On-surface Ullmann-type reaction,or the dehalogenated coupling,is arguably the most pivotal reaction in on-surface synthesis for the fabrications of carbon nanostructures.Hitherto,the vast majority of works rely on ac...On-surface Ullmann-type reaction,or the dehalogenated coupling,is arguably the most pivotal reaction in on-surface synthesis for the fabrications of carbon nanostructures.Hitherto,the vast majority of works rely on activating the C-Br bond of aryl bromide which has a moderate bond dissociation energy.The C-Cl bond of aryl chloride has a higher dissociation energy and requires much higher thermal energy to break the bond.In this study,we have explored the on-surface photo-induced dechlorination and achieved the activation of three distinct aryl chlorines on the Au(111)surface with mild temperatures.This work enriches our understanding of on-surface photo-induced reactions and highlights the potential of photochemistry in realizing unconventional reactions.展开更多
On-surface synthesis of semiconducting graphdiyne nanowires usually suffer severe side reactions owing to the high reactivity of the butadiynylene units at noble metal surfaces,limiting the production of isolated nano...On-surface synthesis of semiconducting graphdiyne nanowires usually suffer severe side reactions owing to the high reactivity of the butadiynylene units at noble metal surfaces,limiting the production of isolated nanowires. In this work, we report the high-yield synthesis of branchless graphdiyne nanowires [-C≡C-Ph2-C≡C-]nvia on-surface Ullmann coupling of 1,4-bis（4-bromophenyl）-1,3-butadiyne molecules with chemical vapor deposition method.Non-contact atomic force microscopy with single-bond resolution reveals that single gold adatoms act as effective protecting groups for butadiynylene units by forming Au-π ligand bonds, preventing unwanted branched coupling reactions and enabling the synthesis of ultralong isolated graphdiyne nanowires. This study will stimulate further investigation on the role of various surface adatoms in protecting on-surface reactions.展开更多
Carbyne is an infinite one-dimensional carbon chain comprising of sp-hybridized carbons.Due to its high chemical reactivity and extreme instability,the synthesis and structural diversity of carbyne have been much less...Carbyne is an infinite one-dimensional carbon chain comprising of sp-hybridized carbons.Due to its high chemical reactivity and extreme instability,the synthesis and structural diversity of carbyne have been much less investigated in the past decades compared to carbon allotropes built with sp^(2)hybridized carbons,such as fullerenes,carbon nanotubes,and graphene.The emerging on-surface synthesis strategy provides an extremely promising approach for the fabrication of novel carbyne-like nanostructures with atomic precision.Herein,we summarize recent exciting progress in the synthesis of carbyne-like nanostructures with one-dimensional sp-carbon on surfaces,including polyynes,cumulenes,and organometallic polyynes.We also point out the scientific challenges and prospects,encouraging scientists to explore the fabrication and characterization of single strands of carbyne in this young and promising research field.展开更多
Bottom-up approach to constructing low-dimensional nanostructures on surfaces with terminal alkynes has drawn great interest because of its potential applications in fabricating advanced functional nanomaterials. The ...Bottom-up approach to constructing low-dimensional nanostructures on surfaces with terminal alkynes has drawn great interest because of its potential applications in fabricating advanced functional nanomaterials. The diversity of the achieved products manifests rich chemistry of terminal alkynes and hence careful linking strategies and proper controlling methodologies are required for selective preparations of high-quality target nanoarchitectures. This review summarizes various on-surface linking strategies for terminal alkynes, including non-bonding interactions as well as organometallic and covalent bonds, and presents examples to show effective control of surface assemblies and reactions of terminal alkynes by variations of the precursor structures, substrates and activation modes. Systematic studies of the on-surface linkage of terminal alkynes may help efficient and predictable preparations of surface nanomaterials and further understanding of surface chemistry.展开更多
Large language models(LLMs)excel at extracting information from literatures.However,deploying LLMs necessitates substantial computational resources,and security concerns with online LLMs pose a challenge to their wide...Large language models(LLMs)excel at extracting information from literatures.However,deploying LLMs necessitates substantial computational resources,and security concerns with online LLMs pose a challenge to their wider applications.Herein,we introduce a method for extracting scientific data from unstructured texts using a local LLM,exemplifying its applications to scientific literatures on the topic of on-surface reactions.By combining prompt engineering and multi-step text preprocessing,we show that the local LLM can effectively extract scientific information,achieving a recall rate of 91%and a precision rate of 70%.Moreover,despite significant differences in model parameter size,the performance of the local LLM is comparable to that of GPT-3.5 turbo(81%recall,84%precision)and GPT-4o(85%recall,87%precision).The simplicity,versatility,reduced computational requirements,and enhanced privacy of the local LLM makes it highly promising for data mining,with the potential to accelerate the application and development of LLMs across variousfields.展开更多
