Research interest:

Our group focuses on the synthesis and study of new ligands and their associated homo- and heteroleptic coordination complexes which possess magnetic and optical (linear and non-linear) properties.

Our work relies essentially on the optimisation of our compounds’ excited states, reached through traditional one-photon absorption or through two-photon absorption. We place emphasis both on fundamental research and on design to specifically target certain applications, such as:

• Theranostic: combination of the words therapy and diagnostic, this medical field concerns the coupled imaging and precisely targeted treatment of cancerous cells. The treatment is carried out by photodynamic therapy, a technique based on the quenching of the triplet excited state of a photosensitiser by a dioxygen molecule, leading to singlet oxygen acting as a cytotoxic agent.
• Optical power limiting: a non-linear optical property of materials which results in the limitation of the transmission of light when the intensity of the incident light is high (which could be used to protect eyes from strong laser lights, for instance). This phenomenon requires the material to possess appropriate two-photon absorption (2-PA) and excited state absorption (ESA) properties.

Molecular Approach:

The development of optically active molecular building blocks in our group is ultimately centred on the synthesis of ruthenium(II) complexes for which the absorption (linear and non-linear) and emission (lem et t) properties are fine-tuned by the rational design of the associated ligands, based on 1,10-phenantholine moieties.

• Our primary interest is in the two-photon absorption cross section, for which the structure and electronic properties of the ligand play a fundamental role. A molecular engineering study was conducted, allowing us to highlight some clear correlations between molecular structure and third-order non-linear absorption efficiency (2PA).

See Chimia 2015, 69, 666-669

• The optically generated triplet excited state (³MLCT) of those complexes is then utilised in PhotoDynamic Therapy (PDT) or two-photon induced PDT (2PA-PDT). The latter is of considerable interest as it offers better penetration in biological environments and extremely good spatial resolution. This project is funded by the French National Research Agency (ANR – Project PDTX, partner).

For more information, see Chem Commun. 2009, 4590-4592 and Dalton Trans., 2015, 44, 16127-16135.

• Following previous work from G. Gasser (ENSCP, Paris) on Ru(II) complexes and because of the efficiency of our systems as photosensitisers (PS), we recently demonstrated the antibacterial activity of one of our complexes, a desirable property in the context of the current issue of antibacterial resistance.

For more details, see Chem. Med. Chem., 2018, 13, 2229-2239.

• The absorption profile of our compounds’ excited states, reached by two-photon absorption, can provide useful optical power limiting properties.Project funded by the French National Research Agency (ANR – Project IsoGate)

For more information, see Phys. Chem. Chem. Phys. 2011, 13, 17304-17312.

Towards Functional Molecular Materials:

The functional molecular complexes presented above can be utilised in the fabrication of functional molecular materials when combined with nanoparticles, for example by non-covalent interactions, encapsulation or covalent bonds. Here are a few examples:

• Grafting on gold nanoparticles / In collaboration with S. Roux (University of Franche-Comté). Interesting new properties were found for ruthenium(II) complexes grafted on NPs such as absorption saturation for high energy wavelengths and preservation of 2PA efficiency in the red and near-IR wavelengths.

For further details, see Phys. Chem. Chem. Phys, 2014, 16, 14826-14833.

• Functionalisation of extremely small silica NPs by Gd(III) and Ru(II) / In collaboration with Pr. O. Tillement and Dr. F. Lux (on the thesis of Charles Truillet) from the University of Lyon 1. These NPs proved interesting as bi-functional platforms and, therefore, for their application in theranostics (Ru(II) as photosensitisers and Gd(III) complexes as MRI contrast agents).

For more details, refer to Dalton Trans., 2013, 42, 12410-12420.