Anion Modulated Expression of Chirality in Hydrogen Bond Templated Mechanically Chiral [2]Rotaxanes

• Published in: Chemistry : a European journal Vol. 29; no. 21; pp. e202203502 - n/a
• Main Authors: Spicer, Rebecca L., Shearman, Curtis C., Evans, Nicholas H.
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 13.04.2023; Wiley Subscription Services, Inc
• Subjects: anion recognition; Anions; Cations; Chemistry; Chemistry, Multidisciplinary; Chirality; Hydrogen bonds; molecular shuttle; NMR; Nuclear magnetic resonance; Physical Sciences; Rotaxanes; Science & Technology; supramolecular chemistry; Urea; SQUARAMIDE; chirality; RECOGNITION; anion recognition; INTERLOCKED MOLECULES; SHUTTLE; SWITCHES; molecular shuttle; SQUARAINE ROTAXANE; CATENANES; rotaxanes; RING; supramolecular chemistry
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.202203502

The syntheses of two novel mechanically chiral rotaxanes containing urea and squaramide motifs (in yields of 33 % and 22 %, respectively) are presented. 1H NMR spectroscopic titrations reveal shuttling of the macrocycle – detectable by modulation of the expression of mechanical chirality in the NMR spectrum – is possible through the addition of achiral chloride anions, a process which is reversed by the addition of sodium cations. Anion recognition promotes the shuttling of the macrocyclic ring in mechanically chiral [2]rotaxanes. The position of the macrocycle is reported by changes in the diastereotopic behaviour in the 1H NMR spectrum. The macrocycle can be returned to its initial station upon removal of the anion.