Multiple inclusion complex formation of protonated ellipticine with cucurbit[8]uril: thermodynamics and fluorescence properties

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Abstract

The encapsulation of protonated ellipticine (EH+) in the cavity of cucurbit[8]uril (CB8) was studied in water at pH 4 with spectrophotometric, fluorescence spectroscopic and isothermal calorimetric measurements. The formation of three types of inclusion complexes was observed depending on the host and guest concentrations. Not only one, but also two EH+ was capable of encapsulation in CB8 in 37 μM EH+ solution and the thermodynamics of the binding steps were revealed. The produced very stable complexes showed markedly different absorption and fluorescence properties. When large excess of CB8 was employed in dilute (0.49 μM) EH+ solution, sequential binding of two CB8 occurred to the monomer alkaloid bringing about a substantial alteration in the fluorescence decay kinetics. The driving force of the 1:2 guest:host complex formation was much lower than that of 1:1 encapsulation.

Original languageEnglish
Pages (from-to)842-848
Number of pages7
JournalSupramolecular Chemistry
Volume28
Issue number9-10
DOIs
Publication statusPublished - Oct 2 2016

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Keywords

  • Alkaloids
  • binding affinity
  • calorimetry
  • fluorescence decay
  • host–guest complex

ASJC Scopus subject areas

  • Chemistry(all)

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