Ligand-Field Effects in a Ruthenium(II) Polypyridyl Complex Probed by Femtosecond X-ray Absorption Spectroscopy.
Yujin KimRory MaJunho LeeJessica HarichDaewoong NamSangsoo KimMinseok KimMiguel OchmannIntae EomNils HuseJae Hyuk LeeTae Kyu KimPublished in: The journal of physical chemistry letters (2021)
We employ femtosecond X-ray absorption spectroscopy of [Ru(m-bpy) 3 ] 2+ (m-bpy = 6-methyl-2,2'-bipyridine) to elucidate the time evolution of the spin and charge density upon metal-to-ligand charge-transfer (MLCT) excitation. The core-level transitions at the Ru L 3 -edge reveal a very short MLCT lifetime of 0.9 ps and relaxation to the lowest triplet metal-centered state ( 3 MC) which exhibits a lifetime of about 300 ps. Time-dependent density functional theory relates ligand methylation to a lower ligand field strength that stabilizes the 3 MC state. A quarter of the 3 MLCT population appears to be trapped which may be attributed to intramolecular vibrational relaxation or further electron transfer to the solvent. Our results demonstrate that small changes in the ligand field allow control of the photophysical properties. Moreover, this study underscores the high information content of femtosecond L-edge spectroscopy as a probe of valence charge density and spin-state in 4d transition metals.
Keyphrases
- density functional theory
- single molecule
- high resolution
- energy transfer
- molecular dynamics
- electron transfer
- living cells
- genome wide
- computed tomography
- dna methylation
- magnetic resonance imaging
- solid state
- drinking water
- health information
- risk assessment
- climate change
- dual energy
- magnetic resonance
- single cell
- health risk assessment
- heavy metals
- electron microscopy
- fluorescent probe