Thermodynamics of binding of neutral molecules to sulfobutyl ether beta-cyclodextrins (SBE-beta-CDs): the effect of total degree of substitution.
OBJECTIVE
To understand the role of degree of substitution on binding of molecules to beta-Cyclodextrins (beta-CDs) with varying degrees of sulfobutyl ether (SBE) substitution.


METHODS
Using UV spectroscopy, complexation constants of molecules to SBE-beta-CDs were estimated as a function of temperature, allowing for calculation of thermodynamic parameters, including the enthalpy and entropy of binding.


RESULTS
Binding constants of various molecules to SBE-beta-CDs did not show a uniform trend to total degree of SBE substitution. However, a distinct pattern was observed with the enthalpy and entropy of complexation. The results showed the complexation of substrates to SBE-beta-CDs to be more entropy-favored as the number of SBE groups increased. This favorable entropy of interaction was compensated by a less favorable enthalpy of interaction.


CONCLUSIONS
Enthalpy and entropy of complexation provided additional insight into the role that the alkylsulfonate groups may play in the complexation of molecules with SBE-beta-CDs.
Zia
V
V
Department of Pharmaceutical Chemistry, The University of Kansas, Lawrence 66047, USA.
Rajewski
R A
RA
Stella
V J
VJ
D003505:Cyclodextrins / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D013816:Thermodynamics; D047392:beta-Cyclodextrins
D003505:Cyclodextrins; D047392:beta-Cyclodextrins; C093196:SBE4-beta-cyclodextrin