Hetzer Constantin, Basel Bettina S, Kopp Sebastian M, Hampel Frank, White Fraser J, Clark Timothy, Guldi Dirk M, Tykwinski Rik R
Department of Chemistry and Pharmacy and Interdisciplinary Center for Molecular Materials (ICMM), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Nikolaus-Fiebiger-Strasse 10, 91058, Erlangen, Germany.
Department of Chemistry and Pharmacy and Interdisciplinary Center for Molecular Materials (ICMM), FAU, Egerlandstrasse 3, 91058, Erlangen, Germany.
Angew Chem Int Ed Engl. 2019 Oct 21;58(43):15263-15267. doi: 10.1002/anie.201907221. Epub 2019 Sep 18.
A tetrameric pentacene, PT, has been used to explore the effects of exciton delocalization on singlet fission (SF). For the first time, triplet decorrelation through intramolecular triplet diffusion was observed following SF. Transient absorption spectroscopy was used to examine different decorrelation mechanisms (triplet diffusion versus structural changes) for PT and its dimeric equivalent PD on the basis of the rate and activation barrier of the decorrelation step. Charge-separation experiments using tetracyano-p-quinodimethane (TCNQ) to quench triplet excitons formed through SF demonstrate that enhanced intersystem crossing, that is, spin catalysis, is a widely underestimated obstacle to quantitative harvesting of the SF products. The importance of spatial separation of the decorrelated triplet states is emphasized, and independent proof that the decorrelated triplet pair state consists of two (T ) states per molecule is provided.
一种四聚并五苯（PT）已被用于探究激子离域对单线态裂变（SF）的影响。首次观察到在SF之后通过分子内三重态扩散实现的三重态去关联。基于去关联步骤的速率和活化能垒，利用瞬态吸收光谱研究了PT及其二聚体等效物PD的不同去关联机制（三重态扩散与结构变化）。使用四氰基对苯二醌二甲烷（TCNQ）淬灭通过SF形成的三重态激子的电荷分离实验表明，增强的系间窜越，即自旋催化，是定量收集SF产物时一个被广泛低估的障碍。强调了去关联三重态态空间分离的重要性，并提供了独立证据证明去关联三重态对态由每个分子的两个（T）态组成。
