Study On The Mechanism Of Cyclodextrin Metal-Organic Framework Loading Sulfur Hexafluoride

Sulfur Hexafluoride?SF₆?is a colorless,odorless,non-toxic,non-corrosive,non-flammable gas under normal temperature and pressure,SF₆ can be prepared into lipid microbubbles with proteins,polymers or lipid shells,which can significantly improve the efficacy of contrast-enhanced ultrasound.The?-cyclodextrin metal organic framework??-CD-MOF?is a novel highly porous material,which reassembles the circular structure of the cyclodextrin planarization to form a three-dimensional network skeleton with high porosity and high specific surface area so that it can be used for gas adsorption and storage.This research mainly used?-CD-MOF loading SF₆,in order to prepare a new type of contrast agent,to improve the ultrasound imaging effect in animals.The ultrasound imaging effect of the sample on the SD rat was initially tried.After injecting the sample,the signal inside and outside the blood vessel was different,and the intravascular signal showed an increasing trend.A quantitative nuclear magnetic method was established with fluconazole as the reference and trifluoroacetic acid as the internal standard to determine the content of SF₆.The SF₆ content in?-CD-MOF was 2.67±0.46 wt%.Molecular simulation and ¹⁹F-NMR spectra were combined to study the exist state of SF₆ in?-CD-MOF.At the same time,influence of the structure after grinding on carrier gas and the change of relative content under normal pressure were investigated.After grinding the regular crystal of?-CD-MOF was disappeared and the gas loading capacity was lost.The sample of?-CD-MOF loaded SF₆ was stored at 0.1 MPa for 10days,the relative content was 74.7%.The combination of various methods shows that SF₆preferred to stay in the cavity of?-CD-MOF cubes rather than in the?-CD molecular pairs,which was a non-chemical adsorptive process.In conclusion,this study mainly established the qNMR method and molecular simulation to study the mechanism of SF₆ loading.