Institut de Chimie Moléculaire et des Matériaux d'Orsay

Photochromism and photoswitchable systems

Pei Yu (Researcher), Anne Leaustic (Associate Prof.)

PhD students : Nicolo Baggi, Sophie Gadan

We are mainly interested in the design of novel molecular or hybrid systems displaying photo-responsive behaviors. A photochromic di(heteroaryl)ethene is generally used as the molecular switch as it can be toggled reversibly between two thermally stable states with different geometries and electronic structures.

A wide range of properties and functions can be photo-modulated by such a reversible structure switching. These photo-responsive systems may find potential applications in various fields like optoelectronics, catalysis, imaging and biology etc. Given the multidisciplinary nature of the topic, we often work in collaboration with experts in photo-physics and photochemistry (ENS Paris-Saclay), in electrochemistry (LEM) and theory (ITODYS).

Metal complexes with photo-switchable stability

Use of photochromic ligands in coordination chemistry may offer a simple and convenient way to regulate, in situ and without any waste, different properties of a given metal complex. We have designed a terthiazole-based photochromic ligand and synthesized a dimeric zinc complex, whose solution stability was found to strongly depend on the state of the photochromic ligand. Indeed, the difference in stability is so huge that an interesting light triggered release and uptake of zinc ions was observed. Moreover, a concomitant fluorescence switching allowed a simple monitoring of the process.

One appealing target would be to use such photochromic ligands to photo-regulate the concentration of some metal ions of biological interest in physiological medium .

Dual photo- and electro-switches

Offering one additional means of control electro-switchable photochromes are of particular interest and sought. A series of dicationic terthiazoles have been synthesized and characterized. Ongoing investigations suggest the possibility to achieve such dual photo- and electro-switching in both directions, in particular with one member of this family as schematized below.

More investigations along with theoretical calculations are needed to further confirm the bidirectional and electrochemical switching and understand the exact mechanism.

Collaborative projects (ANR and Labex)

We are also working in the framework of two ANR proposals (2018-2022).

• SWIST (SWItchable fluorescence hySTeresis by light), in collaboration with ENS Paris-Saclay (Dr. R. Métivier et al, coordinator) and ITODYS Paris-Diderot (Pr. F. Maurel). The project aims to develop novel nano-materials exhibiting photo-switchable hysteresis in fluorescence. The design of suitably functionalized photochromes with adequate optical properties is crucial for the success of the project.
• SpinFun (Spintronics with Functional Molecules) in collaboration with UMPhy-CNRS/Thalès (Dr. R. Mattana et al, coordinator), l’IEMN (Dr. D. Vuillaume et al) and CMN-University of Mons (Dr. G. Cornil et al). The target di(heteroaryl)ethenes should be able not only to form SAMs between two ferromagnetic electrodes but also to keep their photochemical reactivity in order to reversibly photo-switch the conductance and the magneto-resistance as well. 

In collaboration with ILV-UVQS Paris-Saclay, ENS Paris-Saclay and LPCIM-Polytechnique, we initiated a Labex Charmmmat project (2016-2018) aiming at the development of fluorescent MOFs (Metal- Organic Framework) for sensing and LEDs. Using a ligand displaying ESIPT-based (Excited State Intramolecular Proton Transfer) fluorescence, we have synthesized and characterized first porous and strongly fluorescent MIL-140c type MOFs. We are currently investigating use of such strongly fluorescent MOFs for sensing.

Last update on Feb. 28^th 2022