The on-surface synthesis from predesigned organic precursors can yield graphene nanoribbons(GNRs)with atomically precise widths,edge terminations and dopants,which facilitate the tunning of their electronic structures...The on-surface synthesis from predesigned organic precursors can yield graphene nanoribbons(GNRs)with atomically precise widths,edge terminations and dopants,which facilitate the tunning of their electronic structures.Here,we report the synthesis of novel sulfur-doped cove-edged GNRs(S-CGNRs)on Au(111)from a specifically designed precursor containing thiophene rings.Scanning tunneling microscopy and non-contact atomic force microscopy measurements elucidate the formation of S-CGNRs through subsequent polymerization and cyclodehydrogenation,which further result in crosslinked branched structures.Scanning tunneling spectroscopy results reveal the conduction band minimum of the S-CGNR locates at 1.2 e V.First-principles calculations show that the S-CGNR possesses an energy bandgap of 1.17 e V,which is evidently smaller than that of an undoped cove-edged GNR(1.7 e V),suggesting effective tuning of the bandgap by introducing sulfur atoms.Further increasing the coverage of precursors close to a monolayer results in the formation of linear-shaped S-CGNRs.The fabrication of S-CGNRs provides one more candidate in the GNR toolbox and promotes the future applications of heteroatom-doped graphene nanostructures.展开更多
Construction of helicenes by inducing heteroatoms has regarded as an effective strategy to enhance the chiroptical properties.We report a facile synthesis of a multiple helicene based on four indoles with two electron...Construction of helicenes by inducing heteroatoms has regarded as an effective strategy to enhance the chiroptical properties.We report a facile synthesis of a multiple helicene based on four indoles with two electron-rich NBN-coved edges.The structure of the NBN-coved multiple helicene was confirmed by single-crystal X-ray diffraction analysis,revealing a twisted double[5]helicene motif with a saddle-shaped skeleton.This NBN-coved helicene showed strong green fluorescence with good photoluminescence quantum yield.Both theoretical calculations and experimental investigation have been exploited to probe the impact of electron-rich NBN units on aromaticity and photophysical properties of the helicene.展开更多
基金the National Natural Science Foundation of China(Grant Nos.51761135130,61888102,and 21774076)the National Key Research and Development Program of China(Grant Nos.2018YFA0305800 and 2019YFA0308500)+3 种基金the DFG Enhance Nano(Grant No.391979941)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant Nos.XDB30000000)the International Partnership Program of Chinese Academy of Sciences(Grant No.112111KYSB20160061)the K C Wong Education Foundation and the Program of Shanghai Academic Research Leader(Grant No.19XD1421700)。
文摘The on-surface synthesis from predesigned organic precursors can yield graphene nanoribbons(GNRs)with atomically precise widths,edge terminations and dopants,which facilitate the tunning of their electronic structures.Here,we report the synthesis of novel sulfur-doped cove-edged GNRs(S-CGNRs)on Au(111)from a specifically designed precursor containing thiophene rings.Scanning tunneling microscopy and non-contact atomic force microscopy measurements elucidate the formation of S-CGNRs through subsequent polymerization and cyclodehydrogenation,which further result in crosslinked branched structures.Scanning tunneling spectroscopy results reveal the conduction band minimum of the S-CGNR locates at 1.2 e V.First-principles calculations show that the S-CGNR possesses an energy bandgap of 1.17 e V,which is evidently smaller than that of an undoped cove-edged GNR(1.7 e V),suggesting effective tuning of the bandgap by introducing sulfur atoms.Further increasing the coverage of precursors close to a monolayer results in the formation of linear-shaped S-CGNRs.The fabrication of S-CGNRs provides one more candidate in the GNR toolbox and promotes the future applications of heteroatom-doped graphene nanostructures.
基金the National Natural Science Foundation of China(22001211)the Key Research and Development Program of Shaanxi Province(2023YBGY-454)+2 种基金Shaanxi Fundamental Science Research Project for Chemistry&Biology(Grant No.22JHQ015)for financial supportThis project is also supported by the Opening Project of Key Laboratory of Optoelectronic Chemical Materials and Devices of Ministry of Education,Jianghan University(No.JDGD-202208)the Fundamental Research Funds for the Central Universities.
文摘Construction of helicenes by inducing heteroatoms has regarded as an effective strategy to enhance the chiroptical properties.We report a facile synthesis of a multiple helicene based on four indoles with two electron-rich NBN-coved edges.The structure of the NBN-coved multiple helicene was confirmed by single-crystal X-ray diffraction analysis,revealing a twisted double[5]helicene motif with a saddle-shaped skeleton.This NBN-coved helicene showed strong green fluorescence with good photoluminescence quantum yield.Both theoretical calculations and experimental investigation have been exploited to probe the impact of electron-rich NBN units on aromaticity and photophysical properties of the helicene.
