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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Extremely large dipole moment in the excited singlet state of tris{[ p -(N,N-dimethylamino)phenylethynyl]duryl}borane
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Extremely large dipole moment in the excited singlet state of tris{[ p -(N,N-dimethylamino)phenylethynyl]duryl}borane

机译：三{[对-（N，N-二甲基氨基）苯基乙炔基]二烷基}硼烷的激发单重态下的极大偶极矩

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摘要

Solvent effects on the spectroscopic and photophysical properties of tris{[p-(N,N-dimethylamino)phenylethynyl]duryl}borane (TMAB) and tris[(phenylethynyl)duryl]borane (TPhB) were studied in detail. Both TMAB and TPhB exhibited broad and structureless absorption and fluorescence bands ascribed to the charge transfer (CT) transition between the π-orbital of the aryl group (π(aryl)) and the vacant p-orbital on the boron atom (p(B)): π(aryl)-p(B) CT. The fluorescence spectra of TMAB and TPhB were dependent on a solvent polarity, and the Stokes shifts of the compounds (Δν S) were shown to correlate linearly with a solvent polarity parameter: f(X) = (D_s 1)/(2D_s + 1) (n~2 1)/(2n~2 + 1) where D_s and n are the dielectric constant and refractive index of a solvent, respectively. The slope value of the ΔνS versus f(X) plot gave the excited singlet state dipole moment of TMAB or TPhB to be ～60 or ～30 D, respectively, demonstrating that the excited singlet state of TMAB possessed an extremely large dipole moment. The fluorescence quantum yields (φ_f) and lifetimes (τ_f) of the compounds were also dependent on f(X). Detailed analysis of the present results demonstrated that the photophysical properties of TMAB were governed by the magnitude of the fluorescence rate constant (k _f) and the k_f value decreased almost one-tenth with an increase in f(X), which was the primary origin of the f(X) dependences of φ_f and τ_f. The results were discussed in terms of the characteristic π(aryl)-p(B) CT excited states of the derivatives
机译：详细研究了溶剂对三{[对-（N，N-二甲基氨基）苯基乙炔基]二烷基]硼烷基}硼烷（TMAB）和三[（苯基乙炔基）二酰基]硼烷（TPhB）的光谱和光物理性质的影响。 TMAB和TPhB均显示出宽泛且无结构的吸收和荧光带，这归因于芳基的π轨道（π（芳基））和硼原子上的空位p轨道之间的电荷转移（CT）跃迁（p（B ））：π（芳基）-p（B）CT。 TMAB和TPhB的荧光光谱取决于溶剂极性，化合物的斯托克斯位移（ΔνS）与溶剂极性参数线性相关：f（X）=（D_s 1）/（2D_s + 1 ）（n〜2 1）/（2n〜2 +1）其中D_s和n分别是溶剂的介电常数和折射率。 ΔνS对f（X）图的斜率值使TMAB或TPhB的激发单重态偶极矩分别为〜60或〜30 D，表明TMAB的激发单重态具有极大的偶极矩。化合物的荧光量子产率（φ_f）和寿命（τ_f）也取决于f（X）。目前结果的详细分析表明，TMAB的光物理性质受荧光速率常数（k _f）的大小控制，并且k_f值随f（X）的增加而降低了近十分之一，这是主要的起源φ_f和τ_f的f（X）依赖关系。根据衍生物的特征π（芳基）-p（B）CT激发态讨论了结果

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