Asymmetric Azamacrocycles as Chiral Solvating Agents

Tanaka, Kōichi

doi:10.1002/9781119113874.ch12

Cited by 3 publications

(2 citation statements)

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“…On comparison of the 1 H NMR spectra of ( R )-DACH, ( S )-DACH, and their racemic mixture ( rac -DACH) in the presence of ( S )- H1 , it is interesting to note that a high degree of enantiomeric discrimination is achieved for some of the proton signals (Figure and Figure S15 in the Supporting Information). The chemical shift nonequivalence values reach up to 0.57, 0.36, and 0.35 (ΔΔδ, ppm) for H 3 , NH, and H 1 , respectively (Table ), which are among the highest for the reported CSRs so far . The remarkable signal separations are believed to be due to the strong ASE of the chiral bisporphyrin cavity associated with the allosteric effects induced by the formation of diastereoisomers.…”

Section: Results and Discussionmentioning

confidence: 93%

“…The chemical shift nonequivalence values reach up to 0.57, 0.36, and 0.35 (ΔΔδ, ppm) for H 3 , NH, and H 1 , respectively (Table 2), which are among the highest for the reported CSRs so far. 45 The remarkable signal separations are believed to be due to the strong ASE of the chiral bisporphyrin cavity associated with the allosteric effects induced by the formation of diastereoisomers. The signals of H 5 can also be separated with a ΔΔδ value of 0.14 ppm, in spite of the long distances to the amine groups and the porphyrin centers.…”

Section: Inorganic Chemistrymentioning

confidence: 99%

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Chiral Discrimination of Diamines by a Binaphthalene-Bridged Porphyrin Dimer

Yang

et al. 2017

Inorg. Chem.

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A pair of 1,1'-binaphthalene-bridged bisporphyrins, (R)- and (S)-H1, were designed to examine their chiral discrimination abilities toward a range of model diamines by using UV-vis absorption, CD, and H NMR spectroscopy with the assistance of DFT molecular modeling. The spectroscopic titrations revealed that (R)-/(S)-H1 could encapsulate (R)-/(S)-DACH and (R)-/(S)-PPDA in the chiral bisporphyrin cavities, leading to the selective formation of sandwich-type 1:1 complexes via dual Zn-N coordination interactions. In particular, the chiral recognition energy (ΔΔG°) toward (R)-/(S)-DACH was evaluated to be -4.02 kJ mol. The binding processes afforded sensitive CD spectral changes in response to the stereostructure of chiral diamines. Remarkable enantiodiscrimination effects were also detected in the NMR titrations of (R)-/(S)-H1, in which the nonequivalent chemical shift (ΔΔδ) can reach up to 0.57 ppm for (R)-/(S)-DACH. However, due to the large steric effect, another chiral diamine ((R)-/(S)-DPEA) could not be sandwiched in the chiral bisporphyrin cavity; therefore, (R)-/(S)-DPEA could hardly be discriminated by (R)-/(S)-H1. The present results demonstrate a chiral bisporphyrin host with integrated CD and NMR chiral sensing functions and also highlight the binding-mode-dependent character of its enantiodiscrimination performance for different chiral guests.

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Section: Results and Discussionmentioning

confidence: 93%

Section: Inorganic Chemistrymentioning

confidence: 99%