Our group specializes in the elucidation of reaction mechanisms, and we are always open to offering these "mechanistic services" through collaborations. For those who seek to understand the mechanism of their reactions, we have several spectroscopic tools to determine the key steps.
Mechanistic Services
Spectroscopic tools
∆G°
Thermodynamics of electron transfer by electrochemistry
The viability of an electron transfer as often proposed in photoredox can be evaluated ex-situ by electrochemical method. The identification of redox potentials of photocatalysts and substrates by cyclic voltammetry is therefore used to propose the feasibility (or free energy, ΔG) of electron transfer.
Identification of intermediates by flash photolysis
The detection of a reaction intermediate during a chemical transformation is the most direct means of validating its mechanism. For photoactivated reactions, we use flash photolysis to identify the intermediates formed from their transient absorption spectra and their kinetics.
Validation of mechanisms by DFT
Our projects routinely use DFT to evaluate the free energy of proposed mechanisms and identify the most likely transition states. Theoretical NMR, (resonance) Raman, IR and UV-Vis (TD-DFT) spectra can also be produced and compared to spectra obtained experimentally.
Reaction kinetics between substrate and photocatalysts
The excited state of a photocatalyst can react with a substrate by several mechanisms, including electron transfer or energy transfer. Thanks to the phenomenon of competition between these mechanisms and relaxation by emission, the reaction kinetics can be determined from the Stern-Volmer equation.
Φ
Reaction Quantum Yield Measurement
For each photon absorbed, how many molecules are produced? A ratio greater than 1 necessarily indicates a chain reaction. Determining the quantum yield (Φ) is thus a direct means of proving a closed cycle, and is done using an actinometry protocol. [1]