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^FL and G^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 ^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^FO and nucleobases.