The Nature of Hydrogen Bonds in Cytidine⋅⋅⋅H+⋅⋅⋅Cytidine DNA Base Pairs

Give and take: Combined NMR spectroscopic and quantum chemical investigations are used to characterize cationic hydrogen bonds found in C⋅C+ base pairs in DNA i-motif structures. The proton involved in the singly protonated base pair jumps between both cytidine nucleobases (see picture). The proton transfer can be described as asymmetric double-well potential with a proton hopping rate of at least 108 s−1.