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Ernst KH. Helicenes on Surfaces: Stereospecific On-Surface Chemistry, Single Enantiomorphism, and Electron Spin Selectivity. Chirality 2024; 36:e23706. [PMID: 39077832 DOI: 10.1002/chir.23706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2024] [Revised: 07/07/2024] [Accepted: 07/09/2024] [Indexed: 07/31/2024]
Abstract
Helicenes represent an important class of chiral organic material with promising optoelectronic properties. Hence, functionalization of surfaces with helicenes is a key step towards new organic material devices. This review presents different aspects of adsorption and modification of metal surfaces with different helicene species. Topics addressed are chiral crystallization, that is, 2D conglomerate versus racemate crystallization, breaking of mirror-symmetry in racemates, chirality-induced spin selectivity, and stereoselective on-surface chemistry.
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Affiliation(s)
- Karl-Heinz Ernst
- Molecular Surface Science, Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
- Nanosurf Lab, Institute of Physics of the Czech Academy of Sciences, Prague 6, Czech Republic
- Department of Chemistry, University of Zurich, Zürich, Switzerland
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2
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Martin K, Aharon T, Mastropasqua Talamo M, Hauser A, Bürgi T, Vanthuyne N, Caricato M, Avarvari N. Helicene Appended Benzothiadiazoles as Chiral Emitters. Chemistry 2024; 30:e202401413. [PMID: 38770893 DOI: 10.1002/chem.202401413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Revised: 05/20/2024] [Accepted: 05/21/2024] [Indexed: 05/22/2024]
Abstract
A homologous series of 4,7-bis(aryl) substituted benzothiadiazole (BTD) compounds, containing the helicenic derivatives bis([4]helicene), bis([5]helicene) and bis([6]helicene), have been prepared upon a double Suzuki coupling between 3,6-bis(pinacolyl-borane)-BTD and the corresponding bromo-aryl precursors. The single crystal X-ray structure of the bis([4]helicene) compound shows the existence of both helicities (M) and (P) on the same molecule. All the compounds of the series are highly emissive in solution, with quantum yields of the emission ranging from 50 to 91 %. The enantiopure compounds (M,M) and (P,P) for the BTD-bis([6]helicene) have been prepared from the corresponding enantiopure 2-bromo-[6]helicene precursors. Their chiroptical properties have been investigated in correlation with density functional theory (DFT) calculations, which allowed to confidently assign the absolute configuration of the helicene arms and to characterize the different electronic transitions, including the low energy charge transfer excitation from helicenes to BTD. The enantiomerically pure fluorophores (M,M)- and (P,P)-BTD-bis([6]helicene), which exist in solution as two main conformers, according to the DFT calculations, show CPL activity in solution, with glum factors of ≈1.7×10-3 at λem=525 nm, and also in the solid state, with glum factors of ≈1.2×10-3 in spite of the strong decrease of the quantum efficiency.
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Affiliation(s)
- Kévin Martin
- Univ Angers, CNRS, MOLTECH-Anjou SFR MATRIX, F-49000, Angers, France
| | - Tal Aharon
- Department of Chemistry, University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas, 66045, United States of America
- TetraScience, 294 Washington St, Boston, MA 02108, United States of America
| | | | - Andreas Hauser
- Department of Physical Chemistry, University of Geneva, 30 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland
| | - Thomas Bürgi
- Department of Physical Chemistry, University of Geneva, 30 Quai Ernest Ansermet, CH-1211, Geneva, Switzerland
| | - Nicolas Vanthuyne
- Aix Marseille Univ, CNRS, Centrale Marseille UAR, 1739, FSCM, Chiropole, Marseille, France
| | - Marco Caricato
- Department of Chemistry, University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas, 66045, United States of America
| | - Narcis Avarvari
- Univ Angers, CNRS, MOLTECH-Anjou SFR MATRIX, F-49000, Angers, France
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Peng X, Zhang Y, Liu X, Qian Y, Ouyang Z, Kong H. From Short- to Long-Range Chiral Recognition on Surfaces: Chiral Assembly and Synthesis. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2307171. [PMID: 38054810 DOI: 10.1002/smll.202307171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Revised: 11/13/2023] [Indexed: 12/07/2023]
Abstract
Research on chiral behaviors of small organic molecules at solid surfaces, including chiral assembly and synthesis, can not only help unravel the origin of the chiral phenomenon in biological/chemical systems but also provide promising strategies to build up unprecedented chiral surfaces or nanoarchitectures with advanced applications in novel nanomaterials/nanodevices. Understanding how molecular chirality is recognized is considered to be a mandatory basis for such studies. In this review, a series of recent studies in chiral assembly and synthesis at well-defined metal surfaces under ultra-high vacuum conditions are outlined. More importantly, the intrinsic mechanisms of chiral recognition are highlighted, including short/long-range chiral recognition in chiral assembly and two main strategies to steer the reaction pathways and modulate selective synthesis of specific chiral products on surfaces.
