Issue 35, 2022

Importance of molecular symmetry for enantiomeric excess recognition by NMR

Abstract

Recently prochiral solvating agents (pro-CSA) came under the spotlight for the detection of enantiopurity by NMR. Chemical shift non-equivalency in achiral hosts introduced by the presence of chiral guests yields observable resonance signal splitting (Δδ) correlating to the enantiomeric excess (e.e.). In this work, symmetry is our lens to explain porphyrin-based supramolecular receptor activity in a chiral environment. Based on extensive NMR analyses of the atropisomeric receptors, the host symmetry is shown to be affected by porphyrin nonplanarity and further desymmetrized in the presence of a chiral guest. As such, the exposed porphyrin inner core (N–H), with its strong hydrogen bond abilities, for the first time, has been exploited in enantiomeric composition analysis. Our approach in e.e. detection by N–H signals appearing in a previously underutilized region of the spectrum (below 0 ppm) shows chemical shift splitting (Δδ) three times more sensitive to enantiomeric compositions than previously reported systems.

Graphical abstract: Importance of molecular symmetry for enantiomeric excess recognition by NMR

Supplementary files

Article information

Article type
Communication
Submitted
05 Mar 2022
Accepted
30 Mar 2022
First published
30 Mar 2022
This article is Open Access
Creative Commons BY license

Chem. Commun., 2022,58, 5423-5426

Importance of molecular symmetry for enantiomeric excess recognition by NMR

K. Norvaiša, J. E. O’Brien, I. Osadchuk, B. Twamley, V. Borovkov and M. O. Senge, Chem. Commun., 2022, 58, 5423 DOI: 10.1039/D2CC01319C

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