Light-induced formation of silver(I)-mediated base pairs in DNA: Possibilities and limitations

Abstract

The applicability of the caged nucleoside CNPP (2′-deoxycytidine bearing an ortho-nitrophenylpropyl group at the exocyclic N4 position) in the light-triggered formation of three silver(I)-mediated base pairs was probed, namely C–Ag(I)–C, Im–Ag(I)–C and P–Ag(I)–C (Im = imidazole 2′-deoxyribonucleoside; P = nucleoside analogue with a 1H-imidazo[4,5-f][1,10]phenanthroline nucleobase surrogate). Generally, an increase in the duplex melting temperature was observed upon photo-deprotection in the presence of Ag(I), indicating the formation of the respective silver(I)-mediated base pair. Nevertheless, a complete photo-deprotection could not be achieved even under optimized conditions. A comparison of the results obtained for the three base pairs allows to derive some general conclusions regarding the optimal design of a metal-mediated base pair whose formation can be triggered by light.