Distinguishing Enantiomers by Tip-Enhanced Raman Scattering: Chemically Modified Silver Tip with an Asymmetric Atomic Arrangement
- 17 August 2020
- journal article
- research article
- Published by Wiley in Angewandte Chemie-International Edition
- Vol. 59 (34), 14564-14569
- https://doi.org/10.1002/anie.202005446
Abstract
Discrimination between enantiomers is achieved by tip-enhanced Raman scattering (TERS) using a silver tip that is chemically modified by an achiralpara-mercaptopyridine (pMPY) probe molecule. Differences in the relative intensities of thepMPY spectra were monitored for three pairs of enantiomers containing hydroxy (-OH) and/or amino (-NH2) groups. The N: or N+-H functionality of thepMPY-modified tip participates in hydrogen-bond interactions with a particular molecular orientation of each chiral isomer. The asymmetric arrangement of silver atoms at the apex of the tip induces an asymmetric electric field, which causes the tip to become a chiral center. Differences in the charge-transfer (CT) states of the metal-achiral probe system in conjunction with the asymmetric electric field produce different enhancements in the Raman signals of the two enantiomers. The near-field effect of the asymmetric electric field, which depends on the number of analyte functional groups capable of hydrogen-bond formation, improves the degree of discrimination.This publication has 49 references indexed in Scilit:
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