Properties and Evolution of Emission in Molecular Aggregates of a Perylene Ammonium Derivative in Polymer Matrices
Properties and Evolution of Emission in Molecular Aggregates of a Perylene Ammonium Derivative in Polymer Matrices
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聚合物基质中苝铵衍生物分子聚集体的发射特性和演变
DOI：
10.1039/c5pp00196j
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
Syoji Ito and Hiroshi Miyasaka
中科院分区：
文献类型：
--
作者：
Fuyuki Ito;Hirofumi Sato;Yuri Ugachi;Narumi Oka;Syoji Ito and Hiroshi Miyasaka
采用稳态和时间分辨光谱方法研究了苝铵衍生物（PeryAm）聚集体的尺寸依赖性荧光特性。水溶液中聚合态的定量分析表明，聚合是通过PeryAm的二聚体单元进行的。水溶液制备的PVA膜中聚集体的荧光随着母液中PeryAm浓度的增加而不断红移，而吸收光谱几乎保持相同的波段形状。聚集体在PVA膜中的荧光各向异性值依赖于监测波长，且在脉冲激发后较长波长的荧光时间曲线迅速增加。这些结果表明有效的能量转移到团聚体的稳定位点。荧光显微镜图像显示聚集体在聚乙烯醇薄膜中被分离，并且发射的颜色取决于聚集体的大小。在稳态辐照下，聚集体的发射色由绿色变为黄色，这是由于一小簇PeryAm与绿色发射相结合，形成了黄色聚集体。在这些结果的基础上，我们讨论了团聚体中团聚和尺寸依赖性发射的机制和动力学。
Size-dependent fluorescent properties of aggregates of a perylene ammonium derivative (PeryAm) were studied by steady-state and time-resolved spectroscopic methods. Quantitative analyses of aggregated states in aqueous solution indicated that the aggregation proceeded through dimer units of PeryAm. The fluorescence of the aggregate in the PVA film prepared from the aqueous solution continuously redshifted with an increase in the concentration of PeryAm in the mother liquor while keeping the absorption spectra in almost the same band shapes. Fluorescence anisotropy values of aggregates in the PVA film were dependent on the monitoring wavelength, and time profiles of the fluorescence at longer wavelengths showed a rapid increase just after the pulsed excitation. These results indicated efficient energy transfer to the stable sites in aggregates. Fluorescence microscopy images showed that aggregates were segregated in the PVA film and the color of the emission was dependent on the size of the aggregate. Under the steady-state irradiation, the emission color of the aggregates changed from green to yellow, which was attributable to the association of a small cluster of PeryAm with the green emission resulting in the formation of yellow-colored aggregates. On the basis of these results, we have discussed the mechanisms and dynamics of the aggregation and size-dependent emission in aggregates.