SYNTHESIS OF TWO-DIMENSIONAL ORGANIC FRAME MATERIALS: CLASSIFICATION, APPLICATIONS, PROBLEMS AND MODIFICATION APPROACHES

Organic framework materials, including MOFs and HOFs, are widely used in multiple fields. MOFs are formed by the self-assembly of inorganic metal centers and organic ligands, and there are various types such as IRMOFs and ZIFs. Post-synthetic modification (PSM) can expand their functional groups. HOFs connect building units through hydrogen bonds. They have advantages like mild preparation conditions and good solution-processing performance, but the characteristics of hydrogen bonds also limit their development. Two-dimensional MOFs combine the advantages of MOFs and ultrathin two-dimensional materials. There are two preparation strategies: "top-down" and "bottom - up". The "top-down" method, including physical and chemical exfoliation methods, can exfoliate bulk MOFs into nanosheets, but there are problems such as uneven product thickness and low yield. The "bottom-up" methods, such as the solvothermal method, interface synthesis method, and auxiliary synthesis method, can prepare nanosheets with uniform thickness, but each has its pros and cons. Overall, organic framework materials have broad prospects, but they still face challenges in synthesis, performance optimization, etc., and further research and improvement are needed.