;139(23):7886-7892. doi: 10.1021/jacs.7b02402. Epub 2017 May 24.
The development of highly porous metal-organic frameworks (MOFs) is greatly sought after, due to their wide range of applications. As an alternative to the development of new structures, we propose to obtain new stable configurations for flexible MOFs by insertion of polymeric guests. The guests prevent the otherwise spontaneous closing of the host frameworks and result in stable opened forms. Introduced at a fraction of the maximal capacity, polymer chains cause an opening of the occupied nanochannels, and because of the MOF reticular stiffness, this opening is propagated to the neighboring nanochannels that become accessible for adsorption. Composites were obtained by in situ polymerization of vinyl monomers in the nanochannels of an otherwise nonporous MOF, resulting in homogeneously loaded materials with a significant increase of porosity (S = 920 m/g). In addition, by limiting the accessible configurations for the framework and forbidding the formation of a reactive intermediate, the polymeric guest prevented the thermal degradation of the host MOF even at very low loading (as low as 3 wt %) and increased its stability domain by more than 200 °C.
高度多孔的金属-有机骨架（MOFs）的开发受到广泛关注，因为它们具有广泛的应用。作为开发新结构的替代方案，我们建议通过插入聚合物客体来获得柔性 MOFs 的新稳定构型。客体阻止了主体框架的自发闭合，从而产生了稳定的开放形式。以远低于最大容量的分数引入的聚合物链引起占据的纳米通道的打开，并且由于 MOF 网状刚度，这种打开会传播到相邻的纳米通道，这些纳米通道可用于吸附。通过在原本无孔的 MOF 的纳米通道中进行乙烯基单体的原位聚合，获得了复合材料，从而使材料具有均匀的负载和显著增加的孔隙率（S = 920 m/g）。此外，通过限制框架的可及构型并禁止形成反应性中间产物，即使在非常低的负载（低至 3wt%）下，聚合物客体也能防止主体 MOF 的热降解，并使它的稳定域增加超过 200°C。
