Enantiomer surface chemistry: conglomerate versus racemate formation on surfaces
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...
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| Published in | Chemical Society reviews Vol. 46; no. 24; pp. 7787 - 7839 |
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| Main Authors | , |
| Format | Journal Article |
| Language | English |
| Published |
England
Royal Society of Chemistry
11.12.2017
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| Subjects | |
| Online Access | Get full text |
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| Summary: | 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.
A comprehensive review classifying chirality expressed on surfaces and, by surveying available literature, determining the tendency for conglomerate
vs.
racemate formation on surfaces. |
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| Bibliography: | Andrew Gellman is the Thomas Lord Professor of Chemical Engineering at Carnegie Mellon University. He received a BS in Chemistry from the California Institute of Technology and a PhD in Chemistry from the University of California at Berkeley. His research expertise is in the field of surface science and surface chemistry with emphasis on catalysis, corrosion, chirality and enantioselectivity. In addition, his group has developed of tools and methods for high throughput study of alloy surfaces spanning alloy composition space and for studies of structure sensitive properties of crystalline surfaces spanning surface orientation space. Soham Dutta is a PhD student in the Department of Chemical Engineering at Carnegie Mellon University in Pittsburgh, Pennsylvania, USA. He received his Bachelor of Engg. at Siddaganga Institute of Technology, Tumkur, India and his Master of Science at Carnegie Mellon University. He is currently a member of the Catalysis and Surface Science laboratory and is studying decomposition and aggregation of chiral molecules on single crystal metal surfaces. Fundamental understanding of such phenomena has applications in enantiomer separation, enantioselective catalysis and supramolecular chirality. ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 14 ObjectType-Review-3 content type line 23 USDOE Office of Science (SC) SC0008703 |
| ISSN: | 0306-0012 1460-4744 1460-4744 |
| DOI: | 10.1039/c7cs00555e |