Chiral Functionalization Of Carbon Nanotubes And Its Application In The Field Of Chiral Separation

Studies on carbon nanotubes (CNT) become a hot topic in the world due to the unique one-dimensional tubular structure and subtle physical and chemical properties of CNT. Compared with other area, the study in the functionalization of CNT has been developed quickly, but there was no paper reported on the application of CNT in chiral separation. In the present dissertation, this new material was functionalized with chiral reagents that were covalent bonded on the tubes and caps. The application in chiral separation and recognition were studied firstly. This work may be of great signification for applying nano-material further. The main achievements obtained in this research include:1. carboxyl of multi-wall carbon nanotubes(MWNT)The MWNTs was oxidized with mixture of concentrated sulfuric acid and nitric acid. It was showed that the degree of oxidation and truncation was different even using the same acids as oxidant. The difference was mainly caused by the preparation methods of MWNT. According to the properties of the MWNT used in this study, the relation between the degree of carboxyl and oxidation time or acids strength was systematically studied. Usually the MWNT was ultrasonic in different acids for 3 to 5 hours, and the proper oxidized carboxyl MWNT can be obtained.2. Amino acids functionalized MWNT were prepared, the IR spectra and Electrochemical characteristic were also studied.L-tryptophan and L-tyrosine were used as chiral reagents on the covalent functionalization of MWNT. The product was characterized with SEM, FT-IR Spectrum and Electrochemical method. The direct electron transfer of functionalized MWNT was investigated at graphite electrode. It was applied to the determination of tryptophan enantiomers with this modified electrode. There were some differences on the current and potential peak between the enantiomers.3. 3 -cyclodextrin functionalized MWNT was synthesized. Its behavior on the solid extraction of tryptophan isomer was simply investigated.β -cyclodextrin was covalent bonded on the MWNT as chiral reagent. The product was characterized with FT-IR Spectrum and Electrochemical method. It was proved thatthe degree of fiinctionalization was low, and it is difficulty to separate the product and carboxyl MWNT. Good result was obtained when it was used as solid extractive solvent to separate the tryptophan isomers.