A self-organized ensemble of fluorescent 3-hydroxyflavone-Al (III) complex as sensor for fluoride and acetate ions

• Published in: Journal of fluorescence 2007-01, Vol.17 (1), p.1-5
• Main Authors: Sathish, Sai, Narayan, Govindh, Rao, Nageswara, Janardhana, Chelli
• Format: Article
• Language: English
• Subjects: Acetates - chemistry; Aluminum - chemistry; Flavones - chemistry; Fluorides - chemistry; Ions - analysis; Ligands; Methanol - chemistry; Molecular Structure; Spectrometry, Fluorescence
• ISSN: 1053-0509; 1573-4994
• DOI: 10.1007/s10895-006-0137-1

Aluminum chloride addition results in a self-organized TURN-ON fluorescence of 3-hydroxyflavone (3HF) by a complexation reaction in MeOH and subsequent ligand exchange reaction with fluoride or acetate ions causes a fluorescence TURN-OFF of this complex, delivering a quantitative estimation route for fluoride and acetate ions. The ternary complex of 3HF with Al (III), a hard acid provides for a sensitive signalling system for fluoride ion, a hard base in the concentration range from 6 muM to 50 mM by a concerted co-ordination of fluoride ion involving an intermediate mechanistic pathway, while the complex is sensitive to acetate addition between 0-68 muM. The ligand exchange reaction of Al (3HF)(2) complex by fluoride or acetate ion, without interference from other common anions, has been investigated by UV-visible and fluorescence spetroscopies. The structure of the in-situ intermediate isolated at higher Al (3HF)(2) complex and acetate concentrations was inferred from the FT-IR spectrum and ESI-MS of the sample.