New achievements of Professor Deng Hexiang's team in MOF materials research: from cheap small ligands to super large mesoporous MOF

Recently, Professor Deng Hexiang's team from school of chemistry and molecular science of Wuhan University has made the latest achievements in the field of synthesis and design of mesoporous (pore size > 2 nm) mesoporous metal organic framework (MOF) In this work, two principles of pore size construction and expansion of MOF are proposed, which provide important guidance for the synthesis of mesoporous MOF with large size channels The research results were published in J am Chem SOC (DOI: 10.1021 / JACS 8b11230) under the title of "mesoporous cases in chemical robot MOFs created by a large number of vertices with reduced connectivity" MOF material is a kind of crystalline porous material based on the coordination bond of organic molecules The pore size and channel size are the key indicators of these molecular based porous materials The channel size determines how much guest molecules can enter into the pore, while the pore size determines the number of guest molecules that can be accommodated in the pore Compared with microporous MOF, mesoporous MOF can hold larger guest molecules Therefore, the study of MOF can be extended from traditional gas related applications to larger guest molecules In recent years, Professor Deng Hexiang's team has made a series of research progress in the research of mesoporous MOF, revealed the interaction between mesoporous MOF and biological macromolecules, inorganic clusters, nanoparticles and other objects, and demonstrated the application potential of mesoporous MOF in catalysis, drug release, gene therapy, energy storage and other aspects However, how to synthesize MOF with mesoporous pores is the key to its application Most of the current synthesis methods often rely on the expansion of rigid organic ligands, and the expansion and extension of organic ligands in the synthesis often need to invest a lot of manpower and material resources, and involve complex synthesis and separation process This greatly limits the development of mesoporous MOF and its application in many fields Therefore, it is urgent to develop a method to construct mesopores based on small molecular building units with small size and low cost In this study, Professor Deng Hexiang's team found that when the number of connections of the vertices forming the channel polyhedron is fixed, the maximum size of the channel is positively related to the number of vertices; the growth rate of the size of the mesopore is determined by the number of connections of the vertices forming the mesopore When the number of vertices that make up the channel polyhedron is basically the same, reducing the number of vertex connections can effectively increase the size of the channel [2-C, 3-C] this connection is the minimum number of connections required to form a three-dimensional structure, and also the best way to expand the size of the channel Based on the above ideas, the team members selected two types of nodes with a large number of nodes and [2-C, 3-C] the lowest connection possibility as the basis, through the smaller organic ligand, 1h-pyrazole-4-carboxylic acid, Two new types of mesoporous MOF (mof-818 and mof-919) were synthesized by h2pyc) and many kinds of metal nodes based on cheap metals (such as Al, Fe, Cu, etc.) The size of the ligands is only 0.4 nm, and the maximum pore size of the constructed ligands is 6.0 nm (mof-919) The ratio of pore size to ligand size is as high as 15 times, which is the largest reported pore size to ligand ratio These novel mesoporous MOF materials, mof-818 and mof-919, can efficiently load biomacromolecules such as insulin and vitamin B12, and exhibit excellent water stability in aqueous solutions with pH = 2-12 Combined with the low cost and good biocompatibility of these MOFs, these mesoporous MOFs have high application value and broad prospects in the application of biomacromolecules and drug molecular loading The study was also selected as a cover article by JACS.