Desmistifying the Strong Fluorescence of Bottom-up Carbon Dots

In this proposal we present a new successful approach to isolate and crystallize the organic fluorophores responsible by the claimed strong blue emission of carbon dots (CDs). These simple organic fluorophores are among the most efficient luminophores with a measured absolute quantum yield close to the unity, 97.1% (355 nm excitation) for a 2 ppm water solution. The compounds are obtained by optimization of the hydrothermal synthesis using citric acid and different ethylamines as precursors. Due to the small particle size and/or the presence of only light elements (C, N, O and H), our in-house diffractometers have not been effective in the elucidation of the new crystal architectures. We believe that the high-resolution data collected at the BM01 and ID22 beamlines will allow us to unveil the crystalline structures of these fluorophores.