Complexation of Al(III) by 8-Hydroxyquinoline and Drastic Fluorescence Enhancement in Reverse Micelles
✍ Scribed by Isabelle Devol; Elisabeth Bardez
- Publisher
- Elsevier Science
- Year
- 1998
- Tongue
- English
- Weight
- 172 KB
- Volume
- 200
- Category
- Article
- ISSN
- 0021-9797
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✦ Synopsis
tives are metal ion extraction and fluorometric determination Complexation of Al III by 8-hydroxyquinoline and fluorescence of metal ions. One of the distinctive features of this combehavior of the quinolinate(s) were studied in reverse micellar pound family is its high versatility thanks to the possibility systems at low water content, and compared to aqueous media. of fine-tuning the solubility behavior and the selectivity with Two surfactants were used: one was cationic (CTAC: cetyltrimeththe substituents borne by the 8HQ skeleton. 8HQ itself shows ylammonium chloride) and the other was anionic (AOT: sodium a great affinity for organic media and a lack of selectivity bis(2-ethylhexyl)sulfosuccinate). The results obtained in the for metal cations. Its uncharged chelates are very poorly
soluble in water, but they can be solubilized in organic solshowed that complexation occurred very likely in the oil phase vents such as chloroform, for instance. A sulfonic acid suband no micellar effect was observed. On the contrary, in the presence of AOT, specific micellar effects were observed due to the stituent allows solubilization of the ligand and complexes in presence of the anionic polar heads: stabilization of the positively water. Thus 8-hydroxyquinoline-5-sulfonic acid (8HQS) charged 1:1 and 1:2 chelates, at the expense of the neutral waterand its derivatives are widely used in aqueous media. insoluble 1:3 chelate which is formed in aqueous solutions under Another characteristic of the 8HQ family is the fluorosimilar conditions; drastic fluorescence enhancement factors of genic behavior of the compounds, allowing fluorometric de-120 and 100 in AOT/heptane (W Å 1.5) and AOT/dichloromethtermination of metal cations (2-4). Many metal complexes ane (W Å 1.6), respectively. Such factors have never been reported of 8HQ and its derivatives, whether sulfonated or not, exhibit so far in either hydroorganic or direct micellar systems. In return, a marked fluorescence, whereas the ligands are themselves the length of time for the production of the complex(es) is invery poorly fluorescent or nonfluorescent except in strongly creased because of the microheterogeneity of the medium and the acidic or basic media. Such fluorogenic reagents then allow small sizes of the water pools.