Periodic Reporting for period 1 - AURORA (Applying photon Up-conversion in ROtaxanes for super-Resolution microscopy Analyses)
Periodo di rendicontazione: 2023-10-01 al 2025-09-30
AURORA investigates an unconventional strategy for the design of molecular machines by employing [2]rotaxane architectures as platforms for fully autonomous nanoscale assemblies. Within these systems, the ring components undergo spontaneous translational random motions, a mechanical behavior capable of modulating their optical response when coupled to the Triplet–Triplet Annihilation photon Up-Conversion (TTA-UC) mechanism. This photophysical process enables the conversion of low-energy incident photons into higher-energy emission and remains remarkably efficient under low-intensity irradiation from standard, commercially available LED sources.
A key point of the project is the intentional integration of nanoscale mechanical dynamics with tailored photophysical functionality. This coupling was anticipated to generate intermittent fluorescence bursts, an optical “blinking” behavior, that can be exploited to achieve imaging resolutions surpassing the classical diffraction limit. Building on this effect, the resulting interlocked assemblies were designed as functional probes for a variant of single-molecule localization microscopy, designated “T2-STORM,” which enables super-resolution imaging without reliance on specialized chemical buffers or strictly regulated experimental conditions.
The AURORA research program is structured around three objectives:
1. Embedding the TTA process directly within rotaxane frameworks to achieve efficient photon upconversion.
2. Modulating stochastic emission events to improve “blinking” effect.
3. Deploying TTA-UC-active rotaxanes as probes for the T2-STORM high-resolution microscopy method.
A key point of the project is the intentional integration of nanoscale mechanical dynamics with tailored photophysical functionality. This coupling was anticipated to generate intermittent fluorescence bursts, an optical “blinking” behavior, that can be exploited to achieve imaging resolutions surpassing the classical diffraction limit. Building on this effect, the resulting interlocked assemblies were designed as functional probes for a variant of single-molecule localization microscopy, designated “T2-STORM,” which enables super-resolution imaging without reliance on specialized chemical buffers or strictly regulated experimental conditions.
The AURORA research program is structured around three objectives:
1. Embedding the TTA process directly within rotaxane frameworks to achieve efficient photon upconversion.
2. Modulating stochastic emission events to improve “blinking” effect.
3. Deploying TTA-UC-active rotaxanes as probes for the T2-STORM high-resolution microscopy method.
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.
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.
AURORA project allowed to the development of autonomous photoactive molecular machines that generate photons of high-energy from incident light of lower energy through the TTA-UC phenomenon. This represent the first examples of TTA-UC process produced in rotaxanes as a consequence of their interlocked architecture.
Even if the main goal of AURORA has not been achieved yet, i.e. promoting “blinking” luminescence as a consequence of internal motion in rotaxane, these promising results open the way for optimisations to design new generations of luminescent rotaxanes as tool for super-resolution imaging microscopy. Notably, prototypes of TTA-UC producing [3]rotaxanes have been designed and synthetized to counter this issue and work on photophysical properties determination is still in-progress to obtain an autonomous, blinking and luminescent mechanically interlocked molecular machine for super-resolution imaging microscopy.
Even if the main goal of AURORA has not been achieved yet, i.e. promoting “blinking” luminescence as a consequence of internal motion in rotaxane, these promising results open the way for optimisations to design new generations of luminescent rotaxanes as tool for super-resolution imaging microscopy. Notably, prototypes of TTA-UC producing [3]rotaxanes have been designed and synthetized to counter this issue and work on photophysical properties determination is still in-progress to obtain an autonomous, blinking and luminescent mechanically interlocked molecular machine for super-resolution imaging microscopy.