DS10 - Défi des autres savoirs

Photoinduced electron transfer in mechanically-interlocked molecules for super-resolution imaging and charge transport – PETIMIT

Submission summary

This interdisciplinary project aims to combine the unique properties of mechanically-interlocked molecules (ring-on-thread “rotaxane” structures) with fast photoinduced processes to produce new function on the molecular scale. Harnessing photoinduced electron transfer (PET), a primary process in photosynthesis, from a mobile electron donor ring component to a static fluorescent terminus will offer a means to quench fluorescence in dynamic interlocked molecular systems, which can be correlated with autonomous sub-molecular ring movement along the molecular axis under continual irradiation. This will allow us to i) induce “blinking” / modulation of molecular fluorescence coupled with ring movement as a new tool for super-resolution imaging, i.e. with a resolution higher than the light diffraction limit, following reconstruction of stochastic fluorescence bursts, and ii) utilize nanometric translational ring-movement movement as a means to shuttle electrons from one terminus to the other, thereby minimizing unwanted back electron transfer. Coupling mechanical movement with electron transfer is effectively exploited in certain enzymes to separate charge, but remains unprecedented in artificial molecules. Synthesis of the multicomponent supramolecular rotaxane architectures will be principally based on assembly of molecular building blocks developed in Bordeaux (including macrocyclic ring components, molecular recognition motifs, bulky stopper groups, electron donors, chromophores). In one design, the electroactive ring component can reside on 1 of 2 stations and comprises ultrahigh stability NIR-emitting chromophores. As well as rotaxanes where the electroactive ring will reside on 1 of 2 available stations, 0 station rotaxanes will assure free (and faster) ring movement compatible with cyclic electron transport. Studies of ring displacement and localisation within the [2]rotaxane will be based on dynamic NMR measurements for slower processes (ms to s) and photophysical measurements for faster (fs to ms) processes (time-resolved fluorescence and transient absorption spectroscopies), which will afford ring dynamics, electron transfer rates, transit times and relative residence times on each station. The later will correspond to fluorescence “off” and “on” times whose relative values can be tuned, a key consideration in ultra-high resolution optical microscopy, and the biased Brownian motion will be related to relative affinities on each of the 2 ring stations. Studies down to the single-molecule level will be undertaken on the “blinking” fluorescent systems in order to design a novel strategy ("Ring-STORM") to achieve localization microscopy on living cells without the need for overexpressing genetically encoded fluorescent proteins. This work will open the route for far-red multicolour super-resolution microscopy of endogenous molecules in live cells. The project regroups expertise in 3 different Bordeaux laboratories in the domains of organic and supramolecular chemistry, time-resolved spectroscopies, photophysics and imaging to the single molecule level, in order to develop nanoscopic electro-mechanic electron shuttles and imaging tools.

Project coordination

Nathan McClenaghan (Institut des Sciences Moléculaires)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

ISM - U-BORDEAUX Institut des Sciences Moléculaires
LP2N - IOGS Laboratoire Photonique Numérique et Nanosciences
LOMA - CNRS AQUITAINE Laboratoire Ondes et Matière d'Aquitaine - UMR CNRS 5798

Help of the ANR 532,278 euros
Beginning and duration of the scientific project: September 2016 - 48 Months

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