The research activities of the PMM group are oriented toward the synthesis of molecular, supramolecular or polymeric pi-conjugated systems and coordination complexes featuring specific physico-chemical properties (absorption, luminescence, chiroptical properties, nonlinear optical properties, sensing...). Their main applications are in the field of opto-electronics. The originality of our approach consists in using the chemistry of organophosphorus/helicenes associated with organometallic/coordination (Ru, Pt, Re, Ir, Au etc) chemistry to prepare unprecedented molecules.
Conjugated P-heterocycles for opto-electronics
Keywords : P-heterocycles, pi-conjugated systems, fluorophores, optoelectronic devices
The research on P-containing π -conjugated has increased substantially thanks to the development of "plastic eclectronics". The P-atom can be involved in various bonding situations, which will strongly impacts the electronic delocalization. Furthermore, the specific reactivity of the σ3, λ3 P-atom affords an almost unlimited way of properties tuning. Embedding the P-center into an unsaturated ring is also an excellent way to modify the properties of the corresponding π -system. In this context, we developed variuos π -conjugated P-heterocycles phosphetenes (4 membered unsaturated P-ring), phospholes (5 membered P-ring), phosphinines (6 membered P-ring) or phosphenpines (7 membered P-ring). These compounds were successfully inserted into optoelectronic devices (OLED, OFETs etc).
Homo- and Heteroleptic complexes of ruthenium : multiphoton absorption, photosensitization and functional materials
Keywords : coordination complexes, pi-conjugated systems, two-photon photo-absorbers, advanced materials
We are interested in the study of RuLn(bpy)3-n heteroleptic complexes with a large effective cross-section (biphotonic absorption) and carrying a complementary function. We wish to extend their potential to fileds where the use of efficient multiphotonic absorbers is critical (photo-induced polymerization, phototherapy, sensing...) and by their integration in multifunctional materials.
This work focus in particular on the engineering of two-photon photo-initiator complexes for the design of nanostructured molecular materials will be pursued along two lines:
- for interface (solide/liquid or gaz) detection (coll. J-P Malval [IS2M, Mulhouse], F. Gauffre, [ISCR], R. Marsac [GeoSciences Rennes]).
- for the development of new polymeric devices for detection, based on electrochemiluminescence of ruthenium complexes (coll. J-P Malval [IS2M, Mulhouse], N. Sojic [ENSCPB Bordeaux]).
Chiral organic π-conjugated systems
Keywords : Chiral organic dyes, circularly polarized luminescence, exciton coupling chirality, optoelectronic devices.
In a complementary approach to the organometallic one (see axis 2), we investigate the development of innovative chiral organic molecular materials based on ℼ-extended helical architectures resulting from the combination of helicene units and achiral organic dyes (diketopyrrolopyrrole, naphthalimide). This molecular engineering notably allows us to obtain fundamental insights into the electronic and structural factors (nature of the optical transitions, chiral exciton coupling) that govern the CPL process, and tune the latter across the visible and the far-red region (600-800 nm) with intense glum values (up to 3 x 10-2) at the molecular level (Chem. Sci. 2018, 9, 735 ; Chem. Eur. J. 2018, 24, 14484, Chem. Sci. 2020, 11, 567 , Coll. J. Autschbach, M. Srebro-Hooper, B. Jamoussi, N. Vanthuyne). Our growing expertise on this specific chiroptical property, which was notably reinforced by the development of a home-made CPL instrument in close collabroation with JASCO© company (AIS Rennes Métropole, 2017), allows us to investigate a diversity of chiral molecular systems either in solution (Coll. M. Stepien, J. Am. Chem. Soc. 2019, 141, 7421) or in solid state (films, powder). Finally, applications of these chiral molecular materials in optoelectronic devices such as OLEDs or in photovoltaics give us interesting opportunities to explore the potential of chirality in molecular electronics (Coll. C. Cabanetos, P. Blanchard, Chem. Eur. J. 2017, 23, 6277).
Chiral organometallic systems
Keywords : organometallic helicenes, chiroptical switches, circularly polarized luminescence, optoelectronic devices, fundamental chirality
The molecular engineering consisting of using the chemistry of metallic ions combined with the chemistry of helicenes gives access to original helical pi-conjugated structures showing great potential as chiral molecular materials for opto-electronic applications (Chem. Rev. 2019, 119, 8846). Such strategy allows the development of helical ligands incorporating diverse complexing units (ligands of phenyl-pyridine, bipyridine, terpyridyne, heterocyclic carbene, alcynyl type) and the study of their stereocontrolled coordination together with their resulting physico-chemical properties. We have thus prepared i) helicene-alkynyl-iron complexes with chiroptical switching properties (reversible tuning of their circular dichroism, optical rotation or Raman Optical Activity) and modifications in the telecommunication domain (Coll. F. Paul, J. Casado, M. Vallet, Angew. Chem. Int. Ed. 2016, 55, 8062), ii) helicene-NHC-iridium complexes with long-lived and circularly polarized phosphorescence (see figure, Coll. J. A. G. Williams, L. Di Bari, Angew. Chem. Int. Ed. 2017, 56, 8236), or iii) helicenic bipyridine-type systems with chiroptical tuning mediated by zinc coordination (J. Org. Chem. 2019, 84, 5383). Furthermore, fundamental chirality-related aspects such as parity violation effects in chiral molecules are examined in model chiral organometallic complexes (Coll. B. Darquié, Chirality 2018, 30, 147). All these studies are performed in close collaboration with theoreticians (M. Srebro-Hooper, J. Autschbach), a specialist of chiral separations (N. Vanthuyne) (ANR MetalHel), and more specific partners (ANR HEL-NHC, coll. V. César, M. Mauduit).