Synthesis and photophysical properties of 2′-deoxyguanosine derivatives labeled with fluorene and fluorenone units: toward excimer probes

In this study we prepared two fluorescent nucleosides, G super(FL) and G super(FO), comprising 2'-deoxyguanosine units covalently bound to 2-ethynylfluorene and 2-ethynyl-9-fluorenone moieties, respectively. The photophysical properties (fluorescence emission shifts and emission intensities) of these fluorescent nucleosides are solvent-dependent. Most notably, G super(FO), which bears a guanine nucleobase as its electron-donating group, displays an excimer emission in nonpolar solvents; accordingly, we used excimer emission titration to determine the binding constants for the interactions between G super(FO) and nucleobases.