Heptazine polymers have been recently recognized for their exceptional catalytic properties, (even water splitting), but examples of well-defined tunable monomeric heptazines are still scarce, because of severe synthetic limitations (before 2019, all syntheses relied on trichloroheptazine, obtained using PCl5 at high temperature). We want to take advantage of a recent discovery on heptazines synthesis (by the coordinator’s team, Partner 1), to develop a set of new photoactive heptazines, starting from new derivative with exchangeable pyrazoles, TDPH, prepared by mechanochemistry. From TDPH, the second to date heptazine described with exchangeable groups, we will generate a whole family of heptazines with adapted properties (especially adapted redox potentials by tuning the electron deficiency of the substituents) adequate for the collaborative tasks defined below. The project will gather the coordinator’s team and his partners in exploring the synthesis of new sets of heptazines and establishing their photophysical properties. This will be performed in close connections with DFT studies performed by our Partner 2 (TUM), in particular to estimate the redox potential of the excited state of several heptazines and to select most relevant heptazines for subsequent work. Heptazines are exceptional photooxidants (from the preliminary results in the coordinator’s team, likely the best organic photooxidants to date, comparable to iridium complexes). Their seminal catalytic potential to oxidize organic molecules was demonstrated in collaboration with our Partner 3 (ICSN). Here, we will explore more challenging photocatalyzed reactions. Heptazines should be able to oxidize unreactive positions (Csp3-H activation). As such, yet unsolved direct α-functionalization of simple primary,, or acyclic secondary aliphatic amines will be targeted. We will also tackle unprecedented organocatalyzed remote NH aliphatic amines functionalization and double α- and remote functionalization of aliphatic amines. With our Partner 4 (IRCER), we will also meanwhile, and afterwards, graft some of our active heptazines on hard recyclable materials like oxides, or possibly nanocarbons. This should lead to interesting complex 3D micro(nano)structures and architectures. Collaboration between Partner 4 and Partner 3 should also allow moving from homogeneous to heterogeneous catalysis, aiming at using solid supported heptazines in photocatalytic organic transformation to benefit from recyclability and easy purification.

The development of Circularly Polarized Organic Light Emitting Diodes (CP-OLED) based on chiral emitter has received renewed attention as a potential direction for increasing the energy efficiency and the contrast of conventional OLED displays. However, combining both high electroluminescence circular polarization and device performances has never been done so far and remains a considerable challenge for potential optoelectronic applications. Recently, the development of Thermally Activated Delayed Fluorescence (TADF) emitters has recently enhanced the efficiency of non-polarized OLED by converting both singlet and triplet excitons for light emission. In this context, the main objective of this multidisciplinary project is to design novel chiral TADF molecules (organic, organometallic) and incorporate them as emissive dopant in CP-OLED devices displaying high degrees of both electroluminescence polarization and efficiency.

The aim of the CHROMIC project is to develop new microfluidic circuits functionalized by mechanofluorochromic materials, i.e. materials whose fluorescence emission is sensitive to mechanical forces, then to use these new devices to measure the force exerted on a single microalgae passing through the circuit and finally to link the force applied in the microfluidic circuit to the increase in the extraction yield of the compounds produced by the microalgae. Our strategy for carrying out this multidisciplinary project is based on 4 stages. Firstly, mechanofluorochromic coatings will be prepared from polydiacetylene-fluorophore dyads, designed to combine versatile synthesis, high sensitivity to mechanical forces, high brightness and biocompatibility. Next, the response of these mechanofluorochromic coatings to friction forces will be calibrated using an AFM coupled to a fluorescence microscope: the tip of the AFM used in contact mode will apply a variable and controlled force, and the variation in the associated fluorescence emission will be recorded simultaneously. In the 3rd step, the microfluidic circuit will be optimised with a parallel architecture enabling a large number of microalgae to be analysed simultaneously, the size of the channels and restrictions will be adapted to study three species of microalgae of interest, and the associated image analysis protocol will be automated. Finally, three species of microalgae varying in size, rigidity and cell wall composition will be studied, and the mechanical force exerted by passage through the microfluidic restrictions, measured by mechanofluorochromism, will be correlated with the extraction yield of the compounds of interest. This project thus proposes a completely new approach to the measurement of forces at the scale of the single cell.

The project SOLPHOTOCAT is willing to investigate the development of new chemical devices for the storage and the release on demand of solar energy. The targeted system is a chemical system capable of (i) conversion of solar energy into a storable chemical energy via a photochemical transformation of A into B and (ii) release on demand the stored energy via the catalytic reverse transformation of B into A. The project is both targeting the development of new cheap and environmental-friendly chemical systems and the development of a microfluidic device capable of rapidly evaluating their performances in the whole system of storage and conversion of solar energy. SOLPHOTOCAT is a collaborative project between four complementary research teams that combine expertise from catalysis (LCC, Toulouse), photochemistry (PPSM, Paris Saclay), chemical engineering (LGC, Toulouse) and solar energy (PROMES, Perpignan).

The objective of the DECRET research program is twofold and aims to: • provide a novel solution, specific to and with improved sensitivity for the detection of radioactive elements: cesium and uranium, • ensure effective decontamination of all surfaces contaminated with these radioactive metals, in particular by applying to contaminated surfaces a foam composition containing magnetic nanoparticles functionalized with highly specific chelating agents and harvesting these nanoparticles by means of an industrial electromagnet. The aim of this research program is: 1) to build two quick detection systems for cesium and uranium. These systems will be based on microfluidic devices equipped with a specific detector for each of the two metals. These devices will be based on fluorescent calixarenes. 2) to develop new molecules capable of complexing these metals by exploring two possible technologies: • (a) sequestering agents with a pulvinic acid backbone (norbadione subunits, natural cesium sequestering agent found in certain mushrooms) and • (b) calixarenes (cyclic complexing agents). 3) to select the most effective cesium and uranium complexing molecules. 4) to graft them on support materials such as magnetic nanoparticles (doubly functionalized materials) or mesoporous materials (sponge and/or lightweight felt). 5) to incorporate these magnetic nanoparticles in the formulation of a foaming surface decontamination base, with high wetting power enhancing contact between nanoparticles and cesium or uranium contaminated sediments; compatibility of the various components with this aqueous foam will be controlled, thereby ensuring the grafted nanoparticles remain well dispersed and kept in suspension. The foam form will be easy to use in the field in case of accidental contamination. 6) to collect the radioactive elements by passing an electromagnet over the foam loaded with magnetic nanoparticles, 7) in parallel to being grafted on magnetic nanoparticles, the molecules developed under (2) will be grafted onto the surface of previously modified substrates, using a methacrylate monomer functionalized with a calixarene group or a pulvinic acid derivative. These structures would in particular allow to make filters or sponges capable of removing efficiently and selectively the cesium and uranium radioelements potentially present in an aqueous medium. At this stage, the tests will be performed on « cold » metals. Foam generation tests will be conducted on a pilot unit designed by CEA-DEN (Marcoule). Decontamination trials will be carried out on the one hand using the new chelating molecules and on the other hand using the complete and operational formulations derived from these molecules. The formulations will integrate suitable solvents, additives and supports to facilitate the extraction of metal from the contaminated substrate. In field applications, the two following systems will be combined: • a system comprising a metal-containing mesoporous material obtained by grafting polymer brushes functionalized with these new chelating agents. • and a foam generation system loaded with magnetic nanoparticles allowing quick decontamination by "magnetic harvesting". The former system is more suitable for the decontamination of effluents (by filtering) or of low porosity hard surfaces (by sponging) and the latter one for the operational decontamination of large surfaces (buildings, land).