Chiral Recognition of Chiral (Hetero)Cyclic Derivatives Probed by Tetraaza Macrocyclic Chiral Solvating Agents via 1H NMR Spectroscopy

In the field of chiral recognition, chiral cyclic organic compounds, especially heterocyclic organic compounds, have attracted little attention and have been rarely studied as chiral substrates by means of 1H NMR spectroscopy. In this paper, enantiomers of thiohydantoin derivatives, representing typical five-membered N,N-heterocycles, have been synthesized and utilized for assignment of absolute configuration and analysis of enantiomeric excess. All enantiomers have been successfully differentiated with the assistance of novel tetraaza macrocyclic chiral solvating agents (TAMCSAs) by 1H NMR spectroscopy. Surprisingly, unprecedented nonequivalent chemical shift values (up to 2.052 ppm) of the NH proton of substrates have been observed, a new milestone in the evaluation of enantiomers. To better understand the intermolecular interactions between host and guest, Job plots and theoretical calculations of (S)-G1 and (R)-G1 with TAMCSA 1a were investigated and revealed significant geometric differentiation between the diastereomers. In order to evaluate practical applications of the present systems in analyzing optical purity of chiral substrates, enantiomeric excesses of a typical substrate (G1) with different optical compositions in the presence of a representative TAMCSA (1a) can be accurately calculated based on the integration of the NH proton's signal peaks. Importantly, this work provides a significant breakthrough in exploring and developing the chiral recognition of chiral heterocyclic organic compounds by 1H NMR spectroscopy.

A simple protocol for determination of enantiopurity of amines using BINOL derivatives as chiral solvating agents via1H- and 19F-NMR spectroscopic analysis

A rapid and simple protocol for the determination of enantiopurity of primary and secondary amines was developed by using enantiopure BINOL and their derivatives as chiral solvating agents via1H- and 19F-NMR spectroscopic analysis.

Differentiation of enantiomeric anions by NMR spectroscopy with chiral bisurea receptors

Enantiomeric ¹H NMR signals of chiral anions are separated by forming 1 : 1 and 1 : 2 host–guest complexes with chiral bisurea.

Retracted Article: Spatially resolved mechanical properties of photo-responsive azobenzene-based supramolecular gels

The mechanical properties of azobenzene-based gelators were finely controlled by UV irradiation.

Langmuir–Blodgett films of perylene bisimide derivatives and fluorescent recognition of diamines

A fluorescent film was constructed with the well-known Langmuir–Blodgett technique, and it showed exceptional sensing performances for some diamine vapors.