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
Nanographenes(NGs)can be embedded with predesigned dopants or nonhexagonal rings to tailor the electronic properties and provide ideal platforms to study the unique physical and chemical properties.Here,we report the ...Nanographenes(NGs)can be embedded with predesigned dopants or nonhexagonal rings to tailor the electronic properties and provide ideal platforms to study the unique physical and chemical properties.Here,we report the on-surface synthesis of NBN-doped NG embedded with five-and seven-membered rings(NBN-575-NG)on Au(111)from a oligophenylene precursor preinstalled with a NBN unit and a heptagonal ring.Scanning tunneling microscopy and non-contact atomic force microscopy images elucidate the intramolecular cyclodehydrogenation and the existence of the five-and seven-membered rings.Scanning tunneling spectroscopy spectra reveal that the NBN-575-NG is a semiconductor,which agrees with the density functional theory calculation results on a freestanding NBN-575-NG with the same structure.This work provides a feasible approach for the on-surface synthesis of novel NGs containing non-hexagonal rings.展开更多
Oil dispersible suspension concentrates are safe,green,and environmentally friendly formulations.Problems such as layering,pasting,and bottoming are frequently encountered during the production,storage,and transportat...Oil dispersible suspension concentrates are safe,green,and environmentally friendly formulations.Problems such as layering,pasting,and bottoming are frequently encountered during the production,storage,and transportation process.Polyisobutylene succinimide functions as a dispersant and exhibits great potential to improve the physical stability of the oil dispersible suspension concentrate.From a microscopic perspective,the sorption characteristics of the polyisobutylene succinimide dispersant T151 on penoxsulam particle surfaces were comprehensively evaluated with XPS,FTIR,and SEM.The T151 adsorption procedure complied with a pseudo-second-order kinetic adsorption model,and it was a kind of physical sorption with an Ea of 22.57 kJ⋅mol^(−1).The T151 sorption model was consistent with the Langmuir isotherm.The adsorption process was spontaneous and followed by an entropy increase.TheΔH^(θ)of dispersant T151 on the surface of penoxsulam particles was 31.59 kJ⋅mol^(−1).The adsorption procedure was endothermic,and the primary force was hydrogen bonding.The XPS results showed that the F and S electronic peaks at the penoxsulam interface decreased,and that the C electronic peak increased significantly after the adsorption of dispersant T151,indicating the adsorption on the surface of penoxsulam particles.The results of this study provide a vital theoretical basis for the application of polyisobutylene succinimide dispersants in oil dispersible suspension systems.展开更多
The precise synthesis of helicenes with topologically defined length and specific heteroatomic perturbation in the screw-like conjugated skeletons plays an emerging role in the manipulation of chiral materials.Facile,...The precise synthesis of helicenes with topologically defined length and specific heteroatomic perturbation in the screw-like conjugated skeletons plays an emerging role in the manipulation of chiral materials.Facile,selective,and programmable routes to helicenes or heterohelicenes are highly desirable yet challenging for structure-chiroptical property relationship studies.Herein,we report the synthesis and characterization of NBN-doped helicenes with boron atoms in the inner rims,enabled by the highly regioselective one-pot borylation of rationally designed precursors with,namely,fold-in or pan-out manner.The incorporation of nonbonded boron and nitrogen atoms resulted in narrow-band emission and improved optical properties for the single-stranded carbon helix.In addition,numbers and arrangement modes of fused six-membered rings have distinct effects on configurational stability and chiroptical properties,revealing that BN-[6]H with strong circular dichroism is a promising candidate for chiral sensors.The combination of experimental and theoretical studies on these helical structures might provide insights into the design of helically chiral small-molecule-based sensors or emitters.展开更多
Main observation and conclusion In this paper,two novel donor-acceptor(D-A)macrocyclic compounds 5 and 7 were successfully synthesized by post-functionalization of a planar dimer macrocycle(1)and a highly twisted trim...Main observation and conclusion In this paper,two novel donor-acceptor(D-A)macrocyclic compounds 5 and 7 were successfully synthesized by post-functionalization of a planar dimer macrocycle(1)and a highly twisted trimer macrocycle(2),respectively,via controllable oxidation of methoxy groups and condensation between diketones and phenylenediamine in succession.Compared with unembellished 9,10-dimethoxyphenanthrene,the resultant dibenzo[a,c]phenazine motif is electron-deficient rather than electron-rich,yielding two D-Aπ-conjugated macrocycles with more contractive energy gaps.Density functional theory(DFT)calculations further support the unequivocal evidence of the D-A properties of macrocycles 5 and 7.The difference of their photophysical properties was investigated by the aid of ultraviolet-visible absorption and fluorescence spectrophotometers.Furthermore,the stacking patterns of 7 and its contrastπ-conjugated macrocycle trimer(2)were compared via the analysis of X-ray single crystal,in which the electron-deficient dibenzo[a,c]phenazine unit provides extra interaction sites,resulting in orderly arrangement of 7 in the solid state.展开更多