Precise construction of quantum spin chains is essential for studying their complex physical properties and for their potential applications in quantum devices.Polymers provide an excellent foundation for building spi...Precise construction of quantum spin chains is essential for studying their complex physical properties and for their potential applications in quantum devices.Polymers provide an excellent foundation for building spin chain systems due to their stability and flexibility,while a strategy is required for the creation and protection of spins on the chains.Here we report the fabrication and characterization of spin 1/2 polyfluorene-based chains through on-surface synthetic approach.Dehydroxylation is used to create spins on polyfluorene-based chains,and side groups(phenyl rings)are used to protect the spins from further reactions.The coupling strength between spins is identified in transport measurements with chains suspended between the tip and the sample of a scanning tunneling microscope.Furthermore,collective spin excitations emerge in the decoupled chains.Mean-field Hubbard simulations confirm the antiferromagnetic ground states,and Heisenberg spin model calculations capture the complex spin excitation behaviors.Our results demonstrate the use of polymers to construct spin chain systems,paving a way for study and manipulation of quantum properties in polymers chains.展开更多
On-surface synthesis has emerged as a powerful strategy to fabricate unprecedented forms of atomically precise graphene nanoribbons(GNRs).However,the on-surface synthesis of zigzag GNRs(ZGNR)has met with only limited ...On-surface synthesis has emerged as a powerful strategy to fabricate unprecedented forms of atomically precise graphene nanoribbons(GNRs).However,the on-surface synthesis of zigzag GNRs(ZGNR)has met with only limited success.Herein,we report the synthesis and on-surface reactions of 2,7-dibromo-9,9′-bianthryl as the precursor towardπ-extended ZGNRs.Characterization by scanning tunneling microscopy and high-resolution noncontact atomic force microscopy clearly demonstrated the formation of anthracene-fused ZGNRs.Unique skeletal rearrangements were also observed,which could be explained by intramolecular Diels-Alder cycloaddition.Theoretical calculations of the electronic properties of the anthracene-fused ZGNRs revealed spin-polarized edge-states and a narrow bandgap of 0.20 eV.展开更多
Imide-based conjugated molecules have emerged as a highly promising class of building blocks for constructing n-type semiconducting materials with lowlying lowest unoccupied molecular orbitals and exceptional stabilit...Imide-based conjugated molecules have emerged as a highly promising class of building blocks for constructing n-type semiconducting materials with lowlying lowest unoccupied molecular orbitals and exceptional stability.Although imides,such as naphthalene diimides,perylene diimides and their lateral fused analogs,have been synthesized extensively,the design and synthesis of largerπ-extended molecules incorporating more than two imide groups are desirable but still very challenging.Herein,we report the synthesis of an unprecedented electron-deficient bisanthene tetraimide(ATI)containing a bisantheneconjugated core and four five-membered imide groups,which was successfully achieved via a combined approach of solution and on-surface synthesis.The chemical structures,electronic states,formation mechanism and aromaticity of ATI were systematically investigated by scanning tunneling microscopy,noncontact atomic force microscopy,scanning tunneling spectroscopy,and density functional theory calculations.展开更多
Carbohelicenes have garnered considerable attention for their inherent chirality and structural flexibility.Increasing multi-helicity and incorporating non-six-membered rings to substitute benzenoid rings within helic...Carbohelicenes have garnered considerable attention for their inherent chirality and structural flexibility.Increasing multi-helicity and incorporating non-six-membered rings to substitute benzenoid rings within helicenes are effective strategies for introducing unique photoelectric properties.Despite the disclosure of numerous helicenes,the inaccessible precursors and the lack of synthetic routes pose a challenge in achieving desired helicene structures fused with non-benzenoid rings.Herein,we report the synthesis of multiple non-benzenoid carbohelicenes fused with fluorene unit(s)through intramolecular cyclodehydrogenation of 9,10-di(naphthalen-1-yl)anthracene on Au(111)surface.Two potential cyclodehydrogenation manners between naphthyl and anthracene lead to the formation of fluorene-fused[5]helicene and[4]helicene moiety.Consequently,a total of four stable products were observed.The atomic topographies of products are characterized by bond-resolving scanning tunneling microscopy.The chiral helicity of targeted products can be switched by tip manipulation.Density-functional-theory calculations unveils the reaction pathway of four products.The comparative analysis of their respective energy barriers exhibits a correlation with the experimentally determined yields.Furthermore,we synthesize the polymer chains incorporating non-benzenoid carbohelicenes via the Ullmann reaction of 2,6-dibromo-9,10-di(1-naphthyl)anthracene precursors.Our work proposes a synthetic methodology for several novel helicene-like structures fused with fluorene units and the polymer bearing helicene subunits,thus highlighting the immense potential of these compounds in the application fields of luminescent electronic devices.展开更多
