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Cramer L, Larson A, Daniels AS, Sykes ECH, Gellman AJ. Molecular Origins of Chiral Amplification on an Achiral Surface: 2D Monolayers of Aspartic Acid on Cu(111). ACS NANO 2023; 17:5799-5807. [PMID: 36877997 PMCID: PMC10062026 DOI: 10.1021/acsnano.2c12312] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Accepted: 02/27/2023] [Indexed: 06/18/2023]
Abstract
Recent experiments have demonstrated an intriguing phenomenon in which adsorption of a nonracemic mixture of aspartic acid (Asp) enantiomers onto an achiral Cu(111) metal surface leads to autoamplification of surface enantiomeric excess, ees, to values well above those of the impinging gas mixtures, eeg. This is particularly interesting because it demonstrates that a slightly nonracemic mixture of enantiomers can be further purified simply by adsorption onto an achiral surface. In this work, we seek a deeper understanding of this phenomena and apply scanning tunneling microscopy to image the overlayer structures formed by mixed monolayers of d- and l-Asp on Cu(111) over the full range of surface enantiomeric excess; ees = -1 (pure l-Asp) through ees = 0 (racemic dl-Asp) to ees = 1 (pure d-Asp). Both enantiomers of three chiral monolayer structures are observed. One is a conglomerate (enantiomerically pure), another is a racemate (equimolar mixture of d- and l-Asp); however, the third structure accommodates both enantiomers in a 2:1 ratio. Such solid phases of enantiomer mixtures with nonracemic composition are rare in 3D crystals of enantiomers. We argue that, in 2D, the formation of chiral defects in a lattice of one enantiomer is easier than in 3D, simply because the stress associated with the chiral defect in a 2D monolayer of the opposite enantiomer can be dissipated by strain into the space above the surface.
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Affiliation(s)
- Laura
A. Cramer
- Department
of Chemistry, Tufts University, Medford, Massachusetts 02155-5813, United States
| | - Amanda Larson
- Department
of Chemistry, Tufts University, Medford, Massachusetts 02155-5813, United States
| | - Avery S. Daniels
- Department
of Chemistry, Tufts University, Medford, Massachusetts 02155-5813, United States
| | - E. Charles H. Sykes
- Department
of Chemistry, Tufts University, Medford, Massachusetts 02155-5813, United States
| | - Andrew J. Gellman
- Department of Chemical Engineering and W.E. Scott Institute for Energy Innovation, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
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2
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Radetic M, Gellman AJ. Enantiomer Adsorption in an Applied Magnetic Field: D‐ and L‐Aspartic Acid on Ni(100). Isr J Chem 2022. [DOI: 10.1002/ijch.202200028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Michael Radetic
- Department of Chemical Engineering Carnegie Mellon University 5000 Forbes Ave Pittsburgh PA 15213 USA
| | - Andrew J. Gellman
- Department of Chemical Engineering Carnegie Mellon University 5000 Forbes Ave Pittsburgh PA 15213 USA
- W.E. Scott Institute for Energy Innovation Carnegie Mellon University 5000 Forbes Ave Pittsburgh PA 15213 USA
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3
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Asymmetric azide-alkyne Huisgen cycloaddition on chiral metal surfaces. Commun Chem 2021; 4:51. [PMID: 36697612 PMCID: PMC9814088 DOI: 10.1038/s42004-021-00488-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 03/09/2021] [Indexed: 01/28/2023] Open
Abstract
Achieving fundamental understanding of enantioselective heterogeneous synthesis is marred by the permanent presence of multitudinous arrangements of catalytically active sites in real catalysts. In this study, we address this issue by using structurally comparatively simple, well-defined, and chiral intermetallic PdGa{111} surfaces as catalytic substrates. We demonstrate the impact of chirality transfer and ensemble effect for the thermally activated azide-alkyne Huisgen cycloaddition between 3-(4-azidophenyl)propionic acid and 9-ethynylphenanthrene on these threefold symmetric intermetallic surfaces under ultrahigh vacuum conditions. Specifically, we encounter a dominating ensemble effect for this reaction as on the Pd3-terminated PdGa{111} surfaces no stable heterocoupled structures are created, while on the Pd1-terminated PdGa{111} surfaces, the cycloaddition proceeds regioselectively. Moreover, we observe chirality transfer from the substrate to the reaction products, as they are formed enantioselectively on the Pd1-terminated PdGa{111} surfaces. Our results evidence a determinant ensemble effect and the immense potential of PdGa as asymmetric heterogeneous catalyst.
