3-Substituted xanthines as promising candidates for quadruplex formation: computational, synthetic and analytical studies

Our computational studies suggest that 3-substituted xanthines are good candidates for tetrad and quadruplex structures. 3-Methylxanthine (3MX) has been synthesized from 7-benzylxanthine, and the existence of tetrameric and octameric aggregates of 3MX with NH4+, Na+ and K+ ions in the gas phase (MS) and in DMSO-d(6) solution (NMR) has been observed. The internal H-bonds (N1H center dot center dot center dot O6) are stronger than the external ones (N7H center dot center dot center dot O2) in these clusters (NMR).