Marta Cervero and, F. Mendicuti
Jan 28, 2000
Citations
1
Influential Citations
44
Citations
Journal
Journal of Physical Chemistry B
Abstract
Steady-state fluorescence and molecular mechanics have been used to study the inclusion complexes of dimethyl 2,6-naphthalenedicarboxylate (DMN) with α- and β-cyclodextrins (CDs). Emission spectra of DMN show two bands whose ratio is very sensitive to the medium polarity. From the change of this ratio with CD concentration and temperature, the stoichiometry, the formation constants, and the changes of enthalpy and entropy upon inclusion of complexes formed were obtained. Stoichiometry depends on the host CD used. The estimated formation constants at 25 °C were (8.2 ± 0.6) × 105 M-2 for DMN:αCD2 and 1311 ± 57 M-1 for DMN:βCD. A dependence of the thermodynamic parameters ΔH° and ΔS° on the temperature was also found. Both complexes showed a negative ΔCp°. In addition, DMN seems to be a good probe for estimating microenvironmental polarity. Molecular mechanics calculations were also employed to study the formation of 1:1 and 1:2 complexes of DMN with both α- and βCDs. The study was mainly performed in the pr...