Synthesis And Properties Of Carbon Nanorings Based On Hexabenzocoronene And Porphyrin Units

Since the report in 1991 by Dr.Sumio Iijima,carbon nanotubes(CNTs)have emerged as one of the most promising materials in the field of nanotechnology and materials science due to their remarkable mechanical,electronic,and optical properties.However,the low purity of CNTs by various reported methods has long been the bottleneck for fundamental studies and advanced applications of these materials.In recent years,the bottom-up approach has rapidly attracted much attention for its potential to synthesize CNTs with high purity by using template molecules.Since the first successful synthesis of cycloparaphenylene(CPP),researches on its preparation and properties have experienced rapid development.This present thesis conducted the studies on four kinds of nanoring structures as follows:1.A hexabenzocoronene(HBC)-containing cycloparaphenylene carbon nanoring,cyclo[12]-paraphenylene[2]-2,11-hexabenzocoronenylene,[12,2]CPHBC,was successfully synthesized by transition-metal-mediated cross-coupling reactions.A direct view of the molecular profile was obtained by scanning tunneling microscopy(STM).[12,2]CPHBC can be considered as an example of the longitudinal extension of the CPP scaffold and could be good precursors for the growth of CNTs.2.The large ?-extended carbon nanoring[4]CHBC was synthesized though a organoplatinum-mediated bottom-up approach.The electronic absorption and fluorescent behaviors of[4]CHBC revealed its unique optoelectronic properties.Furthermore,we have tentatively investigated the selective supramolecular host-guest interaction between[4]CHBC and C70,and their 1:1 complexation was confirmed.[4]CHBC could be useful for the bottom-up synthesis of structurally uniform carbon nanotubes.3.A large ?-extended porphyrin nanoring,[3]cyclo-5,15-porphyrinylene-4,4'-biphenylenes,[3]CPB has been synthesized by the organoplatinum-mediated bottom-up approach.Its structure and photophysical properties were determined by MS,NMR and UV-Vis absorption spectroscopy.This synthetic method would be useful for the construction of porphyrin-based macrocycles.4.The synthesis of a symmetrically multifunctionalized CPP,dodecamethoxy-[9]CPP has been achieved through Ni-mediated macrocyclization and subsequent reductive aromatization.Our strategy is to introduce the functional groups at an early stage by preparing building precursors bearing methoxy groups.Dodecamethoxy-[9]CPP exhibited different optical properties compared with[9]CPP.In addition,the supramolecular interactions between dodecamethoxy-[9]CPP and guest molecules was tentatively investigated.This multifunctionalized CPP structure can provide a suitable platform for subsequent synthetic manipulations or be transformed into other functional groups,which will be valuable for the construction of other interesting and unprecedented nanocarbon structures.