Synthesis Of Ru-Modified Zirconium-based Organometallic Frame Materials And Their Catalytic C-H Bond Activation

Nitrogenous molecules are important components of most bioactive molecules,pharmaceutical intermediates,natural products,and functional materials.Amination reaction,as one of the oldest reactions in organic chemistry,can accurately introduce nitrogen atoms into the molecule,thus realizing the guided transformation of molecular biological activity and pharmaceutical and chemical properties.Most of the traditional amidation reactions require higher reaction temperatures to promote the coupling reaction,but there are some limiting factors such as the easy decomposition of acyl chloride,more chemical wastes,and harsh reaction conditions.Therefore,more and more scientific research focuses on the synthesis of effective catalysts to reduce the reaction barrier to catalyze the amidation reaction.At present,the amidation of small molecules of aldehydes,alcohols,and ketones is mainly catalyzed by metal catalysts such as noble metal complexes or nitrogen heterocyclic carbene transition metal complexes.The application of these methods in the industrial field is greatly limited due to the narrow range of substrates,the presence of metal ion residues,the difficulty in separating the products,and the high cost.How to overcome the above shortcomings and build a stable and efficient catalytic reaction system to achieve the efficient synthesis of amide is an urgent research problem.Metal-organic framework materials（MOFs）are a kind of crystalline porous materials with permanent voids formed by metal ions/clusters and highly symmetrical organic ligands through the strong coordination between metal and coordination atoms.MOFs have an accurate microchemical environment,clear active sites,and rich structural pre-design.A series of MOFs with specific functions can be obtained through the regulation of metal ions/clusters and ligands and the post-synthesis modification of MOFs.Therefore,MOFs have gradually become the best platform for designing and constructing heterogeneous catalysts.Zirconium-based organometallic framework materials（Zr MOFs）,due to the strong coordination of Zr-O bonds,have shown excellent thermal and chemical stability.Photocatalysis is clean and pollution-free,and the small molecules of photosensitizers can jump to the excited state under the excitation of light to achieve efficient oxidation of small molecules using electron transfer.Based on the above advantages,in this paper,zirconium-based metal-organic framework materials（Zr-MOFs）were modified and used as heterogeneous photocatalysts to photocatalytic aldehyde molecules to generate acyl chloride active intermediates in situ.Amides and hydroxamic acid derivatives were efficiently synthesized through a simple one-pot reaction.In addition,this method was successfully applied to the synthesis of moclobemide,a drug commonly used to treat depression.In the first part of this paper,the photocatalyst fraction[Ru（dcbpy）（bpy）₂]Cl₂ and organic ligand 2,2`-methyl-5,5`-benzoic acid and other small molecules were mainly synthesized.PCN-700 and PCN-808 crystal materials were synthesized by solvothermal method and post-modified by the solvent-assisted method.The synthetic MOFs materials were analyzed by the ultra-depth of field optical microscopy,powder X-ray diffraction（PXRD）,ultraviolet-visible spectroscopy（UV-vis）,infrared spectra analysis（IR）,inductive coupled plasma emission spectrometer（ICP）and d nuclear magnetic resonance spectroscopy（NMR）.The experimental results showed that we successfully anchored the photocatalyst molecules in the crystal framework,and successfully obtained heterogeneous catalysts PCN-700 Ru and PCN-808 Ru with photocatalytic activity.In the second part of this paper,PCN-808-Ru was used as a heterogeneous photocatalyst to catalyze the oxidation of aldehyde hydrogen bonds,and a series of amidation products were obtained with a high yield.The experimental results show that this simple one-pot reaction has a wide range of substrates,a wide tolerance range for functional groups on aromatic aldehydes,and a high yield for electron-deficient or electron-rich groups at different positions.It has high reactivity to some aliphatic amines and aromatic amines,and can also achieve high product conversion to some pharmaceutical small molecules including moclobemide.In addition,the circulation experiment of the selected catalyst also proved that PCN-808-Ru could still maintain a good crystalline structure and stable catalytic performance after four cycles.In the last part,a series of hydroxamic acid products were synthesized by replacing amine molecules with hydroxylamine derivatives through literature research,which further broadened the practicability of the reaction system.