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Affiliation(s)
- Xinchen Peng
- Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, P. R. China
| | - Yinhui Zhang
- Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, P. R. China
| | - Xinbang Liu
- Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, P. R. China
| | - Yinyue Qian
- Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, P. R. China
| | - Zuoling Ouyang
- Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, P. R. China
| | - Huihui Kong
- Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, P. R. China
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Baljozović M, Arnoldi B, Grass S, Lacour J, Aeschlimann M, Stadtmüller B, Ernst KH. Spin- and angle-resolved photoemission spectroscopy study of heptahelicene layers on Cu(111) surfaces. J Chem Phys 2023; 159:044701. [PMID: 37486054 DOI: 10.1063/5.0156581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 06/29/2023] [Indexed: 07/25/2023] Open
Abstract
It has been demonstrated previously that electrons interact differently with chiral molecules depending on their polarization. For enantiomeric pure monolayers of heptahelicene, opposite asymmetries in spin polarization were reported and attributed to the so-called chirality-induced spin selectivity effect. However, these promising proof-of-concept photoemission experiments lack the angular and energy resolution that could provide the necessary insights into the mechanism of this phenomenon. In order to fill in the missing gaps, we provide a detailed spin- and angle-resolved photoemission spectroscopy study of heptahelicene layers on a Cu(111) substrate. Throughout the large accessible energy and angle range, no chirality induced spin asymmetry in photoemission could be observed. Possible reasons for the absence of signatures of the spin-dependent electron transmission through the chiral molecular layer are briefly discussed.
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Affiliation(s)
- M Baljozović
- Molecular Surface Science Group, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
| | - B Arnoldi
- Department of Physics and Research Center OPTIMAS, Rheinland-Pfälzische Technische Universität (RPTU) Kaiserslautern-Landau, 67663 Kaiserslautern, Germany
| | - S Grass
- Department of Organic Chemistry, University of Geneva, 1211 Geneva 4, Switzerland
| | - J Lacour
- Department of Organic Chemistry, University of Geneva, 1211 Geneva 4, Switzerland
| | - M Aeschlimann
- Department of Physics and Research Center OPTIMAS, Rheinland-Pfälzische Technische Universität (RPTU) Kaiserslautern-Landau, 67663 Kaiserslautern, Germany
| | - B Stadtmüller
- Department of Physics and Research Center OPTIMAS, Rheinland-Pfälzische Technische Universität (RPTU) Kaiserslautern-Landau, 67663 Kaiserslautern, Germany
- Institute of Physics Johannes Gutenberg-University Mainz, 55099 Mainz, Germany
| | - K-H Ernst
- Molecular Surface Science Group, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
- Nanosurf Laboratory, Institute of Physics, The Czech Academy of Sciences, 16200 Prague, Czech Republic
- Department of Chemistry, University of Zurich, 8057 Zürich, Switzerland
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Liu JW, Wang Y, Kang LX, Zhao Y, Xing GY, Huang ZY, Zhu YC, Li DY, Liu PN. Two-Dimensional Crystal Transition from Radialene to Cumulene on Ag(111) via Retro-[2 + 1] Cycloaddition. J Am Chem Soc 2023. [PMID: 37289993 DOI: 10.1021/jacs.3c00962] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Two-dimensional (2D) crystal-to-crystal transition is an important method in crystal engineering because of its ability to directly create diverse crystal materials from one crystal. However, steering a 2D single-layer crystal-to-crystal transition on surfaces with high chemo- and stereoselectivity under ultra-high vacuum conditions is a great challenge because the transition is a complex dynamic process. Here, we report a highly chemoselective 2D crystal transition from radialene to cumulene with retention of