ISSN:
0894-3230
Keywords:
Organic Chemistry
;
Physical Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Analysis of temperature dependent equilibrium constant data for the complexation of α-cyclodextrin with approximately 70 different substrates demonstrates the existence of a general compensation effect. Enthalpies (kJ mol-1) and entropies (J K-1 mol-1) of complexation are related by ΔH = -5·70(±0·05) + [421·1(±1·2)]ΔS. A few substrates deviate from the general effect, possibly owing to reorganization of internal hydrogen bonding interactions. Complexation reactions involving β-cyclodextrin are found to divide into two groups. Eleven small molecule or ion substrates undergo isoentropic complexations with ΔS = -5·7±2 J K-1 mol-1. Fourteen larger substrate species exhibit a compensation effect with ΔH = -23·5(±0·2) + [634(±26)]ΔS. The compensation behavior of the two cyclodextrins is discussed in terms of bonding mechanisms and cavity size.
Additional Material:
3 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/poc.610081209
