Transport tuning strategies in MOF film synthesis - a perspective

Metal-organic frameworks (MOFs), sometimes also known as coordination polymers, are a very versatile group of materials consisting of metal nodes and organic linkers forming a tunable porous structure that can exist in different structural phases. The capability to synthesise MOF films allows for application in many different fields such as separation, energy, and catalysis. This perspective aims to explore the transport mechanism and tuning strategies in different types of MOF thin films tailored for different applications. Intracrystalline transport, which has been widely studied, has been shown to successfully aid in the selective transport of different molecules by adjusting the MOF's pore structure and environment. However, in the context of thin film, it is also important to consider interframework (for mixed matrix membrane (MMM) thin film) or intercrystalline (for polycrystalline thin film) based transport as it also directly impacts the overall transport of the thin film. Here we highlight the current intracrystalline and intercrystalline/interframework transport tuning strategies, as well as chart a course for future transport tuning strategies tailored for current and future applications.