Syntheses And Performance Of Nanocone And Buckybowl Compounds Based On Corannulene

Geodesic polycyclic aromatic compounds,nanocones or buckybowls,are considered to be another group of key materials in addition to C60 and carbon nanotubes in curved ?-conjugated carbon system.The chemistry of buckybowls have been extensively studied after the reports on the short synthesis of corannulene using gas-phase method(flash vacuum pyrolysis,FVP)by Scott and Siegel et al.in 1990s.corannulene,the smallest unit of buckybowl and nanocone with the cone apex angle equal to 112.9°,is a vital synthon to construct larger buckybowls and nanocones,once extra six-membered rings or five-membered rings were introduced respectively.These compounds are important because of their excellent physicochemical properties,which are generated by unique structure and abundant electrons as well as their non-uniform distribution within the curved surface.And they have extensive application prospects in scanning probes,field emitters,molecular recognition,metal complexation,supramolecular assembly,electronic conductivity,and so on.Highly strained ?-bowls or ?-cones are still challenging targets in synthetic organic chemistry.There are various non-classical chemical-physical techniques car be used to produce carbon nanocones(CNCs),such as chemical vapor deposition(CVD),laser ablation,and pyrolysis of organic compound.However,to date the related research progress of CNCs is much slower compared with that of CNTs.One main reason for this is the lack of effective preparation methods for CNCs.Only tiny amount of products are CNCs,most of which are nanographenes,nano tubes and nanoparticles based on the current synthetic technique.As for buckybowls,flash vacuum pyrolysis has proven to be an effective tool for forming curved bonds.On the other hand,a nonpyrolytic synthetic strategy has been strongly required for the elaborate synthesis of this class of molecules because the reaction conditions of FVP are quiet severe and an employable functional group is limited.Recently,scientists reported the synthesis of a series of highly strained bowls using Mizoroki-Heck reactions or[(2+2)+2]cycloaddition as a key step.Both of them are requiring special functional groups,therefore,it is important to seek suitable C-C coupling between sp2 C-H and sp2 C-H for constructing highly strained ?-bowls.We intend to introduce aromatic compounds containing six-membered rings or five-membered rings previously in precursors,and then,Scholl reaction is applied to synthesis larger nanocones or buckybowls.The work of this thesis includes the following three parts:1.Corannulene and its halide,as well as boride,were synthesized according to references.2.The synthsis of penta-mesitylnaphthylcorannulene from sym-pentakis(Bpin)-corannulene using 5-fold intermolecular Suzuki reactions,and then,10-fold intramolecular Scholl reactions were applied in ring closure step to form the nanocone C70H15R5(R=mesityl).To best of our knowledge,it is the largest bowls and the only well defined cones until now.The final product was characterized by Mass spectroscopy,NMR and X-ray single crystal diffraction studies.We also studied its optical and electrical properties by UV-vis and cyclic voltammetry,respectively.Furthermore,computational studies based on B3LYP/6-31 G(d,p)was applied to calculate its HOMO,LUMO,POAV and reverse behaviors etc.With the development of homodesmic reaction and NICS,which were used for calculating the energy difference and aromaticity,respectively.We are facilitate to discuss the regioselectivity.3.We also tried to synthesized azabuckybowl by repetitive Scholl reactions from sym-penta-heteroaryl-corannulene,which was constructed by using 5-fold nucleophilic substitutions.However,we were failure to get ?-extended azabuckybowl through this strategy even if many attempts have been done.