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Stolz S, Yakutovich AV, Prinz J, Dienel T, Pignedoli CA, Brune H, Gröning O, Widmer R. Near‐Enantiopure Trimerization of 9‐Ethynylphenanthrene on a Chiral Metal Surface. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202006844] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Samuel Stolz
- nanotech@surfaces Laboratory Empa—Swiss Federal Laboratories for Materials Science and Technology Überlandstrasse 129 8600 Dübendorf Switzerland
- Institute of Physics École Polytechnique Fédérale de Lausanne 1015 Lausanne Switzerland
| | - Aliaksandr V. Yakutovich
- nanotech@surfaces Laboratory Empa—Swiss Federal Laboratories for Materials Science and Technology Überlandstrasse 129 8600 Dübendorf Switzerland
- Present address: Laboratory of Molecular Simulation (LSMO) Ecole Polytechnique Fédérale de Lausanne (EPFL) Valais Rue de l'Industrie 17 1951 Sion Switzerland
| | - Jan Prinz
- nanotech@surfaces Laboratory Empa—Swiss Federal Laboratories for Materials Science and Technology Überlandstrasse 129 8600 Dübendorf Switzerland
- Institute of Physics École Polytechnique Fédérale de Lausanne 1015 Lausanne Switzerland
| | - Thomas Dienel
- nanotech@surfaces Laboratory Empa—Swiss Federal Laboratories for Materials Science and Technology Überlandstrasse 129 8600 Dübendorf Switzerland
- Present address: Department of Materials Science and Engineering Cornell University Ithaca NY 14853 USA
| | - Carlo A. Pignedoli
- nanotech@surfaces Laboratory Empa—Swiss Federal Laboratories for Materials Science and Technology Überlandstrasse 129 8600 Dübendorf Switzerland
| | - Harald Brune
- Institute of Physics École Polytechnique Fédérale de Lausanne 1015 Lausanne Switzerland
| | - Oliver Gröning
- nanotech@surfaces Laboratory Empa—Swiss Federal Laboratories for Materials Science and Technology Überlandstrasse 129 8600 Dübendorf Switzerland
| | - Roland Widmer
- nanotech@surfaces Laboratory Empa—Swiss Federal Laboratories for Materials Science and Technology Überlandstrasse 129 8600 Dübendorf Switzerland
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5
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Stolz S, Yakutovich AV, Prinz J, Dienel T, Pignedoli CA, Brune H, Gröning O, Widmer R. Near-Enantiopure Trimerization of 9-Ethynylphenanthrene on a Chiral Metal Surface. Angew Chem Int Ed Engl 2020; 59:18179-18183. [PMID: 32589816 DOI: 10.1002/anie.202006844] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Indexed: 11/08/2022]
Abstract
Enantioselectivity in heterogeneous catalysis strongly depends on the chirality transfer between catalyst surface and all reactants, intermediates, and the product along the reaction pathway. Herein we report the first enantioselective on-surface synthesis of molecular structures from an initial racemic mixture and without the need of enantiopure modifier molecules. The reaction consists of a trimerization via an unidentified bonding motif of prochiral 9-ethynylphenanthrene (9-EP) upon annealing to 500 K on the chiral Pd3 -terminated PdGa{111} surfaces into essentially enantiopure, homochiral 9-EP propellers. The observed behavior strongly contrasts the reaction of 9-EP on the chiral Pd1 -terminated PdGa{111} surfaces, where 9-EP monomers that are in nearly enantiopure configuration, dimerize without enantiomeric excess. Our findings demonstrate strong chiral recognition and a significant ensemble effect in the PdGa system, hence highlighting the huge potential of chiral intermetallic compounds for enantioselective synthesis and underlining the importance to control the catalytically active sites at the atomic level.
