Fluorescence Enhancement by Symmetry Breaking in a Twisted Triphenylene Derivative
Fluorescence Enhancement by Symmetry Breaking in a Twisted Triphenylene Derivative
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DOI：
10.1021/jp106622n
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发表时间：
2010-12-30
影响因子：
2.9
通讯作者：
Samuel, Ifor D. W.
中科院分区：
文献类型：
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作者：
Levell, Jack W.;Ruseckas, Arvydas;Samuel, Ifor D. W.
1,4,5,8,9,12-六甲基苯并菲 (HMTP) 在固态下表现出高达 31% 的光致发光量子产率 (PLQY)，使其在发光应用中受到关注。通过使用时间分辨和稳态发光、PLQY 和摩尔吸收系数测量，研究了 HMTP 的详细光物理性质。与未取代的苯并菲的情况相比，荧光和吸收的跃迁偶极矩得到了增强，导致辐射衰减率增加了 20 倍。这归因于空间拥挤引起的必然扭曲结构导致苯并菲对称性的破坏。此外，结果表明，HMTP 在溶液、粉末和薄膜中表现出相似的光致发光能量，表明其光致发光能量有所降低。由于这种扭曲结构，与苯并菲的情况相比，分子间π堆积的倾向。这项工作还开发了一种通过使用校准的光电二极管与未校准的 CCD 光谱仪相结合来计算粉末光致发光量子产率的方法。
1,4,5,8,9,12-Hexamethyltriphenylene (HMTP) shows a high photoluminescence quantum yield (PLQY) of 31% in the solid state, making it of interest for luminescence applications. The detailed photophysical properties of HMTP have been investigated by using time-resolved and steady-state luminescence, PLQY, and molar absorption coefficient measurements. An enhancement of the transition dipole moment for fluorescence and absorption was demonstrated compared to the case of unsubstituted triphenylene, which resulted in a 20-fold increase in the radiative decay rate. This is attributed to a breaking of triphenylene symmetry as a result of the necessarily twisted structure induced by steric crowding. In addition, it was shown that HMTP shows similar photoluminescence energies in solution, powder, and film, indicating a reduced. propensity for intermolecular pi-stacking compared to the case of triphenylene, as a result of this twisted structure. This work also develops a method for calculating the photoluminescence quantum yield of powders by using a calibrated photodiode in combination with an uncalibrated CCD spectrometer.