Quantum chemical calculations on the weak polar host-guest interactions in crystalline cyclomaltoheptaose (beta-cyclodextrin)-but-2-yne-1,4-diol heptahydrate

摘要

X-ray diffraction analysis of the crystalline inclusion complex beta-cyclodextrin-but-2-yne-1,4-diol heptahydrate has shown that a number of C-H ... O and C-H....pi interactions occur between the cavity wall and the guest molecules. The interaction energies of these contacts are estimated by ab initio quantum chemical calculations. They are in the range 0.7 to 1.1 kcal mol(-1), which is far below values of conventional hydrogen bonding (4 to 6 kcal mol(-1) for O-H ... O hydrogen bonds in carbohydrates), but appreciably above energies of van der Waals contacts. (C) 1998 Elsevier Science Ltd. All rights reserved. [References: 11]