A water-soluble perylene ammonium derivative was synthesized and its fluorescence spectra in solution and in polymer matrices were measured as a function of concentration. The concentration-dependent fluorescence spectral change in polymer films is useful for probing the initial processes of crystal nuclei growth by matrix isolation and/or freezing.
5Size-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. 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 10 absorption spectra 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 in longer wavelength showed fast rise just after the pulsed excitation. These results indicated the efficient energy transfer to the stable sites in aggregates. Fluorescence microscope images showed aggregates were segregated in the PVA film and the color of the emission was dependent on the size of the aggregate.
15Under the steady-state irradiation, the emission color of the aggregates was 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 discussed the mechanisms and the dynamics of the aggregation and size-dependent emission in aggregates.
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