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 language | English (US) |
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Pages (from-to) | 17449-17455 |
Number of pages | 7 |
Journal | Journal of physical chemistry |
Volume | 99 |
Issue number | 48 |
DOIs | |
State | Published - 1995 |
ASJC Scopus subject areas
- Engineering(all)
- Physical and Theoretical Chemistry