Spin Selectivity in Chiral Linked Systems

Aleksandra A Ageeva; Ekaterina A Khramtsova; Ilya M Magin; Denis A Rychkov; Peter A Purtov; Miguel A Miranda; Tatyana V Leshina

doi:10.1002/chem.201705863

Spin Selectivity in Chiral Linked Systems

Chemistry. 2018 Mar 12;24(15):3882-3892. doi: 10.1002/chem.201705863. Epub 2018 Feb 19.

Authors

Aleksandra A Ageeva¹, Ekaterina A Khramtsova^{1

2}, Ilya M Magin¹, Denis A Rychkov^{2

3}, Peter A Purtov^{1

2}, Miguel A Miranda⁴, Tatyana V Leshina¹

Affiliations

¹ Laboratory of Magnetic Phenomena, Voevodsky Institute of Chemical Kinetics and Combustion SB RAS, Institutskaya 3, 630090, Novosibirsk, Russia.
² Novosibirsk State University, Pirogova 2, 630090, Novosibirsk, Russia.
³ Institute of Solid State Chemistry and Mechanochemistry SB RAS, Kutateladze 18, 630128, Novosibirsk, Russia.
⁴ Departamento de Química/Instituto de Tecnología Química UPV-CSIC, Universitat Politècnica de València, Camino de Vera s/n, 46022, Valencia, Spain.

PMID: 29314394
DOI: 10.1002/chem.201705863

Abstract

This work has shown spin selectivity in electron transfer (ET) of diastereomers of (R,S)-naproxen-(S)-N-methylpyrrolidine and (R,S)-naproxen-(S)-tryptophan dyads. Photoinduced ET in these dyads is interesting because of the still unexplained phenomenon of stereoselectivity in the drug activity of enantiomers. The chemically induced dynamic nuclear polarization (CIDNP) enhancement coefficients of (R,S)-diastereomers are double those of the (S,S)-analogue. These facts are also interesting because spin effects are among the most sensitive, even to small changes in spin and molecular dynamics of paramagnetic particles. Therefore, CIDNP reflects the difference in magnetoresonance parameters (hyperfine interaction constants (HFIs), g-factor difference) and lifetimes of the paramagnetic forms of (R,S)- and (S,S)-diastereomers. The difference in HFI values for diastereomers has been confirmed by a comparison of CIDNP experimental enhancement coefficients with those calculated. Additionally, the dependence of the CIDNP enhancement coefficients on diastereomer concentration has been observed for the naproxen-N-methylpyrrolidine dyad. This has been explained by the participation of ET in homo-(R,S-R,S or S,S-S,S) and hetero-(R,S-S,S) dimers of dyads. In this case, the effectivity of ET, and consequently, CIDNP, is supposed to be different for (R,S)- and (S,S)-homodimers, heterodimers, and monomers. The possibility of dyad dimer formation has been demonstrated by using high-resolution X-ray and NMR spectroscopy techniques.

Keywords: chirality; diastereomers; electron transfer; hydrogen bonds; spin selectivity.