Molecular Mechanics Study of the Complexes of β-Cyclodextrin with 4-(dimethylamino)benzonitrile and Benzonitril

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Kluwer Academic Publishers
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Molecular Mechanics calculations with the Tripos Force Field were employed to study the complexation of 4-(dimethylamino)benzonitrile (DMABN) and/or benzonitrile (BN) with β-cyclodextrin (βCD). The systems studied have 1 : 1 (DMABN : βCD and BN : βCD), 2 : 2 (DMABN : βCD) and 1 : 1 : 2 (DMABN : BN : βCD) stoichiometries. Evidence for the formation of such complexes, binding constants and other thermodynamic parameters were extracted from the analysis of the steady state fluorescence measurements performed in a previous work. The Molecular Mechanics study, based on the energy changes upon guest-host approaching, was performed in vacuo and in the presence of water as a solvent. Results show that the driving forces for 1 : 1 complexation are mainly dominated by non-bonded van der Waals host : guest interactions. However, the driving forces for association between 1 : 1 complexes to give 2 : 2 homo- or 1 : 1 : 2 heterodimers are dominated by non-bonded electrostatic interactions. Head-to-head electrostatic interactions between βCDs, which are presumably due to the hydrogen bonding formation between secondary hydroxyl groups of CDs, are responsible for most of the stability of the dimers.
Cyclodextrins, Inclusion complexes, Dimers, Molecular mechanics calculations
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Journal of inclusion phenomena and molecular recognition in chemistry, 1999, 35 (3), pp.: 467-485.