Visible-Light-Driven Rh-Catalyzed Synthesis Of Benzocarbazole Derivatives And Their Fluorescence Properties

As one crucial member of the carbazole compounds,benzocarbazoles are widely present in natural products and bioactive molecules.Specifically,owing to its excellent fluorescence emission,benzocarbazole is always the core skeleton of organic fluorescence materials.The last decade has witnessed the significant progress of their synthesis in multiple dimensions,and various pioneer works have been reported.However,in terms of reaction efficiency and selectivity,previous synthetic methods are still facing challenges.The merger of transition metal catalysis and photocatalysis,which can promote the reaction occurring under very mild reaction conditions with the aid of light irradiation,has recently emerged as a versatile platform for developing green,highly enabling synthetic methodologies for valuable organic molecules.With the combination of Rh catalysis and photoredox catalysis as the research core,in this thesis,we have developed a new method for the synthesis of benzocarbazole derivatives via visible-light-driven Rh-catalyzed C-H annulation,and a wide range of benzocarbazole derivatives have been successfully synthesized.Furthermore,the mechanism of this synergistic catalytic reaction and the fluorescence performance of synthesized benzocarbazole derivatives were studied.The main results of them are as follows:（1）A new method for the synthesis benzocarbazole derivatives via visible-light-driven Rhcatalyzed C-H annulation has been developed.In this protocol,Rh（III）complex was employed as the transition-metal catalyst and Eosin-Y was employed as the photosensitizer,.With the blue LED irradiation,a serial of benzocarbazole derivatives have been synthesized from N-pyridine protected aromatic amines and bicicyclic alkenes under very mild reation conditions.This reaction is simple,efficient and well tolerated by multiple substituents.In addition,it could be easily scaleup in gram scale,exhibiting promising further application potential.（2）Based on the characteristic luminescence of benzocarbazoles,several benzocarbazoles with different substituents and conjugation length were synthesized.Then,to obtain the fluorescence performance of them,the UV-Vis spectra and fluorescence emission spectra for them were recorded.And the maximum absorbance wavelength,maximum excitation wavelength,maximum emission wavelength,the fluorescence quantum yields and other key fluorescence parameters for the target compounds were obtained and calculated.Most of the selected compounds were found to emit strong blue fluorescence with peaks located at 410-500 nm,and their fluorescence quantum yields ranges from 12% to 70%,implying that they are all suitable units to assemble excellent blue-light-emitting materials.