Supramolecular Metallogels Constructed Form Amide Derivatives And Their Catalytic Applications

Nanomaterials are widely used in energy,medical treatment,catalysis,sensing and other fields because of their small size,large specific surface area and unique properties.Supramolecular metallogel is a three-dimensional network formed by the self-assembly of small organic molecules containing metals or the co-assembly of small molecules with coordination groups and metal ions,thus immobilizing solvents.It is a kind of nanomaterials with wide prospects.The coordination of small organic molecules can disperse metal ions in the interior of the gel,which has the characteristics of large dispersion and strong stability,so that it shows a high catalytic efficiency in the application of catalysis.In this paper,a series of composite catalytic materials containingγ-Fe₂O₃ nanoparticles were prepared by using supramolecular metallogels formed by Fe³⁺and small organic molecules as precursors,and their catalytic activity in catalytic reduction of aromatic nitro compounds was investigated.Specific research is as follows:（1）A novel metallogel（Fe（III）-2BN3）,based on N₄,N₄’-di（pyridin-3-yl）-[2,2’-bipyridine]-4,4’-dicarboxamide（2BN3）and Fe（NO₃）_3,was synthesied.According to the IR spectrum and PXRD,the self-assembly pattern of（Fe（III）-2BN3）was proposed.The gels were characterized by modern analytical techniques such as rotational rheology,PXRD,IR and SEM.The results showed that the supramolecular gels had good mechanical properties and excellent thermal reversibility properties,the hydrogen bond between molecules and the coordination with Fe³⁺were the main driving forces for the formation of the gels.（2）A Fe-base metallogel（Fe（III）-2BN3）was prepared via metal coordinate interation between Fe（NO₃）₃ and 2BN3.Fe（III）-2BN3 was used as the precursor for the fabrication of low-costγ-Fe₂O₃-Fe/C-modified mesorprous carbon catalyst through carbonization under an N₂atmosphere at high temperature.The metallogel offered an ultra uniform distribution of the iron,so that theγ-Fe₂O₃ and Fe nanoparticles（NPs）were uniformly distributed in the 3D carbon architecture with the average size of approximate 15 nm.The obtainedγ-Fe₂O₃-Fe/C catalyst show high activity and high chemoselectivity in reduction of different functionalized nitroarenes to the corresponding anilines giving yields of the target products close to 100%when using hydrazine hydrate as the reducing agent.In addition,theγ-Fe₂O₃-Fe/C catalyst was recyclable because of the magnetism of theγ-Fe₂O₃ active sites.The catalytic activity of theγ-Fe₂O₃-Fe/C catalyst was not obviously decreased after being recycled five times.Therefore,theγ-Fe₂O₃-Fe/C catalyst has great potential for future applications in the chemoselective hydrogenation of nitrobenzenes.（3）A novelγ-Fe₂O₃ nanocomposites were successfully synthesized via pyrolysis a Fe-base metallogel that prepared from N,N’,N’’-tris（3-pyridyl）trimesic amide and Fe（NO₃）₃.The nanostructures and ultimate composition of synthesized composites were well characterized by many techniques,such as X-ray diffraction（XRD）,transmission electron microscopy（TEM）,and X-ray Photoclectron Spectroscopy（XPS）.And the preparedγ-Fe₂O₃ nanocomposites with optimized preparation conditions as new catalyst displayed excellent catalytic performance on the reduction reaction of p-nitrophenol,demonstrating potential applications for environmental governance and composite materials.