Study On The Pyrolysis Reaction Of Carbon Monoxide-releasing Molecules From Chromium Carbonyls

The transition metal carbonyl complex as Carbon monoxide releasing molecules(CORMs)can release CO under the action of light induction,enzyme induction and oxidation induction,etc.However,the i-CORM with heavy metal center and the residual non carbonyl coordination formed by these CORMs after release will cause irreversible damage to the body cells.In order to overcome the above problems and realize the precise control of the release kinetic of CORMs,this paper adopts a new CO induction method-pyrolysis induced CO release.A series of thermosensitive CO release molecules(T-CORMs)were prepared by using chromium metal carbonyl complexes with five carbonyl ligands as the lead structure and different kinds of quaternary ammonium salts and amino acid esters as ligands,and the pyrolysis behavior,CO release mechanism and performance were studied.The research content of this paper is summarized in the following four parts:1.Three kinds of pentacarbonyl chromium compounds were prepared,which are halogenated quaternary ammonium salt,Fischer carbene salt and Fischer neutral type.All of the compounds were characterized by IR,NMR and elemental analysis.Moreover,the crystal structures of the obtained compounds 1b,3c and 5c were analyzed by single crystal X-ray diffraction.2.The thermal sensitivity and thermogravimetry of the above three types compounds in nitrogen atmosphere were studied by TG-DSC,and the thermokinetic parameters of the compounds were calculated by Kissinger method and Ozawa method,respectively.The results indicated that the thermal sensitivity,thermogravimetry process and thermal decomposition kinetic parameters of the compounds are determined by the spatial structure of the compounds,the relative binding strength of M-L and M-CO bonds and their coordination.The thermal weightlessness behavior was also tested by DTA and compared with the weightlessness history under an inert atmosphere,and the results showed that air oxygen has a greate influence on the thermal decomposition process of the compounds.3.TG-IR-GCMS instrument was used to monitor the thermal decomposition gas products of the three compounds 3c,4b,and 5c in real time,the results showed that the three kinds of compounds would release CO gas at 103 ℃,90℃ and 109℃respectively;DFT was used to accurately calculate the bond energy of the M-CO bond and the M-X bond in the 3c structure and the results showed that the bond energy of M-X is less than the bond energy of M-CO;the solid products of 3c compound are further studied by IR,XPS,SEM-EDS and elemental analysis,the results showed that the solid product is basically free of C element,the main component is chromium oxide;through the speculation of the decomposition mechanism of 3c,it is found that the compound can release pure CO gas in a temperature range after the decomposition.4.The process of CO release from the pyrolysis of three kinds of T-CORM at different temperatures was monitored by the traditional myoglobin method.The results revealed that the three types of compounds can achieve pyrolysis of CO release,and the lc compound can released CO gas at 60℃.The thermogravimetric method was used to test the thermostatic weightlessness of the compounds at different temperatures.It was found that the CO release and diffusion kinetics curve has a good match with the thermostatic weightlessness curve.In summary,the way of CO release induced by pyrolysis in this paper,combined with the ligand regulation strategy to select ligands in the chromium pentacarbonyl release molecules,can realize the regulation of the T-CORM pyrolysis CO release process,and achieve the purpose of safe,controllable and accurate CO release.