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Affiliation(s)
- Samuel Stolz
- nanotech@surfaces Laboratory, Empa-Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600, Dübendorf, Switzerland.,Institute of Physics, École Polytechnique Fédérale de Lausanne, 1015, Lausanne, Switzerland
| | - Aliaksandr V Yakutovich
- nanotech@surfaces Laboratory, Empa-Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600, Dübendorf, Switzerland.,Present address: Laboratory of Molecular Simulation (LSMO), Ecole Polytechnique Fédérale de Lausanne (EPFL) Valais, Rue de l'Industrie 17, 1951, Sion, Switzerland
| | - Jan Prinz
- nanotech@surfaces Laboratory, Empa-Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600, Dübendorf, Switzerland.,Institute of Physics, École Polytechnique Fédérale de Lausanne, 1015, Lausanne, Switzerland
| | - Thomas Dienel
- nanotech@surfaces Laboratory, Empa-Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600, Dübendorf, Switzerland.,Present address: Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Carlo A Pignedoli
- nanotech@surfaces Laboratory, Empa-Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600, Dübendorf, Switzerland
| | - Harald Brune
- Institute of Physics, École Polytechnique Fédérale de Lausanne, 1015, Lausanne, Switzerland
| | - Oliver Gröning
- nanotech@surfaces Laboratory, Empa-Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600, Dübendorf, Switzerland
| | - Roland Widmer
- nanotech@surfaces Laboratory, Empa-Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600, Dübendorf, Switzerland
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Shukla N, Gellman AJ. Chiral metal surfaces for enantioselective processes. NATURE MATERIALS 2020; 19:939-945. [PMID: 32747699 DOI: 10.1038/s41563-020-0734-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Accepted: 06/15/2020] [Indexed: 05/24/2023]
Abstract
Chiral surfaces are critical components of enantioselective heterogeneous processes such as those used to prepare enantiomerically pure pharmaceuticals. While the majority of chiral surfaces in practical use are based on achiral materials whose surfaces have been modified with enantiomerically pure chiral adsorbates, there are many inorganic materials with valuable surface properties that could be rendered enantiospecific, if their surfaces were intrinsically chiral. This Perspective discusses recent developments in the fabrication of intrinsically chiral surfaces exhibiting enantiospecific adsorption, surface chemistry and electron emission. We propose possible paths to the scalable fabrication of high-surface-area, enantiomerically pure surfaces and discuss opportunities for future progress.
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Affiliation(s)
- Nisha Shukla
- Institute for Complex Engineered Systems, Carnegie Mellon University, Pittsburgh, PA, USA
- Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Andrew J Gellman
- Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA.
- W.E. Scott Institute for Energy Innovation, Carnegie Mellon University, Pittsburgh, PA, USA.
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Dutta S, Gellman AJ. Enantiospecific equilibrium adsorption and chemistry of
d
‐/
l
‐proline mixtures on chiral and achiral Cu surfaces. Chirality 2019; 32:200-214. [DOI: 10.1002/chir.23153] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 09/13/2019] [Accepted: 09/14/2019] [Indexed: 11/06/2022]
Affiliation(s)
- Soham Dutta
- Department of Chemical Engineering Carnegie Mellon University Pittsburgh Pennsylvania
| | - Andrew J. Gellman
- Department of Chemical Engineering Carnegie Mellon University Pittsburgh Pennsylvania
- W.E. Scott Institute for Energy Innovation Carnegie Mellon University Pittsburgh Pennsylvania
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8
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Karagoz B, Reinicker A, Gellman AJ. Kinetics and Mechanism of Aspartic Acid Adsorption and Its Explosive Decomposition on Cu(100). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:2925-2933. [PMID: 30681872 DOI: 10.1021/acs.langmuir.8b03482] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The mechanism and kinetics of aspartic acid (Asp, HO2CCH(NH2)CH2CO2H) decomposition on Cu(100) have been studied using X-ray photoemission spectroscopy and temperature-programmed reaction spectroscopy. We investigate the Asp decomposition mechanism in detail using unlabeled d-Asp and isotopically labeled l-Asp-4-13C (HO2CCH(NH2)CH213CO2H), l-Asp- d7 (DO2CCD(ND2)CD2CO2D), l-Asp-2,3,3- d3 (HO2CCD(NH2)CD2CO2H), and l-Asp-15N-2,3,3- d3 (HO2CCD(15NH2)CD2CO2H). The monolayer of Asp adsorbed on the Cu(100) surface is in a doubly deprotonated bi-aspartate form (-O2CCH(NH2)CH2CO2-). During heating, Asp decomposes on Cu(100) with kinetics consistent with a vacancy-mediated explosion mechanism. The mechanistic steps yield CO2 by sequential cleavage of the C3-C4 and C1-C2 bonds, and N≡CCH3 and H2 via decomposition of the remaining CH(NH2)CH2 intermediate. Deuterium labeling has been used to demonstrate that scrambling of H(D) occurs during the decomposition to acetonitrile of the CD(NH2)CD2 intermediate formed by decarboxylation of l-Asp-2,3,3- d3 and l-Asp-15N-2,3,3- d3.
