Guest‐selective gate‐opening by pore engineering of two‐dimensional Kagomè lattice porous coordination polymers

Abstract

Abstract Porous coordination polymers (PCPs) with pore decoration have been used as materials for excellent storage and separation functions. The cooperative properties of flexible PCPs can be utilized to achieve the separation of mixtures of gaseous molecules having highly similar properties. The key to efficient molecular recognition and separation lies in increasing the degrees of freedom of the structure without sacrificing the stability of the system. However, the mechanism study of such behavior is still scarce in the literature. Here, we focused on PCPs with two‐dimensional Kagomè lattice structures and functionalized the pores with various alkoxy pendant groups; this facilitated systematic tuning of the pore aperture size, the interlayer spacing, as well as the interactions between the host and adsorbed molecules. The combination of characterization techniques allowed us to observe a unique deformation of the lattice upon gas sorption, allowing the separation of gas molecules with similar physicochemical properties, such as propane and propylene. Key points Flexible porous coordination polymers (PCPs) can create an excellent mechanism for recognizing gases with very similar properties. Here, PCPs with a Kagomè framework, in which hexagonal (H) and triangular (T) pores are adjacent to each other, can achieve a high level of propylene/propane separation by controlling the cooperativity of the H‐T pores with ligand substituents.

Keywords

• gas separation
• metal‐organic framework
• porous coordination polymer
• soft porous crystal
• structural flexibility