Emissive Nucleosides as Molecular Rotors

Synthesis and spectral characterization of environmentally responsive fluorescent deoxycytidine analogs

“…3, bottom panel), which indicates molecular rotor behavior. 26 In contrast, to the properties of 2a, the pyrenylethynyldeoxycytidine 2b showed no clear dependence on solvent viscosity (data not shown). This behavior can be understood in the following way.…”

“…For this compound, a strong dependence on solvent viscosity was found resembling that observed for known molecular rotors. 26 Although 1b did not show molecular rotor behavior, rigidification of pyrrolocytosine moiety (elimination of the rotatable C-C biaryl bond) to furnish the 5,6-benzo-fused analog 3a produced a large positive impact on the quantum yield in organic solvents (Φ ~1.0) and brightness (compared with parent 1b). Further characterization of the 5,6-benzo-fused pyrrolocytidine analog 3a showed that it is extraordinarily sensitive to the presence of water; combined with a high quantum yield and large Stokes shift, makes this a promising nucleoside probe.…”

“…26 With the exception of analog 3a, all analogs described in this study possess a potentially rotatable C-C biaryl (or alkyne-aryl) bond as part of the fluorophore. We have, therefore also decided to investigate the relationship between the emission intensity and viscosity of the solvents.…”

“…Values of 1317 cp (glycerol) and 0.583 cp (MeOH) have been used for the viscosity of the solvents. 26 Values of 1.25 kg/L (glycerol) and 0.79 kg/L (MeOH) have been used for the density of the solvents.…”

“…24 Overall, we report the synthesis and spectral characterization of five pyrrolocytidine deoxynucleosides and a C5-ethynyl derivative of deoxycytidine (2b) and of deoxyuridine (2a). In particular, we have examined the effects of solvent polarity 25 and solvent viscosity 26 on the fluorescence associated these analogs.…”