The Synthetic Exploration Of Perphenyl-substituted Thiophene-acetylene Macrocycle And Carboncone[1,4]

Nano-carbon molecules with full conjugate and hollow structure(macrocyclic structure/carbon nanobelts/carboncones,etc.)have good application prospects in gas adsorption,host-guest chemistry,molecular devices and new three-dimensional functional materials due to their unique photophysical and electrochemical properties.Among them,the precise chemical synthesis of the two types of molecules,carbon nanobelts and carboncones,is considered to be a very challenging research topic in the field of nano-carbon molecular synthesis chemistry.For the synthesis of carbon nanobelts,we envisage introducing phenyl as a substituent to obtain the fully phenyl-substituted thiophene-acetylene macrocycle.Then,all the phenyl groups are sequentially connected through the subsequent intramolecular cyclization dehydrogenation reaction,so as to synthesize the conjugated thia nanobelt with a double circinal hollow structure.The unique optoelectronic properties of this molecule are expected to be applied in the fields of metal coordination recognition,host-guest self-assembly,and organic optoelectronic materials.In this thesis,according to the designed synthetic route,after seven steps of conventional organic synthesis,the perphenyl-substituted[5]thiophene-acetylene long-chain molecule was prepared,which behaves strong absorption and fluorescence emission properties.Unfortunately,due to the long reaction steps of the single route,the difficulty of separation and purification,and the excessive number of sites for the aldehylation reaction,the macrocyclic thiophene substituted with perphenyl and subsequent thia nanobelts was not successfully obtained in the end.Therefore,we have only made some progress in the synthesis of thia nanobelt molecules.Conical carbon is a new type of sp2 hybrid carbon allotrope except fullerene,carbon nanotube and graphene.The unique cone shape,hollow structure and different cone angles,cone heights and defects endow carbon nanocones with a variety of interesting physical and chemical properties,which are expected to be used as field emission sources,scanning probes and sensors,etc.However,the carbon nanocones prepared by traditional physical-chemical synthesis techniques are mainly multi-walled,and contain graphene,carbon nanotubes,carbon black,which makes it difficult to separate and purify.Therefore,emerging bottom-up organic synthesis methods for precise single-walled carbon cone molecules is particularly important.Based on the molecular synthesis ideas of carbon cone[1,2]reported in the literature,this paper proposes a synthesis route for carbon cone[1,4]molecules with larger cone height and π system.First,a sufficient amount of corannulene is prepared and used in subsequent borylation to yield 1,3,5,7,9-pentaborate corannulene as a synthon,and simultaneously we prepared a small molecule fragment-binaphthyl derivative for external connection.Five binaphthyl derivatives were linked with corannulene to produce the carboncone[1,4]precursor by the Suzuki reaction,and subsequent ring-closure attempts were carried out.The results of the intramolecular ring-closing reaction of the precursor molecule showed that only 15 new carbon-carbon bonds were formed,but the realization of the carbon cone[1,4]molecule requires the formation of 30 new carbon-carbon bonds.In order to improve the solubility and reactivity of the ring-closure precursor to successfully prepare carboncone[1,4]molecules,we proposed an improved scheme for the synthesis of small molecule fragments by introducing electron-rich methoxy group and tert-butyl which helps to improve solubility.The perphenyl-substituted macrocyclic thiophene(including the thia nanobelt after the ring closure)and the carbon cone[1,4]molecule have a special conformational internal cavity and a π-conjugated structure.The synthesis of the two provides research ideas for the bottom-up directional preparation of carbon nanotubes and other new organic functional materials.