Study on initial processes of crystal nucleolus formation as probed by fluorescence spectral change due to the organic molecular assemblies

我们研究了由有机分子组装引起的荧光光谱变化所揭示的晶体核仁形成的初始过程。用溴化吡喃(Trimethyl-(2-oxo-2-pyrene-1-yl-ethyl)-ammonium)作为荧光染料分子。随着染料浓度的增加，PVA薄膜中的聚集体尺寸增大。在较低浓度(0.001mol%)的PVA膜中，PYAM的荧光光谱仅表现为单体发射。随着染料浓度的增加，荧光峰向红移，归属为二聚体或类准分子发射。荧光光谱的变化与膜中聚集体的形成有关。通过相分离形成的纳米晶体和/或聚集体被认为表现出依赖于结构域大小的荧光性质的分级变化(如连续反应)。我们还发现了在光照射下，吡喃纳米聚集体的荧光光谱发生了变化。它是由光诱导的PYAM聚集体溶解形成的。

We have studied on intial processes of crystal nucleolus formation as probed by fluorescence spectral change due to the organic molecular assemblies. Trimethyl-(2-oxo-2-pyrene-1-yl-ethyl)-ammonium bromide (PyAm) was used as a fluorescent dye molecule. The size of PyAm aggregates in the PVA thin films were increased with increasing dye concentration. The fluorescence spectra of PyAm in the PVA film at a lower concentration of 0.001mol% only showed the monomer emission. The fluorescence peak shifted to the red with increasing dye concentration, which was assigned to a dimer or excimer-like emission. Changes in the fluorescence spectra relate to the formation of aggregates in the films. The nano-crystals and/or aggregates formed by phase separation are presumed to show hierarchical change (like a consecutive reaction) of fluorescence property depending on the domain size. We also find the fluorescence spectral change of PyAm nano-aggregates by the photo irradiation. It is originated from the photoinduced dissolution of PyAm aggregates.