Harnessing Molecular Fluorophores in the Carbon Dots Matrix: The Case of Safranin O

Meloni, Manuela;Stagi, Luigi;Sanna, Davide;Garroni, Sebastiano;Calvillo, Laura;Terracina, Angela;Cannas, Marco;Messina, Fabrizio;Carbonaro, Carlo Maria;Innocenzi, Plinio;Malfatti, Luca

2022-01-01

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Abstract

The origin of fluorescence in carbon dots (C-dots) is still a puzzling phenomenon. The emission is, in most of the cases, due to molecular fluorophores formed in situ during the synthesis. The carbonization during C-dots processing does not allow, however, a fine control of the properties and makes finding the source of the fluorescence a challenging task. In this work, we present a strategy to embed a pre-formed fluorescent molecule, safranin O dye, into an amorphous carbonaceous dot obtained by citric acid carbonization. The dye is introduced in the melted solution of citric acid and after pyrolysis remains incorporated in a carbonaceous matrix to form red-emitting C-dots that are strongly resistant to photobleaching. Embedding dyes in amorphous C-dots represents an alternative method to optimize the emission in the whole visible spectrum.