DFT rationalization of the room-temperature luminescence properties of Ru(bpy) 3 2+ and Ru(tpy) 2 2+ : 3MLCT–3MC minimum energy path from NEB calculations and emission spectra from VRES calculations

Adrien Soupart (1) , Isabelle M. Dixon (1) , Fabienne Alary (1) , Jean-Louis Heully (1)

1 PTC - Photochimie théorique et computationnelle (LCPQ)

Extensive experimental data covering 40 years of research are available on Ru(bpy) 3 2+ and Ru(tpy) 2 2+ , which are the archetypes of inorganic photochemistry. The last decade has enabled computational chemists to tackle this topic through density functional theory and to shed some new light on our old friends. For the first time, this theoretical study maps the minimum energy path linking the 3 MLCT (metal-to-ligand charge transfer) and the 3 MC (metal centred) states with the nudged elastic band (NEB) method, also providing the calculation of the corresponding energy barrier. Remarkably, the obtained data are in very good agreement with the experimental activation energies reported from variable temperature luminescence measurements. Calculation of vibrationally resolved electronic spectra (VRES) is also in excellent agreement with the experimental emission maximum and bandshape of Ru(bpy) 3 2+. Additionally, the 3 MC-GS minimum energy crossing point (MECP) was optimized for each complex. The combination of these data rationalizes the room-temperature luminescence of the bpy complex and non-luminescence of the tpy complex.

Domaines: Chimie théorique et/ou physique

Adrien Soupart, Isabelle M. Dixon, Fabienne Alary, Jean-Louis Heully. DFT rationalization of the room-temperature luminescence properties of Ru(bpy) 3 2+ and Ru(tpy) 2 2+ : 3MLCT–3MC minimum energy path from NEB calculations and emission spectra from VRES calculations. Theoretical Chemistry Accounts: Theory, Computation, and Modeling, 2018, 137 (37), 11 p. ⟨10.1007/s00214-018-2216-1⟩. ⟨hal-01741478⟩