Quantum Mechanical Study of the Inclusión Proceses of Adamantol Isomers by L-Tryptophan-Modified-Beta-Cyclodextrin

EDUARDO ALBERTO CASTRO; D.A.J. BARBIRIC; C.S. NASCIMENTO JR; W.B. DE ALMEIDA; H.F. DOS SANTOS

Mol Simul

Año: 2006 vol. 32 p. 623 - 631

            The complexation processes of 1 and 2-adamantanol with L-tryptophan-b-cyclodextrin have been studied using ab initio Hartree-Fock and Density Functional Theory levels. Structural and energetic analyses of the macrocyclic host, the guests and the corresponding inclusion complexes in different arrangements have been performed. For the host:guest inclusion processes, the up mode with the OH group of the alcohol oriented towards the secondary rim, is found to be in qualitative agreement with the experimental finding being the inclusion of the 2-Ada isomer more favorable by ~2 kcal/mol. A molecular recognition mechanism is proposed based on the host:guest relative dipole orientation. For the complex with the 2-Ada guest the dipoles are parallels favoring the interaction energy and for the 1-Ada complex they are antiparallels making the dipole-dipole potential repulsive. This mechanism can explain the small energy difference for the processes involving the adamantanol isomers.