Graphyne,a remarkable two-dimensional carbon allotrope,has attracted significant attention in the field of materials science due to its unique properties and potential applications.Because of the special arrangement o...Graphyne,a remarkable two-dimensional carbon allotrope,has attracted significant attention in the field of materials science due to its unique properties and potential applications.Because of the special arrangement of their sp-and sp^(2)-hybridized carbon atoms,these structures display a wide range of geometrical and electronic characteristics as well as homogeneous pores of varying sizes,making them suitable for a variety of practical applications.In recent years,the synthesis of the thin film products of graphyne and its derivatives has typically been documented.To date,however,it remains challenging to synthesize atomically precise single-layered graphyne and its derivatives.Herein,we report a facile strategy to synthesize single-layered hydrogen-substituted γ-graphdiyne on the Au(111)surface through dehalogenation and intermolecular coupling polymerization.Its geometric atomic structure was investigated by scanning probe microscopy.Combined with theoretical results,we reveal its semiconducting property.展开更多
Graphene nanoribbons (GNRs) have potential for applications in electronic devices. A key issue, thereby, is the fine-tuning of their electronic characteristics, which can be achieved through subtle structural modifica...Graphene nanoribbons (GNRs) have potential for applications in electronic devices. A key issue, thereby, is the fine-tuning of their electronic characteristics, which can be achieved through subtle structural modifications. These are not limited to the conventional armchair, zigzag, and cove edges, but also possible through incorporation of non-hexagonal rings. On-surface synthesis enables the fabrication and visualization of GNRs with atomically precise chemical structures, but strategies for the incorporation of non-hexagonal rings have been underexplored. Herein, we describe the on-surface synthesis of armchair-edged GNRs with incorporated five-membered rings through the C-H activation and cyclization of benzylic methyl groups. Ortho-Tolyl-substituted dibromobianthryl was employed as the precursor monomer, and visualization of the resulting structures after annealing at 300 °C on a gold surface by high-resolution noncontact atomic force microscopy clearly revealed the formation of methylene-bridged pentagons at the GNR edges. These persisted after annealing at 340 °C, along with a few fully conjugated pentagons having singly-hydrogenated apexes. The benzylic methyl groups could also migrate or cleave-off, resulting in defects lacking the five-membered rings. Moreover, unexpected and unique structural rearrangements, including the formation of embedded heptagons, were observed. Despite the coexistence of different reaction pathways that hamper selective synthesis of a uniform structure, our results provide novel insights into on-surface reactions en route to functional, non-benzenoid carbon nanomaterials.展开更多
Chemistry on solid surfaces is central to many research areas of practical interest,such as synthesis,catalysis,electrochemistry,photochemistry,and materials science.A comprehensive understanding of the nanoscale on-s...Chemistry on solid surfaces is central to many research areas of practical interest,such as synthesis,catalysis,electrochemistry,photochemistry,and materials science.A comprehensive understanding of the nanoscale on-surface chemistry involved in these areas is important for establishing composition-structure-performance relationships.With the rapid development of tip-enhanced Raman spectroscopy(TERS),it has become possible to investigate physical and chemical processes on suitable surfaces at the nanoscale level and in real space.In this review,after a brief introduction of the background of onsurface chemistry and TERS,we systematically discuss the progress in the application of TERS in this field.Our focus is the applications of TERS to nanoscale coordination processes,decomposition reactions,polymerization processes,electrochemical reactions,catalytic chemistry,and functionalization chemistry on solid surfaces.We conclude by discussing the future challenges and development of TERS techniques and related applications in on-surface chemistry.展开更多
On-surface synthesis under ultrahigh vacuum provides a promising strategy to control matter at the atomic level, with important implications for the design of new two-dimensional materials having remarkable electronic...On-surface synthesis under ultrahigh vacuum provides a promising strategy to control matter at the atomic level, with important implications for the design of new two-dimensional materials having remarkable electronic, magnetic, or catalytic properties. This strategy must address the problem of limited extension of the domains due to the irreversible nature of covalent bonds, which prevents the ripening of defects. We show here that extended materials can be produced by a controlled co-deposition process. In particular, co-deposition of quinoid zwitterion molecules with iron atoms on a Ag（111） surface held at 570 K allows the formation of micrometer-sized domains based on covalent coordination bonds. This work opens up the construction of micrometer-scale single-layer covalent coordination materials under vacuum conditions.展开更多
On-surface synthesis never fails to fascinate chemists by producing new functional polymers which can hardly been prepared via traditional solution chemistry.Among those newly prepared polymers,graphene nanoribbons(GN...On-surface synthesis never fails to fascinate chemists by producing new functional polymers which can hardly been prepared via traditional solution chemistry.Among those newly prepared polymers,graphene nanoribbons(GNRs),featured with tunable band gap,have attracted substantial attention because they are considered as promising candidates for next generation carbon-based semiconductors.Here,we summarize the recent advances of GNRs prepared on single crystal surfaces with emphasis on the structural tuning and electronic properties of GNRs.Moreover,critical developments toward the application of GNRs have also been reviewed including the mass fabrication and the performance of GNRs as field effect transistors.展开更多
