Calorimetric and NMR studies on the direct correlation between supramolecular complex structure and the thermodynamics of N‐benzyloxycarbonyl‐L‐aspartic and ‐glutamic acid inclusion complexes with mono‐ and bis(trimethylammonio)‐β‐cyclodextrins

Abstract

AbstractThe stability constants and standard Gibbs energy, enthalpy and entropy changes for the 1:1 inclusion complexation of N‐benzyloxycarbonyl‐L‐aspartic and ‐glutamic acids with native β‐cyclodextrin (β‐CD), mono(6‐amino‐6‐deoxy)‐β‐CD, mono(6‐trimethylammonio‐6‐deoxy)‐β‐CD and A,B‐, A,C‐ and A,D‐bis(6‐trimethylammonio‐6‐deoxy)‐β‐CDs were determined in aqueous phosphate buffer (pH 6.9) at 298.15 K by titration microcalorimetry. The supramolecular complex structures were elucidated from 1D and 2D NMR spectra, including ROESY, COSY and HOHAHA techniques. Combining the results obtained from the microcalorimetric and NMR studies, we elucidated not only the detailed complex structures and the thermodynamic consequences, but also the mutual dependence between the complex structure and the overall complexation thermodynamics. Copyright © 2001 John Wiley & Sons, Ltd.