Conformers of guanosines and their vibrations in the electronic ground and excited states, as revealed by double-resonance spectroscopy and ab initio calculations

Strong intramolecular 5′-OH ⋯ 3-N hydrogen bonds stabilize guanosine, 2′-deoxyguanosine, and 3′-deoxyguanosine and fold them into a single preferred conformation (see picture), even in the absence of solvent interactions or DNA backbones. This conclusion was reached by means of a study combining UV-UV and IR-UV double-resonance laser spectroscopy and ab initio calculations.