Shafikov Marsel Z, Zaytsev Andrey V, Suleymanova Alfiya F, Brandl Fabian, Kowalczyk Aleksandra, Gapińska Magdalena, Kowalski Konrad, Kozhevnikov Valery N, Czerwieniec Rafał
Institut für Physikalische und Theoretische Chemie, Universität Regensburg, Universitätsstrasse 31, Regensburg D-93053, Germany.
Department for Technology of Organic Synthesis, Institute of Chemical Technology, Ural Federal University, Mira 19, Ekaterinburg 620002, Russia.
J Phys Chem Lett. 2020 Aug 6;11(15):5849-5855. doi: 10.1021/acs.jpclett.0c01276. Epub 2020 Jul 10.
A dinuclear iridium(III) complex shows dual emission consisting of near infrared (NIR) phosphorescence (λ = 714 nm, CHCl, = 300 K) and green fluorescence (λ = 537 nm). The NIR emission stems from a triplet state (T) localized on the ditopic bridging ligand (LC). Because of the dinuclear molecular structure, the phosphorescence efficiency (Φ = 3.5%) is high compared to those of other known red/NIR-emitting iridium complexes. The weak fluorescence stems from the lowest excited singlet state (S) of LC character. The occurrence of fluorescence is ascribed to relatively slow intersystem crossing (ISC) from state S (LC) to the triplet manifold. The measured ISC rate corresponds to a time constant τ of 2.1 ps, which is an order of magnitude longer than those usually found for iridium complexes. This slow ISC rate can be explained in terms of the LC character and large energy separation (0.57 eV) of the respective singlet and triplet excited states. is internalized by live HeLa cells as evidenced by confocal luminescence microscopy.
一种双核铱（III）配合物表现出由近红外（NIR）磷光（λ = 714 nm，CHCl， = 300 K）和绿色荧光（λ = 537 nm）组成的双重发射。近红外发射源于位于双齿桥连配体（LC）上的三重态（T）。由于双核分子结构，与其他已知的发红光/近红外光的铱配合物相比，磷光效率（Φ = 3.5%）较高。弱荧光源于具有LC特征的最低激发单重态（S）。荧光的出现归因于从态S（LC）到三重态的相对较慢的系间窜越（ISC）。测得的ISC速率对应于2.1 ps的时间常数τ，这比通常在铱配合物中发现的时间常数长一个数量级。这种缓慢的ISC速率可以根据LC特征以及相应单重态和三重态激发态的大能量间隔（0.57 eV）来解释。通过共聚焦发光显微镜证明，其被活的HeLa细胞内化。
