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

• Published in: Theoretical chemistry accounts Vol. 137; no. 3; pp. 1 - 11
• Main Authors: Soupart, Adrien, Dixon, Isabelle M., Alary, Fabienne, Heully, Jean-Louis
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer Nature B.V 01.03.2018; Springer Verlag
• Subjects: Charge transfer; Chemical Sciences; Chemists; Density functional theory; Electronic spectra; Emission spectra; Luminescence; Mathematical analysis; Optical properties; or physical chemistry; Photochemistry; Room temperature; Theoretical and
• ISSN: 1432-881X; 1432-2234
• DOI: 10.1007/s00214-018-2216-1

Extensive experimental data covering 40 years of research are available on Ru(bpy)32+ and Ru(tpy)22+, 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 3MLCT (metal-to-ligand charge transfer) and the 3MC (metal-centred) states with the nudged elastic band 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 is also in excellent agreement with the experimental emission maximum and bandshape of Ru(bpy)32+. Additionally, the 3MC–GS minimum energy crossing point 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.