Density-Functional-Theory Study of α-Cyclodextrin Inclusion Complexes

We apply the density functional theory on the description of the alpha-cyclodextrin (alpha-CD) and the analysis of the molecular electrostatic potential (MEP) for complexes of this system with Na+, F-, CO32-, and N,N-dimethyl formamide, as substrates. Four exchange-correlation functionals were considered: one of the local density approximation, two of the generalized gradient approximation (BLYP and PBE), and one of the hybrid family. These exchange-correlation functionals were coupled with the DZVP/A1, DZVP, and TZVP basis set functions. All complexes were fully optimized by all methods. The experimental molecular structure of the alpha-CD compares better with that described by the PBE exchange-correlation functional. The MEP analysis shows that the electrostatic is quite relevant on the intermolecular interaction for the alpha-CD complexes in gas phase. Some of our results are in disagreement with those published previously with the PM3 semiempirical method and the B3LYP//PM3 method. (C) 2012 Wiley Periodicals, Inc.