Synthesis And Application Of Covalent Organic Frameworks

Covalent organic frameworks have shown excellent performance in the range of applications including gas storage,gas separation,catalysis,energy storage,energy conversion and biomedical fields on account of their good porous structure and crystallinity.Herein,we successfully synthesized a series of covalent organic frameworks which can be utilized in many fields.?1?Post-modification strategy was used to synthesize sulfur-containing covalent organic framework?S-COF?by thiol-ene“click”reaction from a propenyl-functionalized COF?P-COF?.Furthermore,the obtained S-COF was used as matrix to successfully prepare COF-supported Au NPs?Au-S-COF?with narrow size distribution?4.2±1.2 nm?and high distribution density,which shows excellent catalytic activities in reduction of4-nitrophenol with remarkable stability and recyclability.In the Au-S-COF heterogeneous catalytic system,the strong anchoring ability between Au NPs and sulfur-containing groups over COF's surface enhance the binding of Au NPs with COFs to maintain the dispersity of NPs and their catalytic activity for long-term performance.?2?A 2D covalent organic framework O-COF containing ethoxylated chains was constructed by 1,3,5-trisformylbenzene and another terephthalic hydrazide derivatives.The O-COF was characterized by some fundamental physicochemical characterizations.The results show that O-COF is a 2D lamellar covalent organic framework with good crystallinity.Considering the good hydrophilicity of the long chain of ethoxylate in O-COF,we had measured its temperature sensitivity.It had been proved by temperature-dependent UV analysis that O-COF had good temperature sensitivity.To analyze the cytocompatibility of O-COF,we found that O-COF has good biocompatibility to mouse macrophages and mouse melanoma cells in the concentration range of 0-10?g/mL.The drug-loading performance of O-COF was tested.It was found that the drug loading of O-COF to doxorubicin hydrochloride was 4.5 wt%,and it had a sustained-release effect.?3?P-COF,thioctic acid?TA?and FeCl₃ were used to synthesize poly?TA-COF-Fe?to achieve the aim of enhancing poly?TA?materials by P-COF.The structure and stability of poly?TA-COF-Fe?were characterized by FT-IR and TGA,which proved that P-COF and disulfide group were successfully combined.The mechanical properties of poly?TA-COF-Fe?were explored by viscoelasticity tests and compression tests.Poly?TA-COF-Fe?had higher shear resistance than poly?TA-Fe?.The results of compression tests showed that the compression modulus of poly?TA-COF-Fe?is 87.0 kPa,which is much higher than the poly?TA-Fe?of 29.3 kPa,indicating that poly?TA-COF-Fe?had higher strength.It proved that P-COF is the material which had a reinforcement on poly?TA?materials.