Diquats with Robust Chirality: Facile Resolution, Synthesis of Chiral Dyes, and Application as Selectors in Chiral Analysis

• Published in: Chemistry : a European journal Vol. 24; no. 30; pp. 7601 - 7604
• Main Authors: Talele, Harish R., Koval, Dušan, Severa, Lukáš, Reyes‐Gutiérrez, Paul E., Císařová, Ivana, Sázelová, Petra, Šaman, David, Bednárová, Lucie, Kašička, Václav, Teplý, Filip
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 28.05.2018; Wiley Subscription Services, Inc
• Subjects: Atomic structure; capillary electrophoresis; Chemistry; Chemistry, Multidisciplinary; chiral selector; Chirality; Diquat; Dyes; helical chirality; Molecular chains; N-heterocyclic cations; Nitrogen atoms; Physical Sciences; Racemization; racemization barrier; Science & Technology; Selectors; Synthesis; chiral selector; HELQUATS; helical chirality; N-heterocyclic cations; QUATERNARY-SALTS; STEREOCHEMISTRY; racemization barrier; STATE; SPECTRA; DERIVATIVES; DICATIONS; capillary electrophoresis
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201800369

Diquats with extremely high racemization barriers with ΔG≠theor of 233 kJ mol−1 at 180 °C are described. Reported configurational robustness is due to a combination of two structural features: the rigid o‐xylylene tether connecting the nitrogen atoms and the presence of two substituents in the bay region of the bipyridinium scaffold. The straightforward synthesis of diquats, plus facile resolution and derivatization make them attractive for chiral application studies. This is demonstrated by: 1) synthesis of the first non‐racemic diquat dyes with pronounced chiroptical properties, and 2) capability of diquats to interact stereospecifically with chiral molecules. This suggests potential for diquat derivatives to be used as chiral selectors in separation methods. Choose your chirality: Facile access to enantiopure diquats with extreme configurational stability is described for the first time along with their derivatization and application as chiral selectors.