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Affiliation(s)
- Burcu Karagoz
- Department of Chemical Engineering , Carnegie Mellon University , 5000 Forbes Avenue , Pittsburgh , Pennsylvania 15213 , United States
| | - Aaron Reinicker
- Department of Chemical Engineering , Carnegie Mellon University , 5000 Forbes Avenue , Pittsburgh , Pennsylvania 15213 , United States
| | - Andrew J Gellman
- Department of Chemical Engineering , Carnegie Mellon University , 5000 Forbes Avenue , Pittsburgh , Pennsylvania 15213 , United States
- W.E. Scott Institute for Energy Innovation , 5000 Forbes Avenue , Pittsburgh , Pennsylvania 15213 , United States
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10
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Dutta S, Gellman AJ. Enantiomer surface chemistry: conglomerate versus racemate formation on surfaces. Chem Soc Rev 2018; 46:7787-7839. [PMID: 29165467 DOI: 10.1039/c7cs00555e] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Research on surface chirality is motivated by the need to develop functional chiral surfaces for enantiospecific applications. While molecular chirality in 3D has been the subject of study for almost two centuries, many aspects of 2D chiral surface chemistry have yet to be addressed. In 3D, racemic mixtures of chiral molecules tend to aggregate into racemate (molecularly heterochiral) crystals much more frequently than conglomerate (molecularly homochiral) crystals. Whether chiral adsorbates on surfaces preferentially aggregate into heterochiral rather than homochiral domains (2D crystals or clusters) is not known. In this review, we have made the first attempt to answer the following question based on available data: in 2D racemic mixtures adsorbed on surfaces, is there a clear preference for homochiral or heterochiral aggregation? The current hypothesis is that homochiral packing is preferred on surfaces; in contrast to 3D where heterochiral packing is more common. In this review, we present a simple hierarchical scheme to categorize the chirality of adsorbate-surface systems. We then review the body of work using scanning tunneling microscopy predominantly to study aggregation of racemic adsorbates. Our analysis of the existing literature suggests that there is no clear evidence of any preference for either homochiral or heterochiral aggregation at the molecular level by chiral and prochiral adsorbates on surfaces.
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Affiliation(s)
- Soham Dutta
- Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
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11
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Abstract
In the present review we survey the main advances made in recent years on the understanding of chemical chirality at solid surfaces. Chirality is an important topic, made particularly relevant by the homochiral nature of the biochemistry of life on Earth, and many chiral chemical reactions involve solid surfaces. Here we start our discussion with a description of surface chirality and of the different ways that chirality can be bestowed on solid surfaces. We then expand on the studies carried out to date to understand the adsorption of chiral compounds at a molecular level. We summarize the work published on the adsorption of pure enantiomers, of enantiomeric mixtures, and of prochiral molecules on chiral and achiral model surfaces, especially on well-defined metal single crystals but also on other flat substrates such as highly ordered pyrolytic graphite. Several phenomena are identified, including surface reconstruction and chiral imprinting upon adsorption of chiral agents, and the enhancement or suppression of enantioselectivity seen in some cases upon adsorption of enantiomixtures of chiral compounds. The possibility of enhancing the enantiopurity of adsorbed layers upon the addition of chiral seeds and the so-called "sergeants and soldiers" phenomenon are presented. Examples are provided where the chiral behavior has been associated with either thermodynamic or kinetic driving forces. Two main approaches to the creation of enantioselective surface sites are discussed, namely, via the formation of supramolecular chiral ensembles made out of small chiral adsorbates, and by adsorption of more complex chiral molecules capable of providing suitable chiral environments for reactants by themselves, via the formation of individual adsorbate:modifier adducts on the surface. Finally, a discussion is offered on the additional effects generated by the presence of the liquid phase often required in practical applications such as enantioselective crystallization, chiral chromatography, and enantioselective catalysis.
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Affiliation(s)
- Francisco Zaera
- Department of Chemistry and UCR Center for Catalysis, University of California, Riverside, CA 92521, USA.
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