Intermolecular hydrogen bonding in DNA base pairs interacting with different numbers of bare and hydrated Li+: NBO, QTAIM, and computational spectroscopic studies

•Interaction of different numbers of Li+ and hydrated Li+ with AT and GC.•Effect of Li+ on the structure of AT and GC, and hydrogen bonds strength in them.•QTAIM and NBO analysis for the change in the strength of hydrogen bonds in lithiated AT and GC.•IR and UV spectra of the AT and GC, and their lithiated forms.