Issue 3, 2021

On Raman optical activity sign-switching between the ground and excited states leading to an unusual resonance ROA induced chirality

Abstract

Raman optical activity (ROA) spectra recorded for a chiral naphthalene diimide derivative (nBu-NDI–BINAM) dissolved in a series of solvents exhibit strong solute to solvent induced chirality with: (1) dominating bands of solvents, (2) nBu-NDI–BINAM resonance ROA (RROA) bands which are barely visible, (3) monosignate RROA Solvent spectra with an unexpected sign concordant with that of the ECD band of the resonant electronic state, (4) bisignate RROA bands for a few solvents, and (5) superposition of non-resonant and resonant ROA bands of the chiral solvents. The unusual ROA enhancement was explained in terms of resonance energy transfer with resonant Raman emission. The surprising RROA sign-switching was found to be due to specific conformational equilibria where one solute conformer dominates in the ground and the other in the first excited singlet state, and, the signs of the related ECD bands of these two conformers are opposite.

Graphical abstract: On Raman optical activity sign-switching between the ground and excited states leading to an unusual resonance ROA induced chirality

Supplementary files

Article information

Article type
Edge Article
Submitted
26 Sept. 2020
Accepted
29 Okt. 2020
First published
02 Nov. 2020
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2021,12, 911-916

On Raman optical activity sign-switching between the ground and excited states leading to an unusual resonance ROA induced chirality

E. Machalska, G. Zajac, M. Baranska, D. Kaczorek, R. Kawęcki, P. F. J. Lipiński, J. E. Rode and J. Cz. Dobrowolski, Chem. Sci., 2021, 12, 911 DOI: 10.1039/D0SC05345G

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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