Theoretical study of inosine tetrad and octamer interacting with alkali metal ions

Inosine tetrad and octamer incorporating with alkali metal ions (K(+) and Na(+)) have been studied using both the B3LYP method and MPW1B95 method in this paper. The optimized structures, relative stabilities and corrected binding energies of the tetrads and octamers have been determined. The outcomes show that both for the tetrads and octamers, the stability sequences are Na(+) > K(+) in gas phase, while the stability of the two cation complexes turns to be similar when including hydration effects. The outcomes suggest that B3LYP method could not obtain reliable results for the base stacking system, especially for 14-Na-14 complex. (C) 2008 Elsevier B.V. All rights reserved.