Calorimetric studies on the complexation of several ferrocene derivatives by α- and β-cyclodextrin. Effects of urea on the thermodynamic parameters

Luis A. Godínez, Sonal Patel, Cecil M. Criss, Angel E. Kaifer

Research output: Contribution to journalArticle

86 Scopus citations

Abstract

The complexation of several alkyldimethyl(ferrocenylmethyl)ammonium cations, where the alkyl group is -CH3 (1+), -(CH2)6CH3 (2+), or -(CH2)7COOH (3+), by the hosts α- and β-cyclodextrin (α- and β-CD) was investigated in aqueous media using calorimetric and 1H NMR spectroscopic measurements. The calorimetric results indicate that the complexation of all the ferrocene-containing guests is enthalpically driven. β-Cyclodextrin binds all the guests primarily by including the ferrocenyl groups into its cavity. By contrast, α-cyclodextrin binds guests 2+ and 3+ by threading the aliphatic chains of these guests through its cavity. The zwitterionic, deprotonated form (3) of the latter guest is bound by partial inclusion of the ferrocenyl group, a mechanism similar to that prevalent in the complexation of 1+. The complexation processes of 1+ by β-CD and 2+ by α-CD were also investigated in water-urea mixtures. Our calorimetric data reveal that large concentrations of urea cause a substantial decrease in the binding constant for the complexation process. The presence of urea considerably diminishes the enthalpic stabilization of both complexes.

Original languageEnglish (US)
Pages (from-to)17449-17455
Number of pages7
JournalJournal of physical chemistry
Volume99
Issue number48
DOIs
StatePublished - 1995

ASJC Scopus subject areas

  • Engineering(all)
  • Physical and Theoretical Chemistry

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