Effect of surfactants on the aggregation of pyronin B and pyronin Y in aqueous solution

Optical properties of xanthene based fluorescent dyes studied by stretched-film linear dichroism

“…( Figure 8a, parallel vertical stack arrangement, presumably with the substituents on alternating sides) peak. 11 As shown in Figure 4, the film LD from the most dilute pyronin Y solution has a larger positive LD component at 551 nm and a smaller one at 515 nm. When the stock solution concentration is increased and dimer 15 or oligomers dominate the spectrum, a single positive LD band at 501 nm dominates (it is at ~509 nm in the absorbance) with intensity at both higher and lower energy relative to the monomer.…”

“…These conclusions are consistent with the polyvinyl alcohol film polarized absorbance and the Pariser-Parr-Pople calculations of Okubo et al 12 30 The wavelength maximum for pyronin B monomer is deemed to be at 552 nm and for the H-aggregates at 520 nm. 11 The pyronin B LD spectra of Figure 5 show comparatively little shape change with increasing concentration until 0.1 mg/mL at which point negative high-energy and positive low energy intensities 35 become apparent. The detectable monomer absorbance signals all have positive LD so are long axis polarized.…”

Dye aggregation and influence of pre-micelles on heterogeneous catalysis: A photophysical approach

“…The dimer formation is characterized by a large spectral change in the absorption spectrum around the main absorption peak in the visible spectrum (absorption decreases and a blue shifted shoulder appears), which characterizes the aggregation of dyes [6]. Relative to the dimerization, it is established that H (sandwich aggregates) and J (head-to-tail aggregates) [7] are possible conformation of dimers [8]. H-aggregates promotes hypsochromic shift in the absorption spectrum, representing weakly fluorescent species while the J-aggregates are fluorescent and provokes bathochromic shift [8].…”

“…Relative to the dimerization, it is established that H (sandwich aggregates) and J (head-to-tail aggregates) [7] are possible conformation of dimers [8]. H-aggregates promotes hypsochromic shift in the absorption spectrum, representing weakly fluorescent species while the J-aggregates are fluorescent and provokes bathochromic shift [8].…”

The molecular aggregation of pyronin Y in natural bentonite clay suspension

“…Recently, Reija et al [35] investigated photophysical properties of the inclusion complexation of pyronin dyes with native b-cyclodextrins (b-CD) in different solvents. In another study, Onganer and Arik [36] and Arik et al [37] showed that pyronin dyes in various media formed H-aggregates with negatively charged colloidal SiO 2 and sodiumdodecylsulphate (SDS) below the critical micelle (cmc) concentration in aqueous solution. However, the number of studies on the interactions between pyronin dyes and clay minerals in an aqueous suspension are limited.…”