Papadopoulos Ilias, Gutiérrez-Moreno David, McCosker Patrick M, Casillas Rubén, Keller Paul A, Sastre-Santos Ángela, Clark Timothy, Fernández-Lázaro Fernando, Guldi Dirk M
Department of Chemistry and Pharmacy & Interdisciplinary Center for Molecular Materials (ICMM), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstrasse 3, 91058 Erlangen, Germany.
Área de Química Orgánica, Instituto de Bioingeniería, Universidad Miguel Hernández, Avdade la Universidad s/n, Elche E-03202, Spain.
J Phys Chem A. 2020 Jul 16;124(28):5727-5736. doi: 10.1021/acs.jpca.0c04091. Epub 2020 Jul 7.
Triplet-excited-state energies of perylene-monoimides (PMIs) lie in the range 1.12 eV ± 2 meV when compared to singlet-excited-state energies of about 2.39 eV ± 2 meV; therefore, the corresponding naphthalene-linked was investigated as a novel singlet-fission (SF) material. Ultrafast transient absorption measurements demonstrated the (SS)-to-(TT) transformation and the involvement of a mediating step in the overall (TT) formation. The intermediate is a charge-transfer state that links the initial (SS) with the final (TT), and imposes charge-transfer character on both, which are thus denoted (SS) and (TT). At room temperature, the decorrelation and stability of (TT) is affected by the geminate triplet-triplet recombination (G-TTR) of the two triplets. Independent confirmation for G-TTR to afford up-converted (SS) in fsTA and nsTA measurements with , came from probing (T)s in triplet-triplet annihilation up-conversion (TTA-UC). The G-TTR channel, active in the at room temperature, is suppressed by working at either low temperatures (∼140 K) or in polar solvents (benzonitrile): Both scenarios assist in stabilizing (TT). As a consequence, the triplet quantum yields are 4.2% and 14.9% at room temperature and 140 K, respectively, in 2-methyltetrahydrofuran.
与单重激发态能量约为2.39 eV±2 meV相比，苝单酰亚胺（PMI）的三重激发态能量在1.12 eV±2 meV范围内；因此，研究了相应的萘连接物作为一种新型的单重态裂变（SF）材料。超快瞬态吸收测量表明了从（SS）到（TT）的转变以及在整个（TT）形成过程中介导步骤的参与。中间体是一种电荷转移态，它将初始的（SS）与最终的（TT）联系起来，并赋予两者电荷转移特性，因此分别表示为（SS）和（TT）。在室温下，（TT）的去相关和稳定性受到两个三重态的双生三重态-三重态复合（G-TTR）的影响。在fsTA和nsTA测量中，通过探测三重态-三重态湮灭上转换（TTA-UC）中的（T），对G-TTR在 时产生上转换（SS）进行了独立确认。在室温下于 中活跃的G-TTR通道，通过在低温（约140 K）或极性溶剂（苄腈）中工作而受到抑制：这两种情况都有助于稳定（TT）。结果，在2-甲基四氢呋喃中，室温下和140 K时的三重态量子产率分别为4.2%和14.9%。
