Characterizing the geometric and electronic structures of individual photoexcited dye molecules in solution is an important step towards understanding the interfacial properties of photo-active electrodes. The broad family of "red sensitizers" based on osmium(II) polypyridyl compounds often undergoes small photo-induced structural changes which are challenging to characterize. In this work, X-ray transient absorption spectroscopy with picosecond temporal resolution is employed to determine the geometric and electronic structures of the photoexcited triplet state of [Os(terpy)2]2+ (terpy: 2,2':6',2″-terpyridine) solvated in methanol. From the EXAFS analysis, the structural changes can be characterized by a slight overall expansion of the first coordination shell [OsN6]. DFT calculations supports the XTA results. They also provide additional information about the nature of the molecular orbitals that contribute to the optical spectrum (with TD-DFT) and the near-edge region of the X-ray spectra.
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- X-ray transient absorption spectroscopy
- Osmium polypyridyl complex
Zhang, X., Pápai, M. I., Møller, K. B., Zhang, J., & Canton, S. E. (2016). Characterizing the Solvated Structure of Photoexcited [Os(terpy)2]2+ with X-ray Transient Absorption Spectroscopy and DFT Calculations. Molecules, 21(2). https://doi.org/10.3390/molecules21020235