title: Photophysical Properties of Intramolecular Charge Transfer in a Tribranched Donor-π-Acceptor Chromophore.
abstract: The photophysical properties of intramolecular charge transfer (ICT) in a novel tribranched donor-π-acceptor chromophore, triphenoxazine-2,4,6-triphenyl-1,3,5-triazine (tri-PXZ-TRZ), with thermally activated delayed fluorescence character was investigated in different aprotic solvents by steady-state spectroscopy and femtosecond and nanosecond transient absorption spectroscopy measurements. Increasing the solvent polarity led to a significant increase in the Stokes shift. The large Stokes shift in highly polar solvents was attributed to ICT properties upon excitation; this resulted in a strong interaction between the tri-PXZ-TRZ molecule and the surrounding solvent, which led to a strong solvation process. Quantum-chemical calculations and changes in the dipole moment showed that this compound has a large degree of ICT. Furthermore, an apolar environment helped to preserve the symmetry of tri-PXZ-TRZ and to enhance its emission efficiency. The femtosecond and nanosecond transient absorption spectroscopy results indicated that the excited-state dynamics of this push-pull molecule were strongly influenced by solvent polarity through the formation of a solvent-stabilized ICT state. The excited-state relaxation mechanism of tri-PXZ-TRZ was proposed by performing target model analysis on the femtosecond transient absorption spectra. In addition, the delayed fluorescence of tri-PXZ-TRZ was significantly modulated by a potential competition between solvation and intersystem crossing processes.
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190 (China).
authors.forename: Jiangpu
authors.initials: J
authors.lastname: Hu
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190 (China).
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190 (China).
authors.forename: Huaning
authors.initials: H
authors.lastname: Zhu
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190 (China).
authors.forename: Shuhai
authors.initials: S
authors.lastname: Qiu
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190 (China).
authors.forename: Guiying
authors.initials: G
authors.lastname: He
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190 (China). xzzhu@iccas.ac.cn.
authors.forename: Xiaozhang
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190 (China). andong@iccas.ac.cn.
authors.forename: Andong
authors.initials: A
authors.lastname: Xia
mesh_terms: D011789:Quantum Theory; D012997:Solvents / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D014227:Triazines / Q000737:chemistry*
chemical_list: D012997:Solvents; D014227:Triazines
keywords: charge transfer; donor-π-acceptor; reaction mechanisms; solvation; solvatochromism