Stacked and covalently bonded MoS₂-nucleobase complexes: A first-principles study

In this work we study stacked and covalently bonded complexes formed by MoS₂ monolayer fragments and nucleic acid bases. The structures, interaction energies, and vibrational spectra of the complexes are determined using the DFT/M06-2X and MP2 quantum-chemical methods. The interaction energies of the covalently bonded complexes obtained in the calculations are much higher than the interaction energies of the stacked complexes. Accounting for the effects due to aqueous environment results in a significant decrease of the interaction energies of both types of complexes, but all complexes still remain stable in water. The covalent bonding in the complexes results in significant changes of the vibrational spectra of the bases, in particular, in a very significant increase in their Raman activities.