Synthesis And Properties Of Post-functionalized Cobalt Corroles Based On Suzuki Coupling

Corrole,one of the important porphyrin derivative,has a meso-position carbon condensation to form a directly linked carbon-carbon single bond.Since corrole has the smaller inner cavity and three N-H protons,so that the corrole can efficiently stabilize various metal ions at higher valence states.Thus,the uniquely electrochemical and optical properties of corroles have been widely attracted by researchers in various research field.In addition,the synthesis of corroles is generally proceeded through the reaction between aryl-aldehydes and pyrrole through acid catalyzed system.Unfortunately,the progress of synthetic chemistry of corrle is still lack due to most of aryl-aldehydes are not commercially available.Thus,we need try to find out new methods to synthesize corroles,such as post-functionalization.On the other hand,Suzuki coupling reaction is one of the important C-C bond formation reaction during organic synthesis by using halogenated aromatic hydrocarbons and arylboronic acids as raw materials.Therefore,the modification of the molecular structure of corroles by the Suzuki-coupling reaction can provide a new insight of the synthetic chemistry of corroles.More interestingly,metallocorroles can be applied as highly efficient electrochemical catalysts in various energy conversion processes,such as electrochemically catalyzed hydrogen evolutions?HERs?,oxygen reduction reactions?ORRs?and even oxygen evolution reactions?OERs?.Thus,in this master thesis,we will design,synthesis of a new series of metallo-corrles through Suzuki coupling method and investigate the electrochemically catalyzed energy conversion.Also,the relationship among molecular structure,electronic structure and catalytic behaviors will be detailed described.In the first section,5,10,15-tris?p-bromophenyl?Co?III?corrole was successfully prepared as the key precursor,and six different kinds of meso-triaryl-Co?III?corroles were obtained through Suzuki coupling by using six different aryl-boronic acids.In the second section,when 5,10,15-tris?m-bromophenyl?Co?III?corrole was used instead,five more meso-triaryl-Co?III?corroles were prepared and isolated,as well.The reaction changes the position of the Suzuki coupling reaction by changing the position of substitution of bromine,thereby changing the position of the aryl substituent on the corrole ring.Then,the electronic structure of these Co?III?corroles were investigated by spectroscopic analysis including ultraviolet visible spectroscopy?UV-vis?,mass spectrometry?MS?,nuclear magnetic resonance spectroscopy?¹H NMR?,infrared spectroscopy?IR?,and electrochemical measurements such as CVs,DPVs.Furthermore,the electrochemically catalytic behaviors of oxygen evolution,oxygen reduction as well as hydrogen evolution in graphene supported system in aqueous media,and all electrochemically catalytic behaviors were well modulated by introduction various type and position of meso-substituents.In addition to regulating the substitution position of bromine to study the effects of Suzuki coupling reaction on the corrole compounds,the influence of the substitution number of bromine on the corrole compounds was also studied.In the third section,low symmetric corroles containing zero-to-three bromophenyl positions?n=1,2,3?were used as the key precursors,and introduce phenyl and nitrophenyl groups by Suzuki coupling reaction.Finally,six different structural features of Co?III?corroles through Suzuki coupling were systhesized.Then,the electronic structure of these Co?III?corroles were investigated by spectroscopic analysis including ultraviolet visible spectroscopy?UV-vis?,nuclear magnetic resonance spectroscopy?¹H NMR?,infrared spectroscopy?IR?,and electrochemical measure-ments such as CVs,DPVs.Furthermore,the electrochemically catalytic behaviors of oxygen evolution,oxygen reduction as well as hydrogen evolution in graphene supported system in aqueous media,and all electrochemically catalytic behaviors were well modulated by introduction various type and number of meso-substituents.All these results demonstrated the introduction of different meso-substituents through Suzuki-coupling reactions are the effective methods for the preparation highly efficient molecular catalysts in energy conversion reactions.Base on these advantages of Co?III?corroles,we also synthesized four different A₃-type Co?III?corroles containing o-functionalized meso-substituents.In addition to the different substituents,we explored the effects of the steric hindrance of the ortho-substituent on the corrole ring.The electronic structure was investigated by spectroscopy and electrochemistry,and the electrochemically catalyzed oxygen reduction reactions could also be modulated.