Design And Catalytic One Pot Reaction Of MOFs Nanosheet Materials

Metal organic framework materials?MOFs?are porous materials with high specific surface area and a large number of active sites,which are composed of organic ligands and metal ions or metal clusters.Over the past two decades,efforts have focused on the design and synthesis of new MOFs with different pore functions.As a new member of this family,the metal organic matrix nanocomposites have wide application prospects in many different fields.The 2D MOFs nanostructures,which inherit the advantages of MOFs and 2D materials,exhibit large specific surface area,adjustable structure,ultra-thin and unique molecular array,short diffusion path,abundant exposed active sites,and their infinite ordered porous structure.These aspects make MOFs nanosheet have more significant advantages than other 2D layered nano materials.However,it is still difficult to obtain high-yield MOFs nanosheet at present,and the general yield is less than 10%.Therefore,how to develop an efficient method to synthesize MOFs nanosheet has attracted people's interest.In this paper,two methods of preparing MOFs based nanosheet are introduced,and their structural characteristics and catalytic properties are studied.The paper is divided into four chapters:In the first chapter,we first introduced the preparation methods,structural characterization and performance research of MOFs nanosheet,and focused on the known preparation methods of MOFs nanosheet.In the second chapter,we selected the solvothermal reaction between Pb?NO₃?₂and H3TATMA to synthesize a two-dimensional lead metal organic framework?Pb MOF,Pb₄?OH?₂?TATMA?₂·x?solv?,H₃TATMA=4,4',4''-s-triazin-1,3,5-tripheny-ltrimethylaminobenzoic acid?with a van der Waals layered crystal structure.The 2D Pb-MOF can be further stripped and morphologically modified by high power probe ultrasound.For the first time,we have demonstrated a new method to prepare ultra-thin 2D Pb-MOF nanosheet by using Pb-MOF crystal intercalation material.With the addition of intercalation agent,the yield of 2D MOF nanosheet increased significantly.As a"molecular wedge",the intercalator can intercalate into 2D Pb-MOF nanosheet and expand the crystal space between adjacent MOF layers during the ultrasonic process.In a short time?1 h?,the?6.0±2 nm?2D MOF nanocomposites can be prepared by this stripping process with a yield of 17.7%.In addition,we show that the prepared 2D Pb-MOF nanosheet has much better heterogeneous catalytic efficiency than the corresponding bulk Pb MOF in the one pot series deacetalization Knoevenagel reaction.Our work has developed an efficient method to obtain 2D-MOF nanosheet,and emphasized the new opportunities of using2D MOF nanosheet as high catalytic material and wide application.In the third chapter,we use hydrotalcite as self sacrificing template to synthesize LDH@MOF sandwich nanostructure.The synthesis process consists of two steps:first,the flower shaped LDH is separated into uniform sized nano sheets by cell grinder,then the LDH nano sheets are used as substrates and self sacrificing templates to provide cobalt and nickel ions,and then the NiCo-LDH@MOF-74 is synthesized by adding organic ligands under solvothermal conditions.Due to the large surface charge and strong hydrophilicity of NiCo-LDH,it has a strong interaction with NiCo MOF-74,forming a stable structure.It is gratifying that NiCo-LDH@MOF-74 with Lewis acid center?NiCo cluster in NiCo MOF-74?and Bronsted base?hydroxyl group in NiCo-LDH?sandwich structure can be used as an efficient heterogeneous catalyst for three-component Biginelli reaction in solvent-free condition.Compared with the parent NiCo-LDH and MOF-74,it has good synergistic catalytic performance.In addition,this method provides a new idea for the synthesis of MOF nanosheet.In the fourth chapter,we summarize the catalytic one pot reaction of MOFs nanocomposites synthesized by two methods,which provides a new idea for the efficient preparation of MOFs nanocomposites in the future and its application in one pot reaction.