Electrochemical and Thermodynamic Studies of Inclusion Complex Formation between Tetradecyltrimethylammonium Bromide (TTAB) and β-Cyclodextrin (β-CD)

The behavior of the inclusion complex consisting of tetradecyltrimethylammonium bromide (TTAB) and β-cyclodextrin (β-CD) was studied using ion selective electrodes sensitive to surfactant ions. Two different methods were used in the construction of the ion selective electrode: (i) Membrane ion selective electrode (MISE) and (ii) Coating wire ion selective electrode (CWISE). The data obtained from two methods showed a consistency between two methods under all conditions. The CWISE method showed a faster response relative to the MISE ones. The experiments were carried out at different temperatures and in different concentrations of cyclodextrin. The data obtained indicate that the inclusion complexes S(CD) and S(CD)2 had formed between TTAB and β-cyclodextrin in an aqueous environment. In addition to the 1:1 complex, TTAB formed 1:2 complexes with β-cyclodextrin. Further investigation showed that K1 for S(CD) was greater than K2 for S(CD)2. Finally, thermodynamic parameters of the complexation, i.e., ΔH°, ΔG°, and ΔS° were also calculated.