Theoretical study of the inclusion complexes of α and β-cyclodextrins with decyltrimethylammonium bromide (DTAB) and tetradecyltrimethylammonium bromide (TTAB)

The behavior of the inclusion complex formation of decyltrimethylammonium bromide (DTAB) and tetradecyltrimethylammonium bromide (TTAB) with α-cyclodextrin (α-CD) and β-cyclodextrin (β-CD) were studied in vacuum at the level of semi-empirical (AM1, PM3), HF/3-21G⁎ and B3LYP/3-21G⁎ theories. The inclusion complex formation of α-CD and β-CD DTAB and TTAB were studied just for the 1:1 complexes. The results indicate that the complexation of α-CD with DTAB is significantly more favorable than that of β-CD with DTAB. Interestingly, the trend of enthalpy changes of the complexation processes for α-CD and β-CD with TTAB is nearly the same. The negative enthalpy changes calculated from the statistical thermodynamic calculations at 1 atm and 298.15 K suggest that all of the inclusion complexations are favored enthalpy-driven processes.