An efficient and selective flourescent chemical sensor based on 5-(8-hydroxy-2-quinolinylmethyl)-2,8-dithia-5-aza-2,6-pyridinophane as a new fluoroionophore for determination of iron(III) ions. A novel probe for iron speciation

A novel fluorescent chemical sensor for the highly sensitive and selective determination of Fe3+ ions in aqueous solutions is prepared. The iron sensing system was prepared by incorporating 5-(8-hydroxy-2-quinolinylmethyl)-2,8-dithia-5-aza-2,6-pyridinophane (L) as a neutral Fe3+-selective fluoroionophore in the plasticized PVC membrane containing sodium tetraphenylborate as a liphophilic anionic additive. The response of the sensor is based on the strong fluorescence quenching of L by Fe3+ ions. At pH 5.5, the proposed sensor displays a calibration curve over a wide concentration range from 6.0 × 10−4 to 1.0 × 10−7 M, with a relatively fast response time of less than 2 min. In addition to a high stability and reproducibility, the sensor shows a unique selectivity toward Fe3+ ion with respect to common coexisting cations. The proposed fluorescence optode was applied to the determination of iron(III) content of straw of rice, spinach and different water samples. The fluorescent sensor was also used as a novel probe for Fe3+/Fe2+ speciation in aqueous solution.

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► Preparation of a novel fluorescent sensor for sensitive and selective determination of Fe3+ ions.
► 5-(8-Hydroxy-2-quinolinylmethyl)-2,8-dithia-5-aza-2,6-pyridinophane as fluoroionophore.
► Highly selective, sensitive and fast recognition of Fe3+ ions.
► Application to determination of iron(III) content of straw of rice, spinach and water samples.
► Use of the fluorescent sensor for Fe3+/Fe2+ speciation in aqueous solutions.