Hydrophobic metal-organic frameworks: Potential toward emerging applications

Abstract

Metal-organic frameworks, popularly known as MOFs, have come of age—thanks to custom-built design principles enabling them to serve a myriad of task-specific applications. In an era where >6000 new MOFs are annually published, driven by academic research, a new generation of MOFs that can find use in niche markets is on the rise. One of the foremost challenges that plague the translation of MOFs into materials suited for commercialization is their water-influenced degradation, largely accountable to hydrolytic instability and the ubiquity of water. Hydrophobic MOFs offer one of the most promising solutions which can enable these porous materials to leverage their functionalization guided properties even under extreme humid conditions, a criterion that application-ready materials should necessarily serve. In this contribution, our discussion focuses on the state-of-the-art hydrophobic MOFs and MOF-derived composites. Outlining a brief overview of the structure-property correlation aspects in each of these promising hydrophobic MOFs with little or no influence exhibited to water and/or humidity, a future outlook is put forward to enable potentially better design strategies leading to futuristic MOFs tolerant to water/moisture. Concise premise of this review allows us to limit our discussion to the design principles in action behind the most hydrophobic MOFs/derived composites reported thus far and to discuss their prime applications viz., oil/water separation inclusive of self-cleaning, hydrocarbon separation, and tackling marine oil spillage. When synergized, such improved porous material design approaches lean toward a greener environment of tomorrow.