Cyclodextrinic carcerands. I. Would they form inclusion complexes? Computational study on structure and energetics

A structural and energetic study on three types of cyclodextrinic carcerands formed by linking two units of alpha-, beta-, gamma-cyclodextrin through methylene chains of several lengths was performed by molecular mechanics, and molecular dynamics simulations. The smaller carcerands are rigid and spherical, while the larger carcerands are more flexible, their cavities are more hidden, and they are spheroidal. The small carcerands having one bridge per glucose present "laevo", symmetrical, and "dextro" arrangements due to the formation of hydrogen bonds between the two CD units, while those with two bridges per glucose present only two conformations (symmetric and asymmetric). All the geometrical characteristics become more diffuse when the size of the cavity increases.