so has the same status as circularly polarized light and the electroweak interaction in its ability to induce absolute enantioselection4,5. These are currently the most favoured explanations for the homochirality of life, and enantioselective photochemistry with circularly polarized light has already been observed experimentally. On both experimental and theoretical grounds, we now have to seriously consider magnetochiral photochemistry in discussions of the possible origins of biological homochirality10. This is especially pertinent to fashionable theories suggesting that complex organic molecules could evolve in the ice mantles of dust grains in interstellar space11, because magnetic fields and unpolarized light are more common in the cosmos than circularly polarized light.
Furthermore, cosmic magnetic fields lead to partial orientation of the dust grains12, which may enhance any associated enantioselective chemistry. n Laurence D. Barron is in the Department of Chemistry, University of Glasgow, Glasgow G12 8QQ, UK.
1. Rikken, G. L. J. A. & Raupach, E. Nature 405, 932-935 (2000).
2. Mason, S. F. Nature 311, 19-23 (1984).
3. Lord Kelvin Baltimore Lectures (Clay, London, 1904).
4. Avalos, M. et al. Chem. Rev. 98, 2391-2404 (1998).
5. Feringa, B. L. & van Delden, R. A. Angew. Chem. Int. Edn Engl. 38, 3418-3438 (1999).
6. Wagnière, G. & Meier, A. Chem. Phys. Lett. 93, 78-81 (1982).
7. Barron, L. D. & Vrbancich, J. Mol. Phys. 51, 715-730 (1984).
8. Rikken, G. L. J. A. & Raupach, E. Nature 390, 493-494 (1997).