Cyclodextrin-porphyrin supramolecular sensitizer for mercury(II) ion Original Research Article

A new supramolecular sensitizer for mercury(II) ion based on a cyclodextrin/porphyrin inclusion complex has been proposed. In aqueous base solution, meso-tetraphenylporphyrin (TPP) emits weak fluorescence. In the presence of alkylated β-cyclodextrin, significant fluorescence enhancement is observed from TPP by forming a cyclodextrin/porphyrin inclusion complex. In addition, the formation of supramolecular complex causes a remarkable increase of the porphyrin metallation rate following the fluorescence quenching of TPP at its maximum emission wavelength. The quenching of TPP fluorescence at room temperature is