PhD in chemistry (M/F) – Photoactive organic radicals for photoswitching and sensing magnetic hyperthermia

The research work will address challenging issues regarding the synthesis of fluorescent and photochromic organic radicals to manufacture and trigger dual nanoassemblies, endowed with magnetic and optical activity, in the framework of on-command nanomedicine.

Context. Magnetic hyperthermia has appeared as a particularly attractive tool in nanomedicine for on-command drug delivery and activation of heat-triggered processes to fight against diseases. It involves magnetic nanoparticles that generate heat due to energy losses upon periodic alignment along an applied alternating magnetic field. Although numerous nano-objects have been manufactured up to now, the spatial diffusion and time kinetics of the released heat still remain unclear, which requires adapted probes. In this respect, photoactive p-conjugated organic units display the great advantages to sense or vary the nanoparticle’s magnetic moment by exploiting the sensitivity of their excited state to the electronic and thermal surroundings. We will thus investigate how light could impact the magnetic properties at short ns and sub-ns timescales and conversely how magnetic switching could influence the dynamics of photoexcited states, which would bring considerable progress in the design of performing materials. The carried studies could present perspectives in the field of spin-based information encoding.

Research studies. The multiple goal of the planned researches will be to design, elaborate and investigate hybrid nanoassemblies, composed of organic radicals, endowed with photoactive units (fluorescent, photochromic), and strong affinity toward superparamagnetic iron oxide nanoparticles. Particular attention will be paid to retention and reproducibility of the properties after self-assembly, which will require precise molecular engineering as well as size control of the nano-objects by resorting to microfluidic synthesis, allowing for additional post-processing like surface functionalization. This work will be carried out in the framework of interdisciplinary projects, funded by the French Research National Agency (ANR), addressing high-level challenges in light-matter interactions. It will involve strong collaborations with chemists at Sorbonne University (PHENIX), photophysicists at ENS Paris, physicists at Strasbourg University (IPCMS) and theoreticians at Perpignan University (PROMES), respectively experts in nanomagnetism and magnetic nanoparticles, ultrafast spectroscopic studies, ultrafast spin dynamics and theory of heat and optical coupling in magnetic nanoparticles and nanoassemblies.