stereoselectivity on Ag(111) via retro-[2 + 1] cycloaddition of three-membered carbon rings and directly visualize the transition process involving a stepwise epitaxial growth mechanism by the combination of scanning tunneling microscopy and non-contact atomic force microscopy. Using progression annealing, we found that isocyanides on Ag(111) at a low annealing temperature underwent sequential [1 + 1 + 1] cycloaddition and enantioselective molecular recognition based on C-H···Cl hydrogen bonding interactions to form 2D triaza[3]radialene crystals. In contrast, a higher annealing temperature induced the transformation of triaza[3]radialenes to generate trans-diaza[3]cumulenes, which were further assembled into 2D cumulene-based crystals through twofold N-Ag-N coordination and C-H···Cl hydrogen bonding interactions. By combining the observed distinct transient intermediates and density functional theory calculations, we demonstrate that the retro-[2 + 1] cycloaddition reaction proceeds via the ring opening of a three-membered carbon ring, sequential dechlorination/hydrogen passivation, and deisocyanation. Our findings provide new insights into the growth mechanism and dynamics of 2D crystals and have implications for controllable crystal engineering.
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Affiliation(s)
- Jian-Wei Liu
- Key Laboratory for Advanced Materials and Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, State Key Laboratory of Chemical Engineering, School of Chemistry and Molecular Engineering, East China University of Science & Technology, 130 Meilong Road, Shanghai 200237, China
| | - Ying Wang
- Key Laboratory for Advanced Materials and Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, State Key Laboratory of Chemical Engineering, School of Chemistry and Molecular Engineering, East China University of Science & Technology, 130 Meilong Road, Shanghai 200237, China
| | - Li-Xia Kang
- Key Laboratory for Advanced Materials and Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, State Key Laboratory of Chemical Engineering, School of Chemistry and Molecular Engineering, East China University of Science & Technology, 130 Meilong Road, Shanghai 200237, China
| | - Yan Zhao
- Key Laboratory for Advanced Materials and Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, State Key Laboratory of Chemical Engineering, School of Chemistry and Molecular Engineering, East China University of Science & Technology, 130 Meilong Road, Shanghai 200237, China
| | - Guang-Yan Xing
- Key Laboratory for Advanced Materials and Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, State Key Laboratory of Chemical Engineering, School of Chemistry and Molecular Engineering, East China University of Science & Technology, 130 Meilong Road, Shanghai 200237, China
| | - Zheng-Yang Huang
- Key Laboratory for Advanced Materials and Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, State Key Laboratory of Chemical Engineering, School of Chemistry and Molecular Engineering, East China University of Science & Technology, 130 Meilong Road, Shanghai 200237, China
| | - Ya-Cheng Zhu
- Key Laboratory for Advanced Materials and Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, State Key Laboratory of Chemical Engineering, School of Chemistry and Molecular Engineering, East China University of Science & Technology, 130 Meilong Road, Shanghai 200237, China
| | - Deng-Yuan Li
- Key Laboratory for Advanced Materials and Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, State Key Laboratory of Chemical Engineering, School of Chemistry and Molecular Engineering, East China University of Science & Technology, 130 Meilong Road, Shanghai 200237, China
| | - Pei-Nian Liu
- Key Laboratory for Advanced Materials and Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, State Key Laboratory of Chemical Engineering, School of Chemistry and Molecular Engineering, East China University of Science & Technology, 130 Meilong Road, Shanghai 200237, China
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