title: Unravelling the early photochemical behavior of (8-substituted-7-hydroxyquinolinyl)methyl acetates through electronic structure theory and ultrafast transient absorption spectroscopy.
abstract: The photophysical processes and photochemical reactions in the ultrafast time region of (8-bromo-7-hydroxyquinolin-2-yl)methyl acetate (BHQ-OAc) in acetonitrile and neutral aqueous solutions were investigated using quantum chemical calculations and femtosecond transient absorption spectroscopy. After initial excitation into the π,π* excited state, BHQ-OAc undergoes an ultrafast intersystem crossing (ISC) into a π,π* excited triplet state on a timescale of 16 ps. The n,π* and π,π* excited singlet and triplet states involved in the photochemistry were identified by means of their characteristic excited state absorption (ESA) bands and from second order coupled-cluster (CC2) calculations. The high ISC rate of BHQ-OAc and related compounds is traced back to involvement of almost energetically degenerate n,π* excited states that enable efficient ISC that obeys El-Sayed's rules.
authors.affiliation: Key Laboratory of Synthetic and Natural Functional Molecular Chemistry of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an, P. R. China. anini1984@163.com and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong S.A.R., P. R. China. phillips@hku.hk.
authors.forename: Jiani
authors.initials: J
authors.lastname: Ma
authors.affiliation: Interdisciplinary Center for Scientific Computing, University of Heidelberg, Im Neuenheimer Feld 205, 69120 Heidelberg, Germany. dreuw@uni-heidelberg.de.
authors.forename: Jan-Michael
authors.initials: JM
authors.lastname: Mewes
authors.affiliation: Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA.
authors.forename: Kyle T
authors.initials: KT
authors.lastname: Harris
authors.affiliation: Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA and New York University Abu Dhabi, PO Box 129188, Abu Dhabi, United Arab Emirates. timothy.dore@nyu.edu.
authors.forename: Timothy M
authors.identifier: http://orcid.org/0000-0002-3876-5012
authors.initials: TM
authors.lastname: Dore
authors.affiliation: Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong S.A.R., P. R. China. phillips@hku.hk.
authors.forename: David Lee
authors.initials: DL
authors.lastname: Phillips
authors.affiliation: Interdisciplinary Center for Scientific Computing, University of Heidelberg, Im Neuenheimer Feld 205, 69120 Heidelberg, Germany. dreuw@uni-heidelberg.de.
authors.forename: Andreas
authors.initials: A
authors.lastname: Dreuw