Quantum chemical MP2 results on some hydrates of cytosine: binding sites, energies and the first hydration shell.
A detailed quantum chemical investigation was undertaken to obtain the structure and energetics of cytosine hydrates Cyt·nH2O, with n = 1 to 7. The MP2(fc)/aug-cc-pVDZ level was used as the standard, with some DFT (B3LYP) and coupled cluster calculations, as well as calculations with the aug-cc-pVTZ basis set added for comparison. In a systematic search for microhydrated forms of cytosine, we have found that several structures have not yet been reported in the literature. The energies of different isomers, as well as binding energies are compared. When predicting the stability of a complex, we suggest using a scheme where the water molecules are extracted from a finite model of bulk water. Finally, based on energetic data, we suggest a rational definition of the first hydration shell; with this definition, it contains just six water molecules.
Institute of Chemistry, Eötvös University, P.O. Box 32, H-1518 Budapest, Hungary. fg@chem.elte.hu.
Géza
G
Fogarasi
Péter G
PG
Szalay
D001665:Binding Sites; D003596:Cytosine / Q000737:chemistry*; D011789:Quantum Theory; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
D014867:Water; D003596:Cytosine