Zigzag graphene nanoribbons(ZGNRs)with spin-polarized edge states have potential applications in carbon-based spintronics.The electronic structure of ZGNRs can be effectively tuned by different widths or dopants,which...Zigzag graphene nanoribbons(ZGNRs)with spin-polarized edge states have potential applications in carbon-based spintronics.The electronic structure of ZGNRs can be effectively tuned by different widths or dopants,which requires delicately designed monomers.Here,we report the successful synthesis of ZGNR with a width of eight carbon zigzag lines and nitrogen-boronnitrogen(NBN)motifs decorated along the zigzag edges(NBN-8-ZGNR)on Au(111)surface,which starts from a specially designed U-shaped monomer with preinstalled NBN units at the zigzag edge.Chemical-bond-resolved non-contact atomic force microscopy(nc-AFM)imaging confirms the zigzag-terminated edges and the existence of NBN dopants.The electronic states distributed along the zigzag edges have been revealed after a silicon-layer intercalation at the interface of NBN-8-ZGNR and Au(111).Our work enriches the ZGNR family with a new dopant and larger width,which provides more candidates for future carbonbased nanoelectronic and spintronic applications.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(Grant Nos.51761135130 and 61888102)the National Key R&D Program of China(Grant Nos.2018YFA0305800 and 2019YFA0308500)+3 种基金DFG EnhanceNano(Grant No.391979941)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB30000000)the International Partnership Program of Chinese Academy of Sciences(Grant NO.112111KYSB20160061)the K.C.Wong Education Foundation.Part of the research was performed in the Key Laboratory of Vacuum Physics,Chinese Academy of Sciences.Computational resources were provided by the National Supercomputing Center in Tianjin Municipality,China.
文摘Nanographenes(NGs)can be embedded with predesigned dopants or nonhexagonal rings to tailor the electronic properties and provide ideal platforms to study the unique physical and chemical properties.Here,we report the on-surface synthesis of NBN-doped NG embedded with five-and seven-membered rings(NBN-575-NG)on Au(111)from a oligophenylene precursor preinstalled with a NBN unit and a heptagonal ring.Scanning tunneling microscopy and non-contact atomic force microscopy images elucidate the intramolecular cyclodehydrogenation and the existence of the five-and seven-membered rings.Scanning tunneling spectroscopy spectra reveal that the NBN-575-NG is a semiconductor,which agrees with the density functional theory calculation results on a freestanding NBN-575-NG with the same structure.This work provides a feasible approach for the on-surface synthesis of novel NGs containing non-hexagonal rings.
基金This work was funded by the Foundation(No.LJ2020030)from the Project of the Education Department of Liaoning Province,China.
文摘Oil dispersible suspension concentrates are safe,green,and environmentally friendly formulations.Problems such as layering,pasting,and bottoming are frequently encountered during the production,storage,and transportation process.Polyisobutylene succinimide functions as a dispersant and exhibits great potential to improve the physical stability of the oil dispersible suspension concentrate.From a microscopic perspective,the sorption characteristics of the polyisobutylene succinimide dispersant T151 on penoxsulam particle surfaces were comprehensively evaluated with XPS,FTIR,and SEM.The T151 adsorption procedure complied with a pseudo-second-order kinetic adsorption model,and it was a kind of physical sorption with an Ea of 22.57 kJ⋅mol^(−1).The T151 sorption model was consistent with the Langmuir isotherm.The adsorption process was spontaneous and followed by an entropy increase.TheΔH^(θ)of dispersant T151 on the surface of penoxsulam particles was 31.59 kJ⋅mol^(−1).The adsorption procedure was endothermic,and the primary force was hydrogen bonding.The XPS results showed that the F and S electronic peaks at the penoxsulam interface decreased,and that the C electronic peak increased significantly after the adsorption of dispersant T151,indicating the adsorption on the surface of penoxsulam particles.The results of this study provide a vital theoretical basis for the application of polyisobutylene succinimide dispersants in oil dispersible suspension systems.
