Photophysical investigation of two emissive nucleosides exhibiting gigantic stokes shifts

Abstract

We report spectroscopic characterization of two emissive 2′-deoxycytidine analogues: 5-(5-phenylfuran-2-yl)-2′-deoxycytidine and 5-(1-phenyl-1H-pyrazol-3-yl)-2′-deoxycytidine. Their fluorescent properties were examined using a combined experimental and theory/simulation approach, where the latter was based on Born–Oppenheimer molecular dynamics and time-dependent density functional theory. The analogues were found to exhibit unusually large Stokes shifts in polar media (>100 nm), moderate fluorescence quantum yields, and their emissions were found to be very sensitive to the local dielectric environment. These two analogues of 2′-deoxycytidine thus hold a promising potential as probes in chemical biology. In addition, the accuracy of the theoretical models for determining the optical properties is validated, which opens up for a convenient way of assessing the potential of future probes.