A correlated ab initio quantum chemical study of the interaction of the Na⁺, Mg²⁺, Ca²⁺ and Zn²⁺ ions with the tautomers of cytosine in the presence of polar solvent

The interactions of the metal ions Na⁺, Mg²⁺, Ca ²⁺ and Zn²⁺ with cytosine have been investigated with inclusion of solvent effects. Computations have been performed at the density functional and Møller-Plesset levels of theory within the IEFPCM solvent model. It has been found that the inclusion of the solvent environment is essential for giving more biologically realistic results. Earlier gas-phase findings of the stabilisation of rare tautomeric forms by the metal ions have been reproduced, with the presence of the solvent further affecting the relative stabilities.