Fluorescent molecules activate "green" chemical reactions

Scientists from the Green Organic Synthesis Team (GOST) research team led by Alvise Perosa and Maurizio Selva from Ca’ Foscari University of Venice have demonstrated for the first time the possibility of triggering chemical reactions by illuminating natural carbon nanoparticles, paving the way for new discoveries and applications in the field of green chemistry. The result was published in the prestigious scientific journal Green Chemistry, edited by the Royal Society of Chemistry.

The protagonists are carbon dots, carbon nanoparticles, known for properties such as luminescence and therefore studied in medicine in imaging diagnostics and as vectors for drugs. The Ca’ Foscari team managed to exploit luminescence to activate organic chemical reactions, using particles obtained from citric acid, a naturally abundant compound in citrus fruits, which is therefore a valid alternative to the rare, toxic, expensive and polluting metals used today by the industry.

“A molecule is photoluminescent when, excited under certain electromagnetic radiation, it then emits at a different wavelength, for example in the UV or visible field with colors ranging from blue, to yellow and red,” explains Alvise Perosa, Professor of Organic Chemistry at the Department of Molecular Sciences and Nanosystems. “We wondered if it was possible, by illuminating the carbon dots at the right frequency, to exploit the energy emitted to trigger reactions, i.e. to use those particles as photocatalysts. We have shown that this is possible and this is good news for the transition to green chemistry.”

“For the first time, the current generated by illuminating carbon dots was used for an organic reaction,” adds Emanuele Amadio, co-author of the study as research fellow at Ca’ Foscari. “We managed it after two years of work following the initial idea.”

Making this process greener now means obtaining the raw material (such as citric acid and glucose) directly from food waste and not from energy-intensive industrial synthesis.

“Research continues with the aim of promoting the circular economy,” explains Perosa, “which means producing carbon dots from natural and renewable raw materials, preferably waste.”

The research team is currently researching the possibility of extracting carbon dots from fish scales or from the shells of shellfish, among the main fish industry wastes. Carlotta Campalani , PhD student in Chemistry, is also engaged in this project, launched last year by Professor Selva in collaboration with his colleague Thomas Maschmeyer from Sydney University, and she explains, “Given the chemical composition of fish scales, rich in nitrogen, we are aiming to obtain highly luminescent carbon dots.”

Carbon dots are carbon nanoparticles known for their luminescence properties, non-toxic and biocompatible, stable and soluble in water, cheap to produce and their synthesis requires only raw material and water, therefore it does not require the use of solvents harmful to humans and the environment.