Metallo-porphyrins with different metal centers display unique properties and are essential in various biological and chemical processes.Enormous efforts have been devoted to enriching the family of metallo-porphyrins...Metallo-porphyrins with different metal centers display unique properties and are essential in various biological and chemical processes.Enormous efforts have been devoted to enriching the family of metallo-porphyrins on surfaces mainly through metalation processes within porphyrins and exogenous pure metals or intrinsic surface adatoms,which have focused on transition elements.However,less attention has been paid to the synthesis of alkali-metal-based porphyrins on a surface.Herein,by a combination of scanning tunneling microscopy(STM)imaging/manipulations and density functional theory(DFT)calculations,we report the fabrication of Na-porphyrins on Au(111)by introducing NaCl,i.e.,two double-layered Na-centered porphyrins.Moreover,the interconversion between them was realized by precise STM manipulations.Our results demonstrate the feasibility of metalation by applying inorganic salt,which would serve as a promising strategy to embed intramolecular metal components into porphyrins for further functionalization and modification.展开更多
On-surface synthesis is a rapidly developing field involving chemical reactions on well-defined solid surfaces toaccess synthesis of low-dimensional organic nanostructures which cannot be achieved via traditional solu...On-surface synthesis is a rapidly developing field involving chemical reactions on well-defined solid surfaces toaccess synthesis of low-dimensional organic nanostructures which cannot be achieved via traditional solutionchemistry. On-surface reactions critically depend on a high degree of chemoselectivity in order to achieve anoptimum balance between target structure and possible side products. Here, we demonstrate synthesis of graphenenanoribbons with a large unit cell based on steric hindrance-induced complete chemoselectivity as revealed byscanning probe microscopy measurements and density functional theory calculations. Our results disclose thatcombined molecule-substrate van der Waals interactions and intermolecular steric hindrance promote a selectivearyl-aryl coupling, giving rise to high-quality uniform graphene nanostructures. The established coupling strategyhas been used to synthesize two types of graphene nanoribbons with different edge topologies inducing apronounced variation of the electronic energy gaps. The demonstrated chemoselectivity is representative forn-anthryl precursor molecules and may be further exploited to synthesize graphene nanoribbons with novelelectronic, topological and magnetic properties with implications for electronic and spintronic applications.展开更多
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
The linkage structures between monomers make great influence on the properties of polymers.The synthesis of some special linkage structures can be challenging,which is often overcome by employing special reaction cond...The linkage structures between monomers make great influence on the properties of polymers.The synthesis of some special linkage structures can be challenging,which is often overcome by employing special reaction conditions.Here,we build dihydropentalene linkage in poly-naphthalocyanine on Ag(110)surface.Scanning tunneling microscopy(STM)and non-contact atomic force microscopy(nc-AFM)measurements confirm the dihydropentalene linkage structure and a possible formation path with reconstruction steps is proposed.The controlled experiment on Ag(100)surface shows no dihydropentalene structures formed,which indicates the grooved substrate is necessary for the reconstruction.This work provides insights into the surface restricted reactions that can yield special structures in organic polymers.展开更多
The Kagome-honeycomb lattice has attracted significant interest as a platform for realizing exotic quantum states,owing to its unique electronic and magnetic properties.In this study,we report the synthesis of a two-d...The Kagome-honeycomb lattice has attracted significant interest as a platform for realizing exotic quantum states,owing to its unique electronic and magnetic properties.In this study,we report the synthesis of a two-dimensional Kagome-honeycomb lattice composed of nitrogen-doped macrocyclic aromatic hydrocarbons.By leveraging the synergistic influence of thermodynamically driven macrocyclization,the efficient organometallic template,and the steric hindrance induced by close-packed assemblies,submicron-scale Kagome-honeycomb crystalline films were obtained.With the combination of scanning tunneling microscopy(STM),high-resolution synchrotron radiation photoemission spectroscopy(SRPES),and density functional theory(DFT)calculations,the underlying reaction mechanisms were systematically revealed by investigating the reaction intermediates and products during the formation of the Kagome-honeycomb lattice.This work provides a promising pathway for the synthesis of Kagome-honeycomb lattices and offers a platform for exploring their novel physical properties.展开更多
基金supported by National Natural Science Foundation of China(Nos.22072086,22302120)。
文摘On-surface Ullmann-type reaction,or the dehalogenated coupling,is arguably the most pivotal reaction in on-surface synthesis for the fabrications of carbon nanostructures.Hitherto,the vast majority of works rely on activating the C-Br bond of aryl bromide which has a moderate bond dissociation energy.The C-Cl bond of aryl chloride has a higher dissociation energy and requires much higher thermal energy to break the bond.In this study,we have explored the on-surface photo-induced dechlorination and achieved the activation of three distinct aryl chlorines on the Au(111)surface with mild temperatures.This work enriches our understanding of on-surface photo-induced reactions and highlights the potential of photochemistry in realizing unconventional reactions.
