Absorption, fluorescence, and acid-base equilibria of rhodamines in micellar media of sodium dodecyl sulfate

作者：Obukhova Elena N; Mchedlov Petrossyan Nikolay O^*; Vodolazkaya Natalya A; Patsenker Leonid D; Doroshenko Andrey O; Marynin Andriy I; Krasovitskii Boris M

来源：Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy , 2017, 170: 138-144.

DOI：10.1016/j.saa.2016.07.002

• Rhodamine dyes
• Sodium n-dodecylsulfate micelles
• Ionization constants
• Fluorescence

Rhodamine dyes are widely used as molecular probes in different fields of science. The aim of this paper was to ascertain to what extent the structural peculiarities of the compounds influence their absorption, emission, and acid-base properties under unified conditions. The acid-base dissociation (HR+ reversible arrow R + H+) of a series of rhodamine dyes was studied in sodium n-dodecylsulfate micellar solutions. In this media, the form R exists as a zwitterion R-+/-. The indices of apparent ionization constants of fifteen rhodamine cations HR+ with different substituents in the xanthene moiety vary within the range of pK(a)(app) = 5.04 to 553. The distinct dependence of emission of rhodamines bound to micelles on pH of bulk water opens the possibility of using them as fluorescent interfacial acid-base indicators.

• 出版日期2017-1-5