Some Spectral Studies of the Aqueous Solution of Pyronine G

Abstract

Th effect of inorganic anions on the dimerization constant of pyronine G in an aqueous solution was examined. It was found that the effect is very specific and can not be explained simply by the effect of the ionic strength. The analysis led to the conclusion that a dimer exists as an ion-pair with the anions attached laterally to dye ions instead of being sandwiched between two dye ions. The change of absorption spectra in the alkaline solution was interpreted to be due to the formation of carbinol, and from its analysis the formation constant of carbinol was determined. Carbinol was found to have also its proper fluorescence, and from the pH change of fluorescence spectra the formation constant of carbinol was again decided, the value of which coincided well with that obtained from the absorption spectra.

Specific Interactions in the Inclusion Complexes of Pyronines Y and B with β-Cyclodextrin

“…When compared to rhodamines, pyronines have similar photophysical properties which are much influenced by the aggregation of the dyes. − However, the lack of a substituent at the C9 position of the xanthene ring allows reversible hydrolysis of pyronine cations into the corresponding xanthydrols, which show blue-shifted fluorescence. , Even in basic media, this process is quite slow, but it is responsible for the observed chemical instability of pyronines in aqueous solution. Comparing the two pyronines under study, PB shows much higher reactivity with water than PY, which is more stable.…”

Excitations of Pyronin Y and Pyronin B Dyes in Aqueous Solution: Comparative Theoretical Analysis

“…Using optical methods, it was found that, in addition to non-covalent binding to nucleic acids [2,3,[8][9][10], PY and PB are also capable of forming non-covalent complexes with proteins [11], glucose [5], cyclodextrins [12], as well as with clay [13], nanoparticles [14,15] and nanocomposites [16]. Spectrophotometry has also been applied to study PY [10,12,[17][18][19][20][21][22][23][24] and PB [12,18,24] aggregations and heteroassociation [25]. The optical properties of the dyes have also been studied experimentally in sufficient detail, both in films [26] and in various solvents [27][28][29][30][31][32][33].…”

“…At the same time, the shape of the spectrum reflects the pattern of the excited states of the molecule and the transitions between them [39]. Thus, the absorption spectra of PY and PB both in an aqueous solution [2,10,23,24,33] and in non-aqueous solvents [2,28,31] contain a shortwavelength shoulders. Some authors [33] traditionally consider them to be dimeric.…”

Aggregation in aqueous solution of the dye pyronine G

“…For example, reported molar absorptivities for dilute aqueous solutions at 547 nm range from 1.2 x lo4 dm3 mol-1 cm-l [ref. (7)] to 10.7 x lo4 dm3 mol-1 cm-l [ref. (6)].…”