Investigation of excited singlet state properties of 8-hydroxyquinoline and its derivatives by fluorescence spectrometry

Abstract

Excitation and fluorescence spectra, excited singlet state, protolytic equilibrium constants for the equilibria between the cations and zwitterions, fluorescence quantum yields, and fluorescence limits of detection for 8-hydroxyquinoline and 29 of its derivatives are given. The derivatives studied include fluoro, chloro, bromo, iodo, sulfo, and thiocyano substituents in either the 5-or the 7-positions on the ring or in both positions and methylation of the phenolic oxygen at the 8-position on the ring. Excited singlet state pK,* values range from -6.2 for the 5-iodo-7-sulfo-8-hydroxyquinoline to -9.6 for the 5,7-disulfo-8-hydroxyquinoline. Analytical detection limits for the 8-hydroxyquinoline and its derivatives in concentrated sulfuric or perchloric acid were between 10-6 to 10-EM. Fluorescence quantum yields varied as expected from a high value (0.31) for 8-hydroxyquino-

N,N-Dicyclohexyl-2-(5,7-dibromoquinolin-8-yloxy)acetamide

“…For related literature, see: Allen et al (1987); Bratzel et al (1972); Li et al (2005); Patel & Patel (1999); Wen et al (2005).…”

“…8-Hydroxyquinoline and its derivatives have found extensive application as analytical reagents, e.g. in absorption spectrophotometry, fluorimetry, solvent extraction and partition chromatography (Bratzel et al, 1972). Some 8-hydroxyquinoline derivatives and their complexes with transition metals demonstrate antibacterial activity (Patel & Patel,1999).…”

2-Aminoquinolin-8-ylp-toluenesulfonate

“…8-Hydroxyquinoline derivatives show a wide spectrum of properties as analytical reagents, owing to their ability to form complexes with many metal ions (Bratzel et al, 1972). In addition, 8-hydroxyquinoline (8-HQ) has received continuous attention as a platform for the construction of a number of selective and efficient fluoroionophores (Youk et al, 2004).…”

A rapid and simple 8‐quinolinol‐based fluorescent stain of phosphoproteins in polyacrylamide gel after electrophoresis

“…8‐Q is a monoprotic bidentate chelating agent that has been utilized as a versatile reagent in analytical chemistry for metal ion extraction and fluorometric determination . It is known that 8‐Q itself does not exhibit fluorescence in neutral aqueous solution, whereas strong fluorescence can be observed upon binding to aluminum ions (Al 3+ ) (Fig.…”