Synthesis Of A Well-defined,N-doped And Saddle-shaped Nanographene

In 2013,Scott and Itami et al.reported the synthesis of a saddle-shaped nanographene molecule which represents a new class of nano carbon molecule following spherical fullerenes,tubular carbon nanotubes,and planar graphene.The defects of the non-hexagonal carbon ring structure not only severely distort the type of nanocarbon molecules,but also exhibit different physical,optical,and electrical properties from planar nanographene molecules(hexagonal honeycomb structures).Electrochemical experiments show that saddle-shaped nanographene and planar nanographene are both easily oxidized,but curled graphene is more difficult to be reduced.According to previous reports,different nano-graphene molecules or bowl-shaped corannulene doped with different heteroatoms can change their electronic properties,such as band gap and electrocatalytic activity.It is expected that the electronic properties,physical properties,and optical properties will change great after the heteroatom was doped into saddle-shaped nanographene.However,there has been no report on the heteroatom doped saddle-shaped nanographene so far.In this dissertation,a bowl-shaped molecular corannulene(C20H10)was used as a starting material to efficiently synthesize a multi-nitrogen-doped saddle-shaped nanographene molecule with a determined structure by a 5-step organic reaction.The main content of this paper includes the following three aspects:1.Raw material synthesis of N-doped and saddle-shaped nanographene.In this paper,dozens of grams corannulene(C20H10)are synthesized as the starting material after eight synthesis steps referring to Siegel et al.Then,1,3,5,7,9-penta(boryl ester)corannulene was synthesized referring to Scott’s method.2.Synthesis of N-doped and saddle-shaped nanographeneA series of 1,3,5,7,9-penta(phenyl)corannulene was synthesized from 1,3,5,7,9-penta(boryl ester)corannulene by Suzuki cross-coupling reaction.Derivatives which ester-substituted can form 1,3,5,7,9-penta(4-butylformyl)phenyl-2,4,6,8,10-pentachlorocorannulene under the chlorination conditions of iodine chloride,and then the pyrrole anion attacks the C-Cl bond on the chlorinated molecule as a nucleophile,performing a nucleophilic substitution reaction 1,3,5,7,9-penta(4-butyl formate)phenyl-2,4,6,8,10-pyrrolylcorannulene,and finally the oxidative ring closure by the Scholl reaction results in a structurally defined polynitrogen-doped saddle-shaped nanographene molecule.The structure of the compound was speculated by nuclear magnetic resonance spectroscopy and carbon spectroscopy.In subsequent experiments,we will try to cultivate a single crystal and determine its structure by X-ray single crystal diffraction.It is worth mentioning that due to the introduction of a long-chain substituent(butyl formate)at the para-position of the phenyl group,the problem of poor solubility of most aromatics derivatives has been solved,enabling them to be purified through silica column chromatography.The polyatomic nitrogen-doped and saddle-shaped nanographene molecule may have potential for hydrogen storage,supramolecular self-assembly,supercapacitors,or perovskite solar cells as hole transport materials due to the introduction of electron-rich N atoms.3.The optimization of the synthesis method of decachlorocorannuleneIn addition,we refer to Scott and Siegel’s method for synthesizing dechlorocorannulene and Tan’s method for preparing the graphene-perchlorinated fragment and improve it.The new method increases the yield of decachlorocorannulene from 60%to 96%without the harsh reaction condition that require anhydrous and oxygen-free.