The laboratory’s research focuses on the structure, properties and reactivity of transition and post-transition metal complexes (lanthanides, actinides). The Laboratory also contributes to methodological developments driven by these applications.
Molecular magnetism
By means of wavefunction-based calculations, low-energy spectra can be determined and further analyzed. From demanding expansion of the wavefunctions (ab initio CASSCF type, and beyond), information ca be extracted to validate and rationalize experimental observations. Recently, the concept of spinmerism has emerged, as an extension of mesomerism to spin degree of freedom. Such picture somewhat expands the traditional spin-coupled (spin Hamiltonians) and spin-crossover views attributed to magnetic systems. Applications of inorganic compounds built on spin-crossover ion and radical ligand are being considered for spin-qubits generation.
Electronic transport
Electronic transport in molecules may not be described by molecular pictures. The main issues emerge from the non-equilibrium description of a molecular system contacted to semi-infinite electrodes. An alternative relies on a master equation using ab initio information extracted from the spin states wavefunctions. The multi-configurational electronic structure of the molecular junction has considerable impact on the characteristic i-V curve, and questions the relevance of orbital-based analysis.
Theoretical developments
Theoretical developments are constantly carried out to reach spectroscopy by means of orbital optimizations and the combination of perturbation theories. With a democratic description of ground and excited states goal in mind, the state specific construction of molecular orbitals might be desirable to reach spectroscopic accuracy and to deliver a compact form of the wavefunction.
In the mean time, strategies based on a partitioning of the Hamiltonian derived from the Rayleigh -Schrodinger (effective Hamiltonian theory) and Brillouin-Wigner expansion (RSBW and iterated RSBW) are pursued to reduce perturbations expansions and move away from size-consistency discrepancy.
Molecules and light
Owing to their strong absorption in the UV−visible region of the spectrum and long-lived excited states, transition metal complexes have become a central component for a variety of applications, such as photocatalysts, dye-sensitized solar cells (DSSCs), and organic light emitting diodes (OLEDs).
The rich electronic flexibility associated with their ability to bind various ligands and to link polymers, wires, proteins, and DNA opens the route to a number of functions, such as luminescent or conformational probes, diagnostic or therapeutic tools, photoswitches, and long-range electron transfer triggers.
The photophysics, photochemistry and (chiro)-optical properties of coordination compounds are investigated by means of various theoretical methods including density functional theory and multi-reference wavefunction approaches. Within the basis of spin−orbit and vibronically coupled Born-Oppenheimer electronic states, a realistic picture of the ultrafast (fs-ps) non-adiabatic dynamics is provided by solving the nuclear time-dependent Schrödinger equation. Quantum simulations in real time allow the interpretation and control of spin-vibronic mechanisms in coordination chemistry.
Images generated by Guillaume Rouaut with DALL.E (OpenIA image generator).