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2 papers
Spectroscopy of condensed matter
Photophysical processes in molecules of halogenated fluorescein derivatives in anionic reverse micelles
O. I. Volkovaa,
A. A. Kuleshovaa,
B. N. Korvatovskiĭb,
A. M. Saletskiia a Faculty of Physics, Lomonosov Moscow State University
b Lomonosov Moscow State University, Faculty of Biology
Abstract:
We studied the photophysical processes of halogenated fluorescein derivatives (eosin (E), erythrosine (ER), and Rose Bengal (RB)) in aqueous micellar solutions using dynamic light scattering and stationary and time-resolved fluorescence spectroscopy. The introduction of dye molecules into reverse AOT micelles causes an increase in their hydrodynamic radii
$R_{h}$. The kinetics of fluorescence of the studied dye molecules in reverse micelles was investigated. The average time
$\langle\tau\rangle$ of the excited state decreases with increasing
$R_h$ for eosin, erythrosine, and Rose Bengal, which is associated with an increase in the mobility of water molecules and a weakening of the effect of geometric limitation of dye molecules. The degrees of fluorescence anisotropy
$r$ of dye molecules in reverse micelles were measured; the
$r$ values in micellar systems are greater than in aqueous solutions and decrease with increasing
$R_{h}$. For the studied dye molecules in micellar systems, the rotational correlation time
$\theta$ was determined, which decreases for all studied dyes with increasing
$R_{h}$, which indicates a decrease in the microviscosity of a limited aqueous medium inside the micelle. It is found that $\theta_{\mathrm{E}}>\theta_{\mathrm{ER}}>\theta_{\mathrm{BR}}$; that is, the effect of the internal heavy atom appears in the value of the rotational correlation time.
Keywords:
dyes, halogenated fluorescein derivatives, reverse micelles, dynamic light scattering, spectra, fluorescence anisotropy, average excited state lifetime, rotational correlation time. Received: 24.06.2020
Revised: 31.08.2020
Accepted: 04.09.2020
DOI:
10.21883/OS.2020.12.50319.181-20
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