Excited State Intramolecular Proton Transfer of 1-Hydroxyanthraquinone
- Received Date: 2015-04-20
- Proton transfer, Conical intersection, Transient absorption spectroscopy, 1-Hydroxyanthraquinone
Abstract: The excited state intra-molecular proton transfer dynamics of 1-hydroxyanthraquinone in solution are investigated by femtosecond transient absorption spectroscopy and quantum chemistry calculations. Two characteristic bands of excited state absorption and stimu-lated emission are observed in transient absorption spectra with the excitation by the pump wavelength of 400 nm. From the delayed stimulated emission signal, the time scale of the intra-molecular proton transfer is determined to be about 32 fs. The quantum chemistry calculations show that the molecular orbits and the order of the S2 and S1 states are rever-sal and a conical intersection is demonstrated to exist along the proton transfer coordinate. After proton transfer, the second excited state of tautomer populated via the conical intersection undergoes the internal conversion with ～200 fs and the following intermolecular energy relaxation with ～16 ps. The longer component 300 ps can be explained in terms of the relaxation from excited-state tautomer to its ground state. From our observations, two proton transfer pathways via a conical intersection are proposed and the dominated one preserves the molecular orbits.
|Citation:||Si-mei Sun, Song Zhang, Kai Liu, Ya-ping Wang, Miao-miao Zhou, Bing Zhang. Excited State Intramolecular Proton Transfer of 1-Hydroxyanthraquinone[J]. Chinese Journal of Chemical Physics , 2015, 28(5): 545-551. doi: 10.1063/1674-0068/28/cjcp1504078|