| Metal-Organic Frameworks?MOFs?have highly porous structure,uniform spatial dispersion of components,tunable pore sizes and topologies as well as hybrid organic-inorganic nature.It has shown wide application prospects in many fields,such as catalysis,sensing,electrochemistry,substance separation and purification,as well as gas storage or drug delivery.Compared with traditional inorganic porous materials,MOFs are made up of inorganic secondary building units?SBUs,?which are connected by single or multiple organic linkers via coordination bonds.The structure and porosity of MOFs can be pre-designed or post-synthesized by sensible regulation of the type,morphology,size,and functional groups of the secondary structural units to achieve controlled synthesis of the target material.Aromatic polycarboxylic acid ligands are beneficial to construct novel functional complexes due to the large number of carboxyl coordination sites,rich coordination modes and rigidity of aromatic rings.Therefore,in this thesis,three kinds of trinuclear iron cluster-based carboxylic acid MOFs were constructed by solvothermal synthesis with aromatic polycarboxylic acid coordination as the core,and the properties of single crystal structure and gas adsorption were studied in depth.The research contents are as follows:1.4',4'',4'''-?1,3,5-triazine-2,4,6-triyl?tris?[1,1'-biphenyl]-4-carboxylic acid??abbreviated as H3tapb?was selected to react with Fe salt.Two trinuclear ferrite carboxylic acid MOFs were obtained by adjusting the coordination of the auxiliary ligands.[Fe3??3-O?2?tapb?2?Py?2]·3Cl?1?and[Fe3??3-O?2?tapb?2?H2O?2]·3Cl?2?.Observed by optical microscopy,the crystal shapes of the two are diamond-shaped?1?and columnar?2?,respectively.The single crystal structure analysis showed that 1,2 have very similar host skeletons,in which the coordination environment of the SBUs trinuclear ferrite clusters is different,and the position of the pyridine coligand in 1 is replaced by water in 2.In addition,both are double-inserted structures,and there is a one-dimensional diamond-shaped hole in the a direction.Using solvent-assisted metal exchange strategy,all iron atoms in MOFs?1?were substituted to obtain chromium-based MOFs?1-Cr?.The adsorption performance of various gases showed that the gas adsorption properties of MOFs after substitution were observed,and structural stability has been significantly improved.2.3,3?,5,5?-terphenyltetracarboxylic acid?H4tptc?reacted with Fe salt to synthesize a resultant chiral 3D complex with a triple helix axis Fe107??3-O?23?tptc?33?DEF?12?3?,the trinuclear ferrite cluster is SBUs.Solid circular dichroism showed that 3 was a racemic mixture;magnetic analysis revealed that 3 had weak antiferromagnetic properties.In addition,gas adsorption tests indicate that the porosity of 3 is much larger than 1 and 2,resulting in a much higher N2 adsorption of 3 than 1 and 2. |
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