We have investigated dimethyl disulfide as the basic moiety for understanding the photochemistry of disulfide bonds, which are central to a broad range of biochemical processes. Picosecond time-resolved X-ray absorption spectroscopy at the sulfur K-edge provides unique element-specific insight into the photochemistry of the disulfide bond initiated by 267 nm femtosecond pulses. We observe a broad but distinct transient induced absorption spectrum which recovers on at least two time scales in the nanosecond range. We employed RASSCF electronic structure calculations to simulate the sulfur-1s transitions of multiple possible chemical species, and identified the methylthiyl and methylperthiyl radicals as the primary reaction products. In addition, we identify disulfur and the CH2S thione as the secondary reaction products of the perthiyl radical that are most likely to explain the observed spectral and kinetic signatures of our experiment. Our study underscores the importance of elemental specificity and the potential of time-resolved X-ray spectroscopy to identify short-lived reaction products in complex reaction schemes that underlie the rich photochemistry of disulfide systems.
Bibliographical noteFunding Information:
This work was supported by the Director, Office of Science Office of Basic Energy Sciences, the Chemical Sciences, Geo-sciences and Biosciences Division under the Department of Energy, Contract No. DE-AC02-05CH11231 (A.C., K.H., J.L., and R.W.S.). This research has been supported by grants of the National Research Foundation of Korea (NRF) funded through the Ministry of Science and ICT (No. 2016R1E1A1A01941978, 2014R1A4A1001690, and 2016K1A4A4A01922028) to K.H., R.M., and T.K.K. M.O., I.v.A., K.A., and N.H. acknowledge funding from the Max Planck Society and the City of Hamburg. M.O. and N.H. gratefully acknowledge financial support by the German Science Foundation (DFG) through the SFB 925 Light induced dynamics and control of correlated quantum systems. This research used resources of the Advanced Light Source (LBNL), which is a DOE Office of Science User Facility. We thank Bruce Rude for his continuous support of the experimental hardware.
All Science Journal Classification (ASJC) codes
- Colloid and Surface Chemistry