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论文类型：期刊论文

发表时间：2020-03-18

发表刊物：Chemistry (Weinheim an der Bergstrasse, Germany)

收录刊物：PubMed

卷号：26

期号：16

页面范围：3591-3599

ISSN号：1521-3765

关键字：Tröger's bases,intersystem crossing,naphthalimides,photophysics,time-resolved spectroscopy

摘要：Intersystem crossing (ISC) was observed for naphthalimide (NI)-derived Tröger's base, and the ISC was confirmed to occur by a spin-orbital charge-transfer (SOCT) mechanism. Conventional electron donor/acceptor dyads showing SOCT-ISC have semirigid linkers. In contrast, the linker between the two chromophores in Tröger's base is rigid and torsion is completely inhibited, which is beneficial for efficient SOCT-ISC. Femtosecond transient absorption (TA) spectra demonstrated charge-separation and charge-recombination-induced ISC processes. Nanosecond TA spectroscopy confirmed the ISC, and the triplet state is long-lived (46 μs, room temperature). The ISC quantum yield is dependent on solvent polarity (8-41 %). The triplet state was studied by pulsed-laser-excited time-resolved EPR spectroscopy, and both the NI-localized triplet state and triplet charge-transfer state were observed, which is in good agreement with the spin-density analysis. The Tröger's base was confirmed to be a potent photodynamic therapy reagent with HeLa cells (EC50 =5.0 nm).© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.