基金supported by the Hong Kong Research Grants Council(27301720,17304021)National Natural Science Foundation of China(22122114,22122503,21790361).
文摘The precise synthesis of helicenes with topologically defined length and specific heteroatomic perturbation in the screw-like conjugated skeletons plays an emerging role in the manipulation of chiral materials.Facile,selective,and programmable routes to helicenes or heterohelicenes are highly desirable yet challenging for structure-chiroptical property relationship studies.Herein,we report the synthesis and characterization of NBN-doped helicenes with boron atoms in the inner rims,enabled by the highly regioselective one-pot borylation of rationally designed precursors with,namely,fold-in or pan-out manner.The incorporation of nonbonded boron and nitrogen atoms resulted in narrow-band emission and improved optical properties for the single-stranded carbon helix.In addition,numbers and arrangement modes of fused six-membered rings have distinct effects on configurational stability and chiroptical properties,revealing that BN-[6]H with strong circular dichroism is a promising candidate for chiral sensors.The combination of experimental and theoretical studies on these helical structures might provide insights into the design of helically chiral small-molecule-based sensors or emitters.
基金supported by the Hong Kong Research Grants Council(HKU 27301720).J.L.is grateful for the funding support from ITC to the S.K.L.We thank the UGC funding administered by The University of Hong Kong(HKU)supporting the Time-of-Flight Mass Spectrometry Facilities under the Support for Interdisciplinary Research in Chemical Science,and HKU University Development Fund for funding the X-Ray Diffractometer Facilities.We acknowledge the computer cluster(HPC2015)HKU for generous allocations of compute resources.
文摘Main observation and conclusion In this paper,two novel donor-acceptor(D-A)macrocyclic compounds 5 and 7 were successfully synthesized by post-functionalization of a planar dimer macrocycle(1)and a highly twisted trimer macrocycle(2),respectively,via controllable oxidation of methoxy groups and condensation between diketones and phenylenediamine in succession.Compared with unembellished 9,10-dimethoxyphenanthrene,the resultant dibenzo[a,c]phenazine motif is electron-deficient rather than electron-rich,yielding two D-Aπ-conjugated macrocycles with more contractive energy gaps.Density functional theory(DFT)calculations further support the unequivocal evidence of the D-A properties of macrocycles 5 and 7.The difference of their photophysical properties was investigated by the aid of ultraviolet-visible absorption and fluorescence spectrophotometers.Furthermore,the stacking patterns of 7 and its contrastπ-conjugated macrocycle trimer(2)were compared via the analysis of X-ray single crystal,in which the electron-deficient dibenzo[a,c]phenazine unit provides extra interaction sites,resulting in orderly arrangement of 7 in the solid state.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(2021QZKK0100)the National Key Research and Development Plans(2021YFC0863400)+2 种基金the National Key Research and Development Plans(2021YFC2300904)the National Natural Science Foundation of China General Program(42171144)the National Natural Science Foundation of China for Excellent Young Scientists Fund Program(42222105)。
基金The work was supported by grants from the National Key Research and Development Program of China(No.2019YFA0308500)the National Natural Science Foundation of China(No.61888102)+5 种基金the Chinese Academy of Sciences(Nos.XDB30000000 and YSBR-003)the EU Graphene Flagship(Graphene Core 3,No.881603)the H2020-MSCA-ITN(ULTIMATE,No.813036)the Center for Advancing Electronics Dresden(CfAED)the H2020-EU.1.2.2.-FET Proactive Grant(LIGHT-CAP,No.101017821)the DFG-SNSF Joint Switzerland-German Research Project(EnhanTopo,No.429265950).
文摘Zigzag graphene nanoribbons(ZGNRs)with spin-polarized edge states have potential applications in carbon-based spintronics.The electronic structure of ZGNRs can be effectively tuned by different widths or dopants,which requires delicately designed monomers.Here,we report the successful synthesis of ZGNR with a width of eight carbon zigzag lines and nitrogen-boronnitrogen(NBN)motifs decorated along the zigzag edges(NBN-8-ZGNR)on Au(111)surface,which starts from a specially designed U-shaped monomer with preinstalled NBN units at the zigzag edge.Chemical-bond-resolved non-contact atomic force microscopy(nc-AFM)imaging confirms the zigzag-terminated edges and the existence of NBN dopants.The electronic states distributed along the zigzag edges have been revealed after a silicon-layer intercalation at the interface of NBN-8-ZGNR and Au(111).Our work enriches the ZGNR family with a new dopant and larger width,which provides more candidates for future carbonbased nanoelectronic and spintronic applications.
