Thermodynamics of molecular recognition of bile salts by 3,6'-(oligoethylenediamino-bridged) beta-cyclodextrin dimers.
The molecular recognition behaviors of some representative bile salts by three 3,6'-bridged beta-cyclodextrin dimers with oligo(ethylenediamino) linkers in different lengths, i.e. 3,6'-(ethylenediamino-bridged) beta-cyclodextrin dimer (1), 3,6'-(diethylenetriamino-bridged) beta-cyclodextrin dimer (2), and 3,6'-(triethylenetetraamino-bridged) beta-cyclodextrin dimer (3), were investigated in aqueous phosphate buffer solution (pH 7.20) at 25 degrees C by means of 2D NMR spectroscopy and isothermal titration microcalorimetry. Owing to the cooperative host-linker-guest binding mode between host and guest, these 3,6'-bridged beta-cyclodextrin dimers showed significantly enhanced binding abilities and molecular selectivities as compared with native beta-cyclodextrin through the simultaneous contributions of hydrophobic, hydrogen bond, and electrostatic interactions. Thermodynamically, the inclusion complexations of these beta-cyclodextrin dimers with bile salts were mainly driven by large enthalpic gain, accompanied by slight to moderate entropic loss. An enthalpy-entropy compensation analysis demonstrated that these beta-cyclodextrin dimers experienced large conformational changes and extensive desolvation effect upon inclusion complexation with guest molecules.
Liu
Yu
Y
Department of Chemistry, State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, P.R. China. yuliu@nankai.edu.cn
Kang
Shu
S
Chen
Yong
Y
Cao
Rui
R
Shi
Jun
J
D001647:Bile Acids and Salts / Q000737:chemistry*; D002151:Calorimetry; D019281:Dimerization; D008024:Ligands; D008958:Models, Molecular; D015394:Molecular Structure; D013816:Thermodynamics; D017186:Titrimetry; D047392:beta-Cyclodextrins / Q000138:chemical synthesis* / Q000737:chemistry*
C524487:3,6'-(diethylenetriamino-bridged) beta-cyclodextrin dimer; C524486:3,6'-(ethylenediamino-bridged) beta-cyclodextrin dimer; C524488:3,6'-(triethylenetetraamino-bridged) beta-cyclodextrin dimer; D001647:Bile Acids and Salts; D008024:Ligands; D047392:beta-Cyclodextrins