Hydrogen bonding between adenine and 2,4-difluorotoluene is definitely not present, as shown by concentration-dependent NMR studies

Abstract

The chloroform-soluble nucleobase derivatives N⁹-cyclohexylmethyladenine (A) and N¹-cyclohexylmethylthymine (T) have been synthesized in order to study hydrogen-bonding interactions between A and the thymidine mimic 2,4-difluorotoluene (F) in CDCl₃ at high concentrations. Concentration-dependent ¹H NMR experiments show that in the presence of F, A undergoes self-association rather than pairing with F. These results strongly support the assumptions made by Kool with regard to the lack of hydrogen bonding between adenine and 2,4-difluorotoluene.