The effect of cytosine methylation on its halogen-bonding properties
This study shows the influence of a 5-methyl substituent on the interaction between 1-methylcytosine, 1,5-dimethylcytosine, 1-methyluracil and 1-methylthymine and dichloride (Cl2) and fluorine chloride (ClF). The methyl derivatives were selected because of the important role played by a methyl group at position 5 of the pyrimidine ring on the biological properties of nucleobases. Besides binding energies obtained at the MP2/aug-cc-pVDZ level, a variety of theoretical methods were used to analyze the structures of the different minima obtained. A total of 116 complexes have been studied.