Metal-organic framework constructed by flexible ligands: A versatile platform towards efficient fluorescence sensing, adsorption separation and heterogeneous catalysis

Compared with MOFs based on rigid ligands (RL-MOFs), MOFs with flexible ligands (FL-MOFs) have many advantages, such as highly flexible structure and deformable periodic framework, and producing reversible structural changes under external stimulation. FL-MOFs usually contain abundant fluorophores, which can generate specific fluorescence response under the stimulation of specific substances. In addition, the macroporous structure displayed by FL-MOFs also ensures that the substrate of the catalytic reaction is easy to contact with the internal active sites, and is conducive to transport raw materials and products, thus promoting the catalytic reaction. Therefore, FL-MOFs have potential applications and huge development space in the fields of gas storage and separation, fluorescence sensing, and catalysis. In this review, the structural design and selfassembly strategy of FL-MOFs are firstly introduced. On this basis, the cutting-edge research progress of FLMOFs in recent years in the fields of fluorescence sensing (anions and cations, organic molecules, biomolecules), gas adsorption and separation, and catalysis are reviewed, and the current shortcomings and challenges of FL-MOFs are proposed. Finally, combined with current research status, the application prospect and development trend of FL-MOFs are prospected.