Binding of Flavylium Ions to Sulfonatocalix[4]arene and Implication in the Photorelease of Biologically Relevant Guests in Water

J Org Chem. 2019 Sep 6;84(17):10852-10859. doi: 10.1021/acs.joc.9b01420. Epub 2019 Aug 14.

Abstract

The formation of host-guest complexes between seven flavylium cations and water-soluble p-sulfonatocalix[4]arene (SC4) was investigated by UV/vis absorption, fluorescence, and NMR spectroscopies. The results show the cationic guests form complexes with affinities in the submillimolar range. A representative chalcone/flavylium photoswitch was investigated in more detail regarding its pH- and light-triggered interconversion between the two forms. The dramatic affinity differentiation of the SC4 binding of the two switchable species (40 M-1 for the trans-chalcone versus 3.5 × 104 M-1 for the flavylium cation) enables the pH-gated photocontrol of the complexation process. These responsive properties were explored to demonstrate the competitive and selective release of biologically relevant guests from their supramolecular complexes with p-sulfonatocalix[4]arene (SC4), following the principle of AND logic. The guest release can be reverted by the thermally activated reaction of the flavylium ion back to the trans-chalcone.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Calixarenes / chemistry*
  • Flavonoids / chemistry*
  • Hydrogen-Ion Concentration
  • Photochemical Processes*
  • Stereoisomerism
  • Water / chemistry*

Substances

  • Flavonoids
  • Water
  • Calixarenes