Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Amplification of chirality in two-dimensional enantiomorphous lattices

Abstract

The concept of chirality dates back to 1848, when Pasteur manually separated left-handed from right-handed sodium ammonium tartrate crystals1. Crystallization is still an important means for separating chiral molecules into their two different mirror-image isomers (enantiomers)2, yet remains poorly understood3. For example, there are no firm rules to predict whether a particular pair of chiral partners will follow the behaviour of the vast majority of chiral molecules and crystallize together as racemic crystals4, or as separate enantiomers. A somewhat simpler and more tractable version of this phenomenon is crystallization in two dimensions, such as the formation of surface structures by adsorbed molecules. The relatively simple spatial molecular arrangement of these systems makes it easier to study the effects of specific chiral interactions5; moreover, chiral assembly and recognition processes can be observed directly and with molecular resolution using scanning tunnelling microscopy6,7,8,9. The enantioseparation of chiral molecules in two dimensions is expected to occur more readily because planar confinement excludes some bulk crystal symmetry elements and enhances chiral interactions10,11; however, many surface structures have been found to be racemic12,13,14,15,16,17,18. Here we show that the chiral hydrocarbon heptahelicene on a Cu(111) surface does not undergo two-dimensional spontaneous resolution into enantiomers19, but still shows enantiomorphism on a mesoscopic length scale that is readily amplified. That is, we observe formation of racemic heptahelicene domains with non-superimposable mirror-like lattice structures, with a small excess of one of the heptahelicene enantiomers suppressing the formation of one domain type. Similar to the induction of homochirality in achiral enantiomorphous monolayers20 by a chiral modifier, a small enantiomeric excess suffices to ensure that the entire molecular monolayer consists of domains having only one of two possible, non-superimposable, mirror-like lattice structures.

Your institute does not have access to this article

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.

$32.00

All prices are NET prices.

Figure 1: Enantiomorphous domains of racemic heptahelicene on Cu(111).
Figure 2: Identification of enantiomeric composition.
Figure 3: Nonlinear amplification of chirality in non-racemic layers.
Figure 4: Illustration of the energetic contributions driving the chiral amplification mechanism.

References

  1. Pasteur, L. Recherches sur les relations qui peuvent exister entre la forme crystalline et la composition chimique, et le sens de la polarisation rotatoire. Ann. Chim. Phys. 24, 442–459 (1848)

    Google Scholar 

  2. Sheldon, R. A. in Chiral Technologies: Industrial Synthesis of Optically Active Compounds 173–204 (M. Dekker, New York, 1993)

    Google Scholar 

  3. Addadi, L. & Weiner, S. Crystals, asymmetry and life. Nature 411, 753–754 (2001)

    ADS  CAS  Article  Google Scholar 

  4. Jacques, J., Collet, A. & Wilen, S. H. in Enantiomers, Racemates and Resolution (Wiley, New York, 1981)

    Google Scholar 

  5. Maddox, J. Racemization rationalized. Nature 341, 101 (1989)

    ADS  Article  Google Scholar 

  6. De Feyter, S. & De Schryver, F. C. Two-dimensional supramolecular self-assembly probed by scanning tunneling microscopy. Chem. Soc. Rev. 32, 139–150 (2003)

    CAS  Article  Google Scholar 

  7. Ortega Lorenzo, M., Baddeley, C. J., Muryn, C. & Raval, R. Extended surface chirality from supramolecular assemblies of adsorbed chiral molecules. Nature 404, 376–379 (2000)

    ADS  Article  Google Scholar 

  8. Kühnle, A., Linderoth, T. R., Hammer, B. & Besenbacher, F. Chiral recognition in dimerization of adsorbed cysteine observed by scanning tunnelling microscopy. Nature 415, 891–893 (2002)

    ADS  Article  Google Scholar 

  9. Chen, Q. & Richardson, N. V. Enantiomeric interactions between nucleic acid bases and amino acids on solid surfaces. Nature Mater. 2, 324–328 (2003)

    ADS  CAS  Article  Google Scholar 

  10. Kuzmenko, I. et al. Aspects of spontaneous separation of enantiomers in two- and three-dimensional crystals. Chirality 10, 415–424 (1998)

    CAS  Article  Google Scholar 

  11. Perez-Garcia, L. & Amabilino, D. B. Spontaneous resolution under supramolecular control. Chem. Soc. Rev. 31, 342–356 (2002)

