Microsolvation of 2-Thiouracil: Molecular Structure and Spectroscopic Parameters of the Thiouracil-Water Complex

State-of-the-art :quantum-chemical Computations have been employed to accurately determine the equilibrium Structure and interaction,energy of the 2-thiouracil-water-complex, thus extending available reference data for biomolecule solvation patterns. The coupled-cluster level of theory in conjunction with a triple-zeta basis set has been considered together with extrapolation to the basis set limit, performed by employing second-order Moller-Plesset perturbation theory, and inclusion of core-correlation and diffuse-function corrections. On the basis of the comparison of experiment and theory for 2-thiouracil [Puzzarini,et al. Phys. Chem. Chem. Phys. 2013, 15, 16965-16975] structural changes due to water complexation have been pointed out. Molecular and spectroscopic properties of the 2-thiouracil water complex have then been studied by means of the composite computational approach introduced for the molecular structure evaluation. Among the results achieved; we mention the accurate determination of the molecular dipole moment and of the spectroscopic parameters required for predicting the rotational spectrum.