Photoactive transition metal complexes - from fundamentals to applications

Photoactive transition metal complexes have attracted interest for many decades. Because of the presence of metal ions, d-orbitals can be involved in photophysical and photochemical processes and present fundamental interests, as these are different from what is occurring in purely organic photoactive compounds. Over the years, such research has resulted in the use of photoactive transition metal complexes in a wide range of technological applications such as solar cells, photocatalysis for organic synthesis, displays, lighting, sensing, bioimaging, anti-cancer therapies, etc.

The project has for main objective the study of the non-radiative states of such materials. Indeed, while the radiative state has gathered the most interest over the years, the overall photophysical properties of the complexes are very dependent on the non radiative processes. To achieve this, the initial stages of the project will focus on preparing and studying the early photophysical processes in homologous series of complexes build around archetypal complexes. Through collaborations, recently developed techniques for studying photophysical properties at the fs-scale will be used to revisit the known materials and obtained understanding of these ultrafast processes throughout the homologous series.
This new knowledge will then be used to study in details a particular class of emissive complexes recently developed in the group (unpublished) in which a large distortion of the excited state results in improved emissive properties. This is very unusual as a large deformation of the molecule in the excited state results in general in potential energy surfaces crossings and very efficient non radiative deactivation. The question is then: why a chemical design which should result, based on current knowledge, in very competitive non radiative processes leads in fact to very uncompetitive non radiative processes?

This fundamental research is expected to provide a new and more complete understanding of the photophysical processes in organometallic complexes and allows for the design of improved materials for a range of applications across the EPSRC remit such as materials for energy (efficiency, sustainability ,and replacement of scarce elements), organic synthesis (through photocatalysis), and medical applications (e.g. sensing and photodynamic therapy).