AURORA is based on the development of mechanically interlocked molecular machines fuelled by light for efficient Triplet-Triplet Annihilation photon Up-Conversion (TTA-UC) in order to exploit the dynamic of rotaxane sub-components for the production of “blinking” luminescence. Three areas of chemistry have been interconnected to achieve this goal :
1. Conception and synthesis of rotaxanes:
Initially, Dr. Pairault’s skills in organic synthesis and mechanically interlocked molecules, coupled to Dr. McClenaghan’s expertise in photochemistry, have been crucial to design molecular machines bearing key elements to perform the TTA-UC. Dr. Pairault designed and synthesized a library of fluorescent macrocycles and others molecular components which include chromophores that are part of the TTA-UC process. From these elements, several fluorescent [2]- and [3]rotaxanes were synthetized to modulate macrocycle shuttling speed, steric hindrance or pair of associated chromophores to study their luminescence properties via TTA-UC process.
2. Spectroscopy analyses:
After successfully completing the synthesis of the fluorescent rotaxanes, Dr Pairault studied the stochastic motion of the macrocycle along the thread of the rotaxanes by Nuclear Magnetic Resonance (NMR) spectroscopy in order to extract macrocycle shuttling rate and thermodynamic properties of the rotaxanes. Additionally, Dr Pairault, in collaboration with Dr. Silswal and Dr. Oliveira-Decarli, measured the photochemical properties and received advanced training in the primary host at Molecular Science Institute (ISM, CNRS/Université de Bordeaux). Studies were performed using steady state and time-resolved transient-absorption and fluorescence spectroscopies to determine notably the absorption spectrum of rotaxanes, corresponding fluorescence intensity and lifetimes, as well as up-converted light generated via TTA-UC process.
3. Single-molecule microscopy studies:
After proving these interlocked systems have been capable to perform TTA-UC process during photochemistry experiments, best rotaxanes with promising TTA-UC behaviour have been tested in single-molecule super-resolution microscopy. During these experiments, no “blinking” effect was detected, however, new rotaxanes, based on platinum-containing chromophores, have been designed to improve potentially not detected “blinking” signals, keeping the way open for these systems to be employed for super-resolution imaging microscopy technique.
AURORA results have been disseminated through communications in international conferences and seminars. During the course of the MSCA-PF action, different public engagement activities have been performed. For this, Dr. Pairault participated in different outreach activities for disseminating his research work targeting a broad audience. These activities include the “Chimie de Comptoir 2024 » event in Talence and the "DECLICS 2023" event at Gustave Eiffel high school in Bordeaux, an event in charge of communicating with high school students about the chemist work. In these events, Dr. Pairault explained AURORA project ambitions and progress as well as the overall experience of participating in a MSCA-PF European action.
