Ultrafast isomerization reactions underpin many processes in (bio)chemical systems and molecular materials. Understanding the coupled evolution of atomic and molecular structure during isomerization is paramount for control and rational design in molecular science. Here we report transient X-ray absorption studies of the photo-induced linkage isomerization of a Ru-based photochromic molecule. X-ray spectra reveal the spin and valence charge of the Ru atom and provide experimental evidence that metal-centered excited states mediate isomerization. Complementary X-ray spectra of the functional ligand S atoms probe the nuclear structural rearrangements, highlighting the formation of two metal-centered states with different metal-ligand bonding. These results address an essential open question regarding the relative roles of transient charge-transfer and metal-centered states in mediating photoisomerization. Global temporal and spectral data analysis combined with time-dependent density functional theory reveals a complex mechanism for photoisomerization with atomic details of the transient molecular and electronic structure not accessible by other means.
Bibliographical noteFunding Information:
This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division. This research used resources of the Advanced Light Source, Lawrence Berkeley National Laboratory, which is a DOE Office of Science User Facility. T.K.K. acknowledges funding from the National Research Foundation (NRF) grants, funded by the Ministry of Science and ICT (No. 2016K2A9A1A01945137, 2016R1E1A1A01941978, 2014R1A4A1001690, and 2016K1A4A4A01922028). N.H. acknowledges funding from the Max Planck Society, the City of Hamburg, and the German Science Foundation (DFG) through the SFB 925 “Light induced dynamics and control of correlated quantum systems”. J.J.R. and K.G. acknowledge funding from the National Science Foundation (CHE 0947031, CHE 1112250, and CHE 1602240).
© 2018 The Author(s).
All Science Journal Classification (ASJC) codes
- Biochemistry, Genetics and Molecular Biology(all)
- Physics and Astronomy(all)