Anisotropy-Guided Enantiomeric Enhancement in AlanineUsing Far-UV Circularly Polarized Light
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All life on Earth is characterized by its asymmetry – both the genetic material and proteins are composed of homochiral monomers. Understanding how this molecular asymmetry initially arose is a key question related to the origins of life. Cometary ice simulations, l-enantiomeric enriched amino acids in meteorites and the detection of circularly polarized electromagnetic radiation in star-forming regions point to a possible interstellar/protostellar generation of stereochemical asymmetry. Based upon our recently recorded anisotropy spectra g(λ) of amino acids in the vacuum-UV range, we subjected amorphous films of racemic 13C-alanine to far-UV circularly polarized synchrotron radiation to probe the asymmetric photon-molecule interaction under interstellar conditions. Optical purities of up to 4 % were reached, which correlate with our theoretical predictions. Importantly, we show that chiral symmetry breaking using circularly polarized light is dependent on both the helicity and the wavelength of incident light. In order to predict such stereocontrol, time-dependent density functional theory was used to calculate anisotropy spectra. The calculated anisotropy spectra show good agreement with the experimental ones. The European Space Agency’s Rosetta mission, which successfully landed Philae on comet 67P/Churyumov-Gerasimenko on 12 November 2014, will investigate the configuration of chiral compounds and thereby obtain data that are to be interpreted in the context of the results presented here.
KeywordsAmino acids Anisotropy Homochirality Asymmetric photolysis Origins of life Chiral photons
- Brack A (1998) The molecular origins of life – assembling the pieces of the puzzle. Cambridge University Press, CambridgeGoogle Scholar
- Gaussian 03, Frisch MJ, Trucks GW, Schlegel HB, Scuseria GE, Robb MA, Cheeseman JR,Montgomery Jr. JA, Vreven T, Kudin KN, Burant JC, Millam JM, Iyengar SS, Tomasi J, Barone V, Mennucci B, Cossi M, Scalmani G, Rega N, Petersson GA et al. (2004) Gaussian, Inc., Wallingford CTGoogle Scholar
- Goesmann F, Raulin F, Bredehöft JH, Cabane M, Ehrenfreund P, MacDermott AJ, McKenna-Lawlor S, Meierhenrich UJ, Muñoz Caro GM, Szopa C, Sternberg R, Roll R, Thiemann WHP, Ulamec S (2014) COSAC prepares for sampling and in situ analysis of cometary matter from comet 67P/Churyumov-Gerasimenko. Planet Space Sci 103:318–330CrossRefGoogle Scholar
- Kuhn W (1929) Quantitative relationships for natural optical activity. Phys Chem B 4:14–36Google Scholar
- Meierhenrich UJ (2015) Comets and their origin – the tool to decipher a comet. Wiley-VCH, WeinheimGoogle Scholar
- Modica P, Meinert C, deMarcellus P, Nahon L, Meierhenrich UJ, Le Sergeant d’Hendecourt L (2014) Enantiomeric excesses induced in amino acids by ultraviolet circularly polarized light irradiation of extraterrestrial ice analogs: A possible source of asymmetry for prebiotic chemistry. Astrophys J 788:79 (11 pp)CrossRefGoogle Scholar
- Myrgorodska I, Meinert C, Martins Z, Le Sergeant d’Hendecourt L, Meierhenrich UJ (2014) Molecular chirality in meteorites and interstellar ices, and the chirality-experiment onboard ESA’s cometary rosetta mission. Angew Chem Int Ed 53, doi:10.1002/anie.201409354.
- Robitaille TP, Whitney AW, Indebetouw R, Wood K, Denzmore P (2006) Interpreting spectral enery distributions from young stellar objects. I. A grid of 200,000 YSO model SEDs. JApJS 167:256–285Google Scholar
- Szopa C, Sternberg R, Coscia D, Goesmann F, Gomes R, Legrand S, Jerome M, Meierhenrich UJ, Raulin F (2014) Gas chromatography for in situ analysis of a cometary nucleus V. Study of capillary columns robustness submitted to long term reduced environmental pressure conditions. J Chromatogr A 1368:211–216PubMedCrossRefGoogle Scholar