A fluorescent chemosensor for silver ions based on porphyrin compound with high selectivity.

The design and synthesis of meso-tetra(p-methoxylpheny1)porphyrin (T(p-OCH(3))PPH(2)) and its application in fluorescent detections of Ag(I) in aqueous solution are reported. The fluorescence quenching of T(p-OCH(3))PPH(2) is attributed to the formation of a complex between T(p-OCH(3))PPH(2) and Ag(I) by 1:1 complex ratio (K=3.7 x 10(5)), which has been utilized as the basis of the fabrication of the Ag(I)-sensitive fluorescent chemosensor. The analytical performance characteristics of the proposed Ag(I)-sensitive chemosensor were investigated. The chemosensor can be applied to the quantification of Ag(I) with a linear range covering from 1.0 x 10(-7) to 5.0 x 10(-5)M with a detection limit of 2.5 x 10(-8)M. The experiment results show that the response behavior of T(p-OCH(3))PPH(2) towards Ag(I) is pH independent in medium condition(pH 4.0-8.0). Most importantly, the fluorescence changes of the chemosensor are remarkably specific for Ag(I) in the presence of other heavy and transition metal ions (even those that exist in high concentration), which meet the selective requirements for practical application. The proposed chemosensor has been used for direct measurement of Ag(I) content in river water samples with satisfying results, which further demonstrates its value of practical applications in environmental systems.