Premium
A theoretical study of the selective entrapment of alkali and ammonium cations between guanine tetramers
Author(s) -
Gresh Nohad,
Pullman Bernard
Publication year - 2009
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560280707
Subject(s) - chemistry , tetramer , intermolecular force , alkali metal , guanine , interaction energy , crystallography , ammonium , molecule , computational chemistry , organic chemistry , nucleotide , biochemistry , gene , enzyme
The selective binding of alkali and ammonium cations to the internal cavity formed by two coaxially stacked guanine tetramers is studied by performing theoretical computations of the intermolecular interaction energies of the cations with the tetramers. The binding sites investigated correspond to the structure‐directing sites, the formation of which seems necessary to promote tetramer aggregation. Comparative energy balances for complexation, which take into account the dehydration enthalpies of the cations, are in the order: Rb + > K + < Cs + < Na+. A refinement of the computations shows that, in fact, Na + prefers a different complexation site situated in the plane and in the center of one of the tetramers, a configuration in which this cation may conserve a coordinated water molecule. Even in this arrangement its structure‐directing complexation energy is smaller than that for K + .