Interactions of cytidine with N2-functionalized guanosines and cytidine – cytidine exchange involving a GC pair — NMR and fluorescence spectroscopic study

Two N2-functionalized guanosines by diphenylaminobiphenyl and di(2-pyridyl)aminobiphenyl have been found to act as the effective probes for G–C interactions in organic media. Because of the highly emissive nature of the N2-functionalized guanosines in the visible region, the GC base pair formation event accompanied by distinct fluorescence quenching can be readily monitored by fluorescence spectroscopy. NMR and fluorescence results confirm that the N2-arylguanosines form H-bonded pairs with cytidine, selectively. An unusual exchange pathway between non-bound cytidine and bound cytidine, in the GC pair, has been identified and extensively studied by NMR methods.