A boron dipyrromethene (BODIPY) derivative has been synthesized whereby a phenoxyl ring attached at the 3-position is bound through the oxygen atom to the boron center. This compound is structurally distorted, with the molecular surface being curved, and undergoes further geometrical perturbation at the excited singlet state level. Fluorescence is readily observed in solution at ambient temperature, with the quantum yield rising with increasing viscosity of the surrounding solvent. Dual-exponential decay kinetics are observed, corresponding to E-type delayed fluorescence. In solution, the emission yield falls with increasing temperature, but the opposite situation is found for the same compound dispersed in an amorphous sugar. These results are considered in terms of two radiationless decay channels. A viscosity-dependent avenue allows the fluorophore to function as a conventional fluorescent rotor for tracking changes in local rheology. A temperature-dependent channel leads to trapping within a new conformation, which is weakly coupled to the ground state but is able to repopulate the emitting state on a relatively slow time scale. Analysis of the experimental data allows estimation of some of the key kinetic parameters as a function of temperature.

中文翻译：

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结构扭曲的单链BODIPY衍生物的非辐射衰变通道

合成了硼二吡咯亚甲基（BODIPY）衍生物，其中在3位连接的苯氧基环通过氧原子结合到硼中心。该化合物的结构扭曲，分子表面弯曲，并在激发的单重态水平上经历了进一步的几何扰动。在环境温度下的溶液中很容易观察到荧光，量子产率随周围溶剂粘度的增加而增加。观察到双指数衰减动力学，对应于E型延迟荧光。在溶液中，发射产率随温度的升高而下降，但是对于分散在无定形糖中的相同化合物却发现了相反的情况。根据两个无辐射衰减通道来考虑这些结果。取决于粘度的途径允许荧光团用作常规荧光转子，以追踪局部流变学的变化。与温度有关的通道导致陷于新构象内，该构象与基态弱耦合，但能够在相对较慢的时间尺度上重新填充发射态。通过对实验数据进行分析，可以估算出一些关键动力学参数随温度的变化。