Proton -conducting lanthanide metal-organic frameworks: a multifunctional platform

Lanthanide metal-organic frameworks (LMOFs) have established themselves as promising proton-conducting materials among all types of porous coordination polymers and covalent organic frameworks. The structural diversity of LMOFs and high oxophilicity with a high coordination number of lanthanide ions make LMOFs a standout material for proton conduction. In the last few years, ample research efforts have been devoted to designing and developing proton-conducting lanthanide metal-organic frameworks (PCLMOFs). Some of the PCLMOFs have shown great potential with proton conductivity comparable to that of commercially used perfluorosulfonic acid (PFSA) polymers for proton-exchange membranes (PEMs) in fuel cells. At present, it is apparent that PCLMOFs are becoming a potential platform to explore other functional properties (e.g. fluorescence sensing, gas adsorption, molecular magnetism, impedance sensing, ferroelectricity, and nonlinear optics). The intrinsic structural features of PCLMOFs inevitably bring the opportunity to introduce the multifunctional character of such materials. Therefore, any scope for additional functional properties must be investigated for this class of material. In this article, we concisely discuss the design strategy and structural features of some multifunctional PCLMOFs. Furthermore, multifunctional properties of some excellent PCLMOFs are reviewed. In addition, the prospect of PCLMOFs is briefly discussed in the context of real-world material applications.