    CAS  Article  Google Scholar 

  12. De Feyter, S. et al. Homo- and heterochiral supramolecular tapes from achiral, enantiopure, and racemic promesogenic formamides. Angew. Chem. Int. Edn Engl. 40, 3217–3220 (2001)

    CAS  Article  Google Scholar 

  13. Romer, S., Behzadi, B., Fasel, R. & Ernst, K.-H. Homochiral conglomerates and racemic crystals in two dimensions: Tartaric acid on Cu(110). Chem. Eur. J. 11, 4149–4154 (2005)

    CAS  Article  Google Scholar 

  14. Cai, Y. & Bernasek, S. L. Chiral pair monolayer adsorption of iodine-substituted octadecanol molecules on graphite. J. Am. Chem. Soc. 125, 1655–1659 (2003)

    CAS  Article  Google Scholar 

  15. Wie, Y., Kannappan, K., Flynn, G. W. & Zimmt, M. B. Scanning tunneling microscopy of prochiral anthracene derivatives on graphite: chain length effects on monolayer morphology. J. Am. Chem. Soc. 126, 5318–5322 (2004)

    Article  Google Scholar 

  16. Vidal, F. et al. Chiral phase transition in two-dimensional supramolecular assemblies of prochiral molecules. J. Am. Chem. Soc. 127, 10101–10106 (2005)

    CAS  Article  Google Scholar 

  17. Cai, Y. & Bernasek, S. L. Structures formed by the chiral assembly of racemic mixtures of enantiomers: iodination products of elaidic and oleic acids. J. Phys. Chem. B 109, 4514–4519 (2005)

    CAS  Article  Google Scholar 

  18. Böhringer, M., Schneider, W.-D. & Berndt, R. Real space observation of a chiral phase transition in a two-dimensional organic layer. Angew. Chem. Int. Edn Engl. 39, 792–795 (2000)

    Article  Google Scholar 

  19. Ernst, K.-H., Kuster, Y., Fasel, R., Müller, M. & Ellerbeck, U. Two-dimensional separation of [7]helicene enantiomers on Cu(111). Chirality 13, 675–678 (2001)

    CAS  Article  Google Scholar 

  20. Parschau, M., Romer, S. & Ernst, K.-H. Induction of homochirality in achiral enantiomorphous monolayers. J. Am. Chem. Soc. 126, 15398–15399 (2004)

    CAS  Article  Google Scholar 

  21. Fasel, R., Parschau, M. & Ernst, K.-H. Chirality transfer from single molecules into self-assembled monolayers. Angew. Chem. Int. Edn Engl. 42, 5178–5181 (2003)

    CAS  Article  Google Scholar 

  22. Barlow, S. M. & Raval, R. Complex molecules at metal surfaces: bonding, organisation and chirality. Surf. Sci. Rep. 50, 201–341 (2003)

    ADS  CAS  Article  Google Scholar 

  23. Green, M. M. et al. The macromolecular route to chiral amplification. Angew. Chem. Int. Edn Engl. 38, 3138–3154 (1999)

    CAS  Article  Google Scholar 

Download references

Acknowledgements

This work was supported by the Swiss National Science Foundation (SNF). We thank O. Gröning for writing the software to simulate STM images and U. Ellerbeck for the [7]H synthesis.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Karl-Heinz Ernst.

Ethics declarations

Competing interests

Reprints and permissions information is available at npg.nature.com/reprintsandpermissions. The authors declare no competing financial interests.

Supplementary information

Supplementary Methods

This file describes the experimental procedures and gives detail on the molecular mechanics calculations. (PDF 149 kb)

Supplementary Figure 1

This figure describes the segregation of enantiomeric excess to steps and into residual areas. (PDF 124 kb)

Supplementary Figure 2

This figure describes the calculated energy cost when single M- or P- heptahelicene molecules in λ and ρ domains are substituted by opposite enantiomers. (PDF 205 kb)

Supplementary Figure 3

This figure describes the higher energy content of mirror domain boundaries with respect to rotational domain boundaries. (PDF 453 kb)

Supplementary Figure 4

This figure describes the calculation of the energy at the interface between a l domain edge and excess molecules of different handedness. (PDF 156 kb)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Fasel, R., Parschau, M. & Ernst, KH. Amplification of chirality in two-dimensional enantiomorphous lattices. Nature 439, 449–452 (2006). https://doi.org/10.1038/nature04419

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nature04419

Further reading

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing