Föller Jelena, Marian Christel M
Institute of Theoretical and Computational Chemistry, Heinrich Heine University Düsseldorf , Universitätsstr. 1, D-40225 Düsseldorf, Germany.
J Phys Chem Lett. 2017 Nov 16;8(22):5643-5647. doi: 10.1021/acs.jpclett.7b02701. Epub 2017 Nov 7.
High-level quantum chemical calculations, presented in this Letter, show that the unusual luminescence properties of the high-performance thermally activated delayed fluorescence emitter CMA1, observed recently by Di et al. [ Science 2017, 356, 159-163 ], can be explained without resorting to the rotationally assisted spin-state inversion mechanism proposed by these authors. Multiconfiguration and relativistic effects lead to fast and efficient thermal equilibration of the excited singlet and triplet populations of this linear gold complex even for coplanar orientations of the ligands. The calculations predict S ⇝ T intersystem crossing outcompetes the submicrosecond fluorescence by 2 orders of magnitude, thus quenching prompt fluorescence. The significant time- and environment-dependent shifts of the CMA1 luminescence, observed in experiment, are attributed to effects of (hindered) solvent reorganization.
在本信函中展示的高水平量子化学计算结果表明，Di等人[《科学》2017年，第356卷，第159 - 163页]最近观察到的高性能热激活延迟荧光发射体CMA1的异常发光特性，无需借助这些作者提出的旋转辅助自旋态反转机制即可得到解释。即使对于配体的共面取向，多组态和相对论效应也会导致这种线性金配合物的激发单重态和三重态布居快速而有效地实现热平衡。计算预测，从单重态到三重态的系间窜越比亚微秒级荧光快2个数量级，从而淬灭即时荧光。实验中观察到的CMA1发光显著的时间和环境依赖性位移归因于（受阻的）溶剂重组效应。
