title: Ultrafast investigation of photoinduced charge transfer in aminoanthraquinone pharmaceutical product.
abstract: We investigated the mechanism of intramolecular charge transfer and the following radiationless dynamics of the excited states of 1-aminoanthraquinone using steady state and time-resolved absorption spectroscopy combined with quantum chemical calculations. Following photoexcitation with 460 nm, conformational relaxation via twisting of the amino group, charge transfer and the intersystem crossing (ISC) processes have been established to be the major relaxation pathways responsible for the ultrafast nonradiative of the excited S1state. Intramolecular proton transfer, which could be induced by intramolecular hydrogen bonding is inspected and excluded. Time-dependent density functional theory (TDDFT) calculations reveal the change of the dipole moments of the S0and S1states along the twisted coordinate of the amino group, indicating the mechanism of twisted intra-molecular charge transfer (TICT). The timescale of TICT is measured to be 5 ps due to the conformational relaxation and a barrier on the S1potential surface. The ISC from the S1state to the triplet manifold is a main deactivation pathway with the decay time of 28 ps. Our results observed here have yield a physically intuitive and complete picture of the photoinduced charge transfer and radiationless dynamics in anthraquinone pharmaceutial products.
authors.affiliation: State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, Hubei 430071, China.
authors.forename: Song
authors.initials: S
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, Hubei 430071, China.
authors.forename: Simei
authors.initials: S
authors.lastname: Sun
authors.affiliation: State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, Hubei 430071, China.
authors.forename: Miaomiao
authors.initials: M
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, Hubei 430071, China.
authors.forename: Lian
authors.initials: L
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, Hubei 430071, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Zhang
mesh_terms: D000880:Anthraquinones / Q000737:chemistry*; D006801:Humans; D006860:Hydrogen Bonding; D007700:Kinetics; D008027:Light; D015394:Molecular Structure; D004364:Pharmaceutical Preparations / Q000737:chemistry*; D055668:Photochemical Processes; D011522:Protons; D011789:Quantum Theory; D013050:Spectrometry, Fluorescence; D055672:Static Electricity; D013997:Time Factors
chemical_list: D000880:Anthraquinones; D004364:Pharmaceutical Preparations; D011522:Protons; C049061:1-aminoanthraquinone