A theoretical study of the selective entrapment of alkali and ammonium cations between guanine tetramers

Autor:	Nohad Gresh, Bernard Pullman
Rok vydání:	2009
Předmět:	Internal cavity Guanine Inorganic chemistry Condensed Matter Physics Alkali metal Atomic and Molecular Physics and Optics chemistry.chemical_compound Crystallography chemistry Tetramer Intermolecular interaction Molecule Ammonium Physical and Theoretical Chemistry Binding site
Zdroj:	International Journal of Quantum Chemistry. 28:49-56
ISSN:	1097-461X 0020-7608
DOI:	10.1002/qua.560280707
Popis:	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+.
Databáze:	OpenAIRE
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