Chiral molecules and the electron spin

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The electron’s spin is essential to the stability of matter, and control over the spin opens up avenues for manipulating the properties of molecules and materials. The Pauli exclusion principle requires that two electrons in a single spatial eigenstate have opposite spins, and this fact dictates basic features of atomic states and chemical bond formation. The energy associated with interacting electron clouds changes with their relative spin orientation, and by manipulating the spin directions, one can guide chemical transformations. However, controlling the relative spin orientation of electrons located on two reactants (atoms, molecules or surfaces) has proved challenging. Recent developments based on the chiral-induced spin selectivity (CISS) effect show that the spin orientation is linked to molecular symmetry and can be controlled in ways not previously imagined. For example, the combination of chiral molecules and electron spin opens up a new approach to (enantio)selective chemistry. This Review describes the theoretical concepts underlying the CISS effect and illustrates its importance by discussing some of its manifestations in chemistry, biology and physics. Specifically, we discuss how the CISS effect allows for efficient long-range electron transfer in chiral molecules and how it affects biorecognition processes. Several applications of the effect are presented, and the importance of controlling relative spin orientations in multi-electron processes, such as electrochemical water splitting, is emphasized. We describe the enantiospecific interaction between ferromagnetic substrates and chiral molecules and how it enables the separation of enantiomers with ferromagnets. Lastly, we discuss the relevance of CISS effects to biological electron transfer, enantioselectivity and CISS-based spintronics applications.

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Fig. 1: Chiral-induced spin selectivity.
Fig. 2: The effect of chirality on electron transfer.
Fig. 3: CISS-based spintronic logic devices.
Fig. 4: Chiral-induced spin selectivity for photoelectrochemical water splitting.
Fig. 5: Chiral-induced spin selectivity effect and ferromagnetic substrates.
Fig. 6: Selective adsorption of dye-labelled dsDNA and cysteine.
Fig. 7: Chiral-induced spin selectivity for enantioseparation.


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R.N. and D.H.W. acknowledge support by the US Department of Energy (DOE), grant DE-SC0010662/ER46952. R.N., Y.P. and D.H.W. acknowledge support from the Templeton Foundation. R.N. and Y.P. acknowledge support from the Volkswagen Foundation. The authors thank H. Vega for the graphical work.

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Nature Reviews Chemistry thanks J. Robinson and the other anonymous reviewer(s) for their contribution to the peer review of this work.

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The authors contributed equally to all aspects of the article.

Correspondence to Ron Naaman.

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Kiralis Technology Ltd. was recently established and received a licence from The Hebrew University and the Weizmann Institute to commercialize the enantioseparation technology.

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Naaman, R., Paltiel, Y. & Waldeck, D.H. Chiral molecules and the electron spin. Nat Rev Chem 3, 250–260 (2019) doi:10.1038/s41570-019-0087-1

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