Study On The Syntheses,Surface Modifications,and Applications Of Nanoscale Coordination Polymers

Coordination polymers(CPs)are a class of porous hybrid materials composed of repeating units of inorganic metal nodes(metal ions/clusters)and organic ligands that are connected through coordination bonds and self-assembly.According to the self-limitation property of the coordination environment,CPs can be generally distinguished into CPs with crystalline structure,also known as metal-organic framework materials(MOFs).CPs with amorphous structure become nano-scale coordination polymers(NCPs).In addition to the advantages of good stability,easy recovery,adjustable porosity and high internal surface area,CPs also have good optical,thermal and magnetic properties related to advanced functional materials,and have a wide range of potential applications in the fields of separation,catalysis,energy and biomedicine.In order to provide coordination polymers with even more diverse and sophisticated properties,efforts have been made to synthesize coordination polymers with various metal ions and organic ligands and to introduce new physical and chemical properties through functionalization of the materials with active metal sites and functional groups.Therefore,exploring the synthesis of advanced functional coordination polymers with better performance and novel structures remains of great scientific significance.This paper first functionalizes existing coordination polymers through post-synthetic modification methods,selectively introducing organic functional groups under the condition of maintaining the original topological structure,in order to regulate and improve the original physical and chemical properties and thus endow them with new physical and chemical properties.Secondly,novel coordination polymer nanoparticles with multifunctional properties are designed using clinically used functional molecules as organic ligands,displaying attractive potential for application in biomedical imaging and therapy.The specific research content is as follows:1.We report a universal and efficient surface crown ether coordination strategy(CESC)that decorates the MOFs surface with carboxylated crown ether molecules,which coordinate with the exposed metal sites on the MOFs surface.On the one hand,the surface-modified amphiphilic crown ether molecules shield the exposed metal sites and ligands,significantly enhancing the interfacial interactions between the nanoparticle and solvent molecules at the solid-liquid interface,thereby greatly improving the dispersion ability of MOFs in various media.On the other hand,due to the inherent cavity of crown ether molecules,surface-modified crown ether molecules do not block the pores of MOFs compared to other types of functional groups,maintaining the porous structure and the ability of guest molecules to enter and exit the original MOFs material.We used crown ether-modified Cu-MOF(HKUST-1)to efficiently disperse in water and oil phases,as a phase transfer catalyst to promote the azide-alkyne cycloaddition click reaction of azides with alkynes in two-phase systems,which can facilitate effective mixing of substrates between immiscible two-phase solutions and greatly enhance the reaction rate of Cu-catalyzed click cycloaddition.Furthermore,we demonstrated that crown ether-modified MOFs nanoparticles can rapidly form highly uniform mixed matrix membranes in six different polar polymer matrices,including polystyrene,polyimide,and polystyrene sulfonate.These highly uniform mixed matrix membrane materials exhibit better gas adsorption and selectivity,as well as higher dye filtration capacity.This method is expected to overcome the processability barriers of MOFs as a crystal powder material and improve the potential for industrial catalysis and biomedical applications of MOFs.2.Efficient extraction of uranium from seawater has been an important challenge in the nuclear power industry.To solve this problem,21-crown 7 ether with metal ion selectivity was introduced into the highly stable metal-organic framework PCN-222.The synthesized 21-crown7 ether modified metal-organic framework material(PCN-222-CE)showed high uranyl ion adsorption capacity in both simulated and natural seawater.In natural seawater,the extraction capacity of PCN-222-CE for uranyl is 10 times that of cesium,indicating that the adsorbent has high selectivity for existing.The results of X-ray photoelectron spectroscopy(XPS)and Fourier transform infrared spectroscopy(TI-IR)show that PCN-222-CE can not only restrict the entry of other large interfering ions,but also enhance the domain limiting effect of uranyl ions in the nanopore through coordination interaction,so as to have high affinity and high selectivity.This study provides a new way to efficiently adsorb uranium from seawater.This work may provide a new approach for highly efficient sorption of uranium from seawater.3.Clinical computed tomography(CT)usually requires a high dose of iohexol contrast agent,which can lead to oxidative stress,apoptosis,and kidney failure in severe cases of contrast nephropathy,especially in patients with chronic renal failure,which further burdens the kidney during CT imaging with this contrast agent.Therefore,a biodegradable nano-scale coordination polymer contrast agent(IO-NPs)is formed by self-assembly of iohexol and aluminum ion coordination.IO-NPs can extend CT imaging time of rats with chronic renal failure by 5 times as much as iodohexol alone,compared with commonly used small molecule contrast agents.In addition,IO-NPs nanoparticles preferentially accumulate in liver tissue to avoid further kidney damage in chronic renal failure model rats.In conclusion,we propose a novel strategy for designing a nephroprotective contrast agent that reduces the risk of contrast nephropathy.