基金the National Key R&D Program of China(No.2016YFA0200603 No.2017YFA0205004)the Anhui Initiative in Quantum Information Technologies(AHY090300)+2 种基金the National Natural Science Foundation of China(No.21473174)the Fundamental Research Funds for the Central Universities(No.WK2060190084 and No.WK2340000082)Ai-di Zhao acknowledges a fellow-ship from the Youth Innovation Promotion Association of Chinese Academy of Science(2011322).
文摘On-surface synthesis of semiconducting graphdiyne nanowires usually suffer severe side reactions owing to the high reactivity of the butadiynylene units at noble metal surfaces,limiting the production of isolated nanowires. In this work, we report the high-yield synthesis of branchless graphdiyne nanowires [-C≡C-Ph2-C≡C-]nvia on-surface Ullmann coupling of 1,4-bis（4-bromophenyl）-1,3-butadiyne molecules with chemical vapor deposition method.Non-contact atomic force microscopy with single-bond resolution reveals that single gold adatoms act as effective protecting groups for butadiynylene units by forming Au-π ligand bonds, preventing unwanted branched coupling reactions and enabling the synthesis of ultralong isolated graphdiyne nanowires. This study will stimulate further investigation on the role of various surface adatoms in protecting on-surface reactions.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.22125203 and 21790351)
文摘Carbyne is an infinite one-dimensional carbon chain comprising of sp-hybridized carbons.Due to its high chemical reactivity and extreme instability,the synthesis and structural diversity of carbyne have been much less investigated in the past decades compared to carbon allotropes built with sp^(2)hybridized carbons,such as fullerenes,carbon nanotubes,and graphene.The emerging on-surface synthesis strategy provides an extremely promising approach for the fabrication of novel carbyne-like nanostructures with atomic precision.Herein,we summarize recent exciting progress in the synthesis of carbyne-like nanostructures with one-dimensional sp-carbon on surfaces,including polyynes,cumulenes,and organometallic polyynes.We also point out the scientific challenges and prospects,encouraging scientists to explore the fabrication and characterization of single strands of carbyne in this young and promising research field.
基金jointly supported by National Natural Science Foundation of China (NSFC) (Nos. 91527303, 21333001)
文摘Bottom-up approach to constructing low-dimensional nanostructures on surfaces with terminal alkynes has drawn great interest because of its potential applications in fabricating advanced functional nanomaterials. The diversity of the achieved products manifests rich chemistry of terminal alkynes and hence careful linking strategies and proper controlling methodologies are required for selective preparations of high-quality target nanoarchitectures. This review summarizes various on-surface linking strategies for terminal alkynes, including non-bonding interactions as well as organometallic and covalent bonds, and presents examples to show effective control of surface assemblies and reactions of terminal alkynes by variations of the precursor structures, substrates and activation modes. Systematic studies of the on-surface linkage of terminal alkynes may help efficient and predictable preparations of surface nanomaterials and further understanding of surface chemistry.
基金supported by the National Natural Science Foundation of China(Grant Nos.22072086,22302120).
文摘Large language models(LLMs)excel at extracting information from literatures.However,deploying LLMs necessitates substantial computational resources,and security concerns with online LLMs pose a challenge to their wider applications.Herein,we introduce a method for extracting scientific data from unstructured texts using a local LLM,exemplifying its applications to scientific literatures on the topic of on-surface reactions.By combining prompt engineering and multi-step text preprocessing,we show that the local LLM can effectively extract scientific information,achieving a recall rate of 91%and a precision rate of 70%.Moreover,despite significant differences in model parameter size,the performance of the local LLM is comparable to that of GPT-3.5 turbo(81%recall,84%precision)and GPT-4o(85%recall,87%precision).The simplicity,versatility,reduced computational requirements,and enhanced privacy of the local LLM makes it highly promising for data mining,with the potential to accelerate the application and development of LLMs across variousfields.
基金the support by National Natural Science Foundation of China(No.12474181)Guangdong Basic and Applied Basic Research Foundation(Nos.2021B0301030002 and 2024A1515010656)Guangdong Science and Technology Project(No.2021QN02X859).
文摘Precise construction of quantum spin chains is essential for studying their complex physical properties and for their potential applications in quantum devices.Polymers provide an excellent foundation for building spin chain systems due to their stability and flexibility,while a strategy is required for the creation and protection of spins on the chains.Here we report the fabrication and characterization of spin 1/2 polyfluorene-based chains through on-surface synthetic approach.Dehydroxylation is used to create spins on polyfluorene-based chains,and side groups(phenyl rings)are used to protect the spins from further reactions.The coupling strength between spins is identified in transport measurements with chains suspended between the tip and the sample of a scanning tunneling microscope.Furthermore,collective spin excitations emerge in the decoupled chains.Mean-field Hubbard simulations confirm the antiferromagnetic ground states,and Heisenberg spin model calculations capture the complex spin excitation behaviors.Our results demonstrate the use of polymers to construct spin chain systems,paving a way for study and manipulation of quantum properties in polymers chains.
基金This work was supported by the Swiss National Science Foundation(Grant No.200020_212875)the NCCR MAR-VEL funded by the Swiss National Science Foundation(Grant No.205602)the Werner Siemens Foundation,the Max Planck Society,and the Okinawa Institute of Science and Technology Graduate University.K.M.acknowledges a fellowship from Gutenberg Research College,Johannes Gutenberg University Mainz.Computational support from the Swiss Supercomputing Center(CSCS)under project ID s1141 is gratefully acknowl-edged.We acknowledge PRACE for awarding access to the Fenix Infrastructure resources at CSCS,which are partially funded by the European Union’s Horizon 2020 research and innovation program through the ICEI project under grant agreement No.800858.Technical support from Lukas Rotach is gratefully acknowledged.
文摘On-surface synthesis has emerged as a powerful strategy to fabricate unprecedented forms of atomically precise graphene nanoribbons(GNRs).However,the on-surface synthesis of zigzag GNRs(ZGNR)has met with only limited success.Herein,we report the synthesis and on-surface reactions of 2,7-dibromo-9,9′-bianthryl as the precursor towardπ-extended ZGNRs.Characterization by scanning tunneling microscopy and high-resolution noncontact atomic force microscopy clearly demonstrated the formation of anthracene-fused ZGNRs.Unique skeletal rearrangements were also observed,which could be explained by intramolecular Diels-Alder cycloaddition.Theoretical calculations of the electronic properties of the anthracene-fused ZGNRs revealed spin-polarized edge-states and a narrow bandgap of 0.20 eV.
基金support from the National Natural Science Foundation of China(grant nos.22161132026,21790053,51821002,and 21602225)the Suzhou Key Laboratory of Surface and Interface Intelligent Matter(grant no.SZS2022011)+2 种基金the Collaborative Innovation Center of Suzhou Nano Science and Technologythe Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)the 111 project.
文摘Imide-based conjugated molecules have emerged as a highly promising class of building blocks for constructing n-type semiconducting materials with lowlying lowest unoccupied molecular orbitals and exceptional stability.Although imides,such as naphthalene diimides,perylene diimides and their lateral fused analogs,have been synthesized extensively,the design and synthesis of largerπ-extended molecules incorporating more than two imide groups are desirable but still very challenging.Herein,we report the synthesis of an unprecedented electron-deficient bisanthene tetraimide(ATI)containing a bisantheneconjugated core and four five-membered imide groups,which was successfully achieved via a combined approach of solution and on-surface synthesis.The chemical structures,electronic states,formation mechanism and aromaticity of ATI were systematically investigated by scanning tunneling microscopy,noncontact atomic force microscopy,scanning tunneling spectroscopy,and density functional theory calculations.
基金supported by the National Natural Science Foundation of China(Nos.62271238,22372074,62301240)Yunnan Fundamental Research Projects(Nos.202201AT070078,202201BE070001-009 and 202301AW070017)+3 种基金the Major Basic Research Project of Science and Technology of Yunnan(202302AG050007)Yunnan Innovation Team of Graphene Mechanism Research and Application Industrialization(202305AS350017)Graphene Application and Engineering Research Centre of Education Department of Yunnan Providence(KKPP202351001)the Analysis and Testing Foundation of KUST(2021T20170056).
文摘Carbohelicenes have garnered considerable attention for their inherent chirality and structural flexibility.Increasing multi-helicity and incorporating non-six-membered rings to substitute benzenoid rings within helicenes are effective strategies for introducing unique photoelectric properties.Despite the disclosure of numerous helicenes,the inaccessible precursors and the lack of synthetic routes pose a challenge in achieving desired helicene structures fused with non-benzenoid rings.Herein,we report the synthesis of multiple non-benzenoid carbohelicenes fused with fluorene unit(s)through intramolecular cyclodehydrogenation of 9,10-di(naphthalen-1-yl)anthracene on Au(111)surface.Two potential cyclodehydrogenation manners between naphthyl and anthracene lead to the formation of fluorene-fused[5]helicene and[4]helicene moiety.Consequently,a total of four stable products were observed.The atomic topographies of products are characterized by bond-resolving scanning tunneling microscopy.The chiral helicity of targeted products can be switched by tip manipulation.Density-functional-theory calculations unveils the reaction pathway of four products.The comparative analysis of their respective energy barriers exhibits a correlation with the experimentally determined yields.Furthermore,we synthesize the polymer chains incorporating non-benzenoid carbohelicenes via the Ullmann reaction of 2,6-dibromo-9,10-di(1-naphthyl)anthracene precursors.Our work proposes a synthetic methodology for several novel helicene-like structures fused with fluorene units and the polymer bearing helicene subunits,thus highlighting the immense potential of these compounds in the application fields of luminescent electronic devices.
基金the financial support of this work from the National Key R&D Program of China(2023YFE0101900,from the Ministry of Science and Technology of the People’s Republic of China)the National Natural Science Foundation of China(grant nos.22125203 and 21790351)。
文摘Graphyne,a remarkable two-dimensional carbon allotrope,has attracted significant attention in the field of materials science due to its unique properties and potential applications.Because of the special arrangement of their sp-and sp^(2)-hybridized carbon atoms,these structures display a wide range of geometrical and electronic characteristics as well as homogeneous pores of varying sizes,making them suitable for a variety of practical applications.In recent years,the synthesis of the thin film products of graphyne and its derivatives has typically been documented.To date,however,it remains challenging to synthesize atomically precise single-layered graphyne and its derivatives.Herein,we report a facile strategy to synthesize single-layered hydrogen-substituted γ-graphdiyne on the Au(111)surface through dehalogenation and intermolecular coupling polymerization.Its geometric atomic structure was investigated by scanning probe microscopy.Combined with theoretical results,we reveal its semiconducting property.
基金We are grateful for the financial support by the Max Planck Society,the Swiss National Science Foundation under Grant No.200020_182015the NCCR MARVEL funded by the Swiss National Science Foundation(No.51NF40-182892)+3 种基金the European Union’s Horizon 2020 research and innovation programme under grant agreement number 785219(Graphene Flagship Core 2)the Office of Naval Research(No.N00014-18-1-2708)the Okinawa Institute of Science and Technology Graduate University(OIST)The Swiss National Supercomputing Centre(CSCS)under project ID s904 is acknowledged for computational resources.
文摘Graphene nanoribbons (GNRs) have potential for applications in electronic devices. A key issue, thereby, is the fine-tuning of their electronic characteristics, which can be achieved through subtle structural modifications. These are not limited to the conventional armchair, zigzag, and cove edges, but also possible through incorporation of non-hexagonal rings. On-surface synthesis enables the fabrication and visualization of GNRs with atomically precise chemical structures, but strategies for the incorporation of non-hexagonal rings have been underexplored. Herein, we describe the on-surface synthesis of armchair-edged GNRs with incorporated five-membered rings through the C-H activation and cyclization of benzylic methyl groups. Ortho-Tolyl-substituted dibromobianthryl was employed as the precursor monomer, and visualization of the resulting structures after annealing at 300 °C on a gold surface by high-resolution noncontact atomic force microscopy clearly revealed the formation of methylene-bridged pentagons at the GNR edges. These persisted after annealing at 340 °C, along with a few fully conjugated pentagons having singly-hydrogenated apexes. The benzylic methyl groups could also migrate or cleave-off, resulting in defects lacking the five-membered rings. Moreover, unexpected and unique structural rearrangements, including the formation of embedded heptagons, were observed. Despite the coexistence of different reaction pathways that hamper selective synthesis of a uniform structure, our results provide novel insights into on-surface reactions en route to functional, non-benzenoid carbon nanomaterials.
基金We acknowledge financial support from the ERC program(Grant No.741431-2DNanoSpec).
文摘Chemistry on solid surfaces is central to many research areas of practical interest,such as synthesis,catalysis,electrochemistry,photochemistry,and materials science.A comprehensive understanding of the nanoscale on-surface chemistry involved in these areas is important for establishing composition-structure-performance relationships.With the rapid development of tip-enhanced Raman spectroscopy(TERS),it has become possible to investigate physical and chemical processes on suitable surfaces at the nanoscale level and in real space.In this review,after a brief introduction of the background of onsurface chemistry and TERS,we systematically discuss the progress in the application of TERS in this field.Our focus is the applications of TERS to nanoscale coordination processes,decomposition reactions,polymerization processes,electrochemical reactions,catalytic chemistry,and functionalization chemistry on solid surfaces.We conclude by discussing the future challenges and development of TERS techniques and related applications in on-surface chemistry.
文摘On-surface synthesis under ultrahigh vacuum provides a promising strategy to control matter at the atomic level, with important implications for the design of new two-dimensional materials having remarkable electronic, magnetic, or catalytic properties. This strategy must address the problem of limited extension of the domains due to the irreversible nature of covalent bonds, which prevents the ripening of defects. We show here that extended materials can be produced by a controlled co-deposition process. In particular, co-deposition of quinoid zwitterion molecules with iron atoms on a Ag（111） surface held at 570 K allows the formation of micrometer-sized domains based on covalent coordination bonds. This work opens up the construction of micrometer-scale single-layer covalent coordination materials under vacuum conditions.
文摘On-surface synthesis never fails to fascinate chemists by producing new functional polymers which can hardly been prepared via traditional solution chemistry.Among those newly prepared polymers,graphene nanoribbons(GNRs),featured with tunable band gap,have attracted substantial attention because they are considered as promising candidates for next generation carbon-based semiconductors.Here,we summarize the recent advances of GNRs prepared on single crystal surfaces with emphasis on the structural tuning and electronic properties of GNRs.Moreover,critical developments toward the application of GNRs have also been reviewed including the mass fabrication and the performance of GNRs as field effect transistors.
基金the National Natural Science Foundation of China(Grants Nos.22125203,21790351,and 22202153)the Fundamental Research Funds for the Central Universities,and Covestro.
文摘Metallo-porphyrins with different metal centers display unique properties and are essential in various biological and chemical processes.Enormous efforts have been devoted to enriching the family of metallo-porphyrins on surfaces mainly through metalation processes within porphyrins and exogenous pure metals or intrinsic surface adatoms,which have focused on transition elements.However,less attention has been paid to the synthesis of alkali-metal-based porphyrins on a surface.Herein,by a combination of scanning tunneling microscopy(STM)imaging/manipulations and density functional theory(DFT)calculations,we report the fabrication of Na-porphyrins on Au(111)by introducing NaCl,i.e.,two double-layered Na-centered porphyrins.Moreover,the interconversion between them was realized by precise STM manipulations.Our results demonstrate the feasibility of metalation by applying inorganic salt,which would serve as a promising strategy to embed intramolecular metal components into porphyrins for further functionalization and modification.
基金support from the Swiss National Science Foundation under Grant No.200020_182015support by the Max Planck Society.CAP acknowledges the NCCR MARVEL funded by the Swiss National Science Foundation(grant no.51NF40-205602)The Swiss Supercomputing Center(CSCS)is acknowledged for computational resources(project ID s1141).
文摘On-surface synthesis is a rapidly developing field involving chemical reactions on well-defined solid surfaces toaccess synthesis of low-dimensional organic nanostructures which cannot be achieved via traditional solutionchemistry. On-surface reactions critically depend on a high degree of chemoselectivity in order to achieve anoptimum balance between target structure and possible side products. Here, we demonstrate synthesis of graphenenanoribbons with a large unit cell based on steric hindrance-induced complete chemoselectivity as revealed byscanning probe microscopy measurements and density functional theory calculations. Our results disclose thatcombined molecule-substrate van der Waals interactions and intermolecular steric hindrance promote a selectivearyl-aryl coupling, giving rise to high-quality uniform graphene nanostructures. The established coupling strategyhas been used to synthesize two types of graphene nanoribbons with different edge topologies inducing apronounced variation of the electronic energy gaps. The demonstrated chemoselectivity is representative forn-anthryl precursor molecules and may be further exploited to synthesize graphene nanoribbons with novelelectronic, topological and magnetic properties with implications for electronic and spintronic applications.
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the National Natural Science Foundation of China(Grant No.61888102)the National Key Research and Development Program of China(Grant Nos.2018YFA0305800 and 2019YFA0308500)+1 种基金Chinese Academy of Sciences(Grant Nos.XDB30000000,YSBR003,and 112111KYSB20160061)the Fundamental Research Funds for the Central Universities,China.
文摘The linkage structures between monomers make great influence on the properties of polymers.The synthesis of some special linkage structures can be challenging,which is often overcome by employing special reaction conditions.Here,we build dihydropentalene linkage in poly-naphthalocyanine on Ag(110)surface.Scanning tunneling microscopy(STM)and non-contact atomic force microscopy(nc-AFM)measurements confirm the dihydropentalene linkage structure and a possible formation path with reconstruction steps is proposed.The controlled experiment on Ag(100)surface shows no dihydropentalene structures formed,which indicates the grooved substrate is necessary for the reconstruction.This work provides insights into the surface restricted reactions that can yield special structures in organic polymers.
基金financially supported by the National Key R&D Program of China(No.2024YFA1208102)the National Natural Science Foundation of China(Nos.22272157,21872131,and U2430203)+1 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB1180000)State Key Laboratory of Explosion Science and Safety Protection(No.QKKT25-01).
文摘The Kagome-honeycomb lattice has attracted significant interest as a platform for realizing exotic quantum states,owing to its unique electronic and magnetic properties.In this study,we report the synthesis of a two-dimensional Kagome-honeycomb lattice composed of nitrogen-doped macrocyclic aromatic hydrocarbons.By leveraging the synergistic influence of thermodynamically driven macrocyclization,the efficient organometallic template,and the steric hindrance induced by close-packed assemblies,submicron-scale Kagome-honeycomb crystalline films were obtained.With the combination of scanning tunneling microscopy(STM),high-resolution synchrotron radiation photoemission spectroscopy(SRPES),and density functional theory(DFT)calculations,the underlying reaction mechanisms were systematically revealed by investigating the reaction intermediates and products during the formation of the Kagome-honeycomb lattice.This work provides a promising pathway for the synthesis of Kagome-honeycomb lattices and offers a platform for exploring their novel physical properties.
