Preparation Of Immobilized Cyclic Metal Ruthenium Catalyst And Its Application In Dehydrogenation Of Indoline

Cyclometalated Ir（Ⅲ） complexes, or iridicycles, show efficient catalytic performance as homogeneous catalysts in a variety of catalytic systems. While, similarly to the complexes in other homogenous catalysis systems, the iridicycles have not been applied in large-scale due to the expensive iridium as well as the difficulty to recycle such catalysts, which also lead to heavy waste of noble resources and the high cost in their application. Therefore, it is highly expected to find an effective way to recycle the iridicycles, which will definitely promote the exploration of this facile complex as a catalyst and its application. The main contents and the primary results in this thesis are presented as follows:（1） Preparation and characterization of targrted immobilized iridicycles.Three novel iridicycles were synthesized as the potential active centers of the immobilized Ir catalyst. A pyrene tag was intentionally introduced into the iridicycle and used as an anchoring site to immobilize the iridicycle onto the selected support of multi-walls carbon nanotubes （MWCNTs） via π-π stacking interactions. The conditions of immobilization, including the outer diameter of MWCNTs, the solvent, and the iridicycle loadings were respectively investigated to successfully achieve the valuable immobilization of the iridicycle. Furthermore, the iridicycles and immobilized iridicycles were well characterized by NMR, XPS and fluorescence spectroscopy. It is found that the optimized immobilization conditions were THF/H2O （VH2O:VTHF= 2:1） as the solvent, MWCNTs （OD< 8 nm） as the support, and a 0.58 mmol·g^-1 as the maximum catalyst loading, under which the targeted immobilized iridicycle is expected to be successfully prepared with a high activity, high stability and well recyclability.（2） Evaluation and application of the immobilized iridicycle catalystThe catalytic dehydrogenation （CDH） of indoline was selected as a model reaction. The scope of suitable subtrates for the immobilized iridicycle was also investigated. Under the optimized conditions, the activity of the immobilized iridicycle catalyst was definitely evaluated by comparing the yield of the above mentioned CDH reaction. In addition, the leching of iridicycle （active center） from MWCNTs was detected via ICP-MS and fluorescence spectroscopy so as to evaluate the recyclability and stability of the immobilized iridicycle catalyst. The immobilized iridicycle catalyst showed good catalytic performances for a wide range of indolines with both electron-withdrawing groups and electron-donating groups. It is also found that the immobilized iridicycle could be recycled for at least seven times without obvious loss of the Ir-active centre （less than 7% in all runs） and noticeable decrease in the yield of the targeted product （from 100% to approximately 90%） under the optimized reaction conditions. The optimized conditions are the reaction time of 12 h, under air atmosphere, and the iridicycle loading of 0.29 mmol·g^-1.It is highly expected that the proposed immobilization stratergy of iridicycle will lay a strong foundation for the large-scale application of the iridicycles, and also provide valuable references to the further research and application of other important （cyclo）metalic complexes in promising catalytic systems.