Chirality-Induced Electron Spin Polarization and Enantiospecific Response in Solid-State Cross-Polarization Nuclear Magnetic Resonance

Jose I. Santos, Iván Rivilla, Fernando P. Cossío, Jon M. Matxain, Marek Grzelczak, Shobeir K.S. Mazinani, Jesus M. Ugalde, Vladimiro Mujica

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8 Citations (Scopus)

Abstract

NMR-based techniques are supposed to be incapable of distinguishing pure crystalline chemical enantiomers. However, through systematic studies of cross-polarization magic angle spinning (CP-MAS) NMR in a series of amino acids, we have found a rather unexpected behavior in the intensity pattern of optical isomers in hydrogen/nitrogen nuclear polarization transfer that would allow the use of CP NMR as a nondestructive enantioselective detection technique. In all molecules considered, the d isomer yields higher intensity than the l form, while the chemical shift for all nuclei involved remains unchanged. We attribute this striking result to the onset of electron spin polarization, accompanying bond charge polarization through a chiral center, a secondary mechanism for polarization transfer that is triggered only in the CP experimental setup. Electron spin polarization is due to the chiral-induced spin selectivity effect (CISS), which creates an enantioselective response, analogous to the one involved in molecular recognition and enantiospecific separation with achiral magnetic substrates. This polarization influences the molecular magnetic environment, modifying the longitudinal relaxation time T1 of 1H, and ultimately provoking the observed asymmetry in the enantiomeric response.

Original languageEnglish
Pages (from-to)11426-11433
Number of pages8
JournalACS nano
Volume12
Issue number11
DOIs
Publication statusPublished - Nov 27 2018

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Keywords

  • CISS
  • CP-MAS
  • amino acids
  • chiral
  • enantiomers
  • solid-state NMR
  • spin

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

Cite this

Santos, J. I., Rivilla, I., Cossío, F. P., Matxain, J. M., Grzelczak, M., Mazinani, S. K. S., Ugalde, J. M., & Mujica, V. (2018). Chirality-Induced Electron Spin Polarization and Enantiospecific Response in Solid-State Cross-Polarization Nuclear Magnetic Resonance. ACS nano, 12(11), 11426-11433. https://doi.org/10.1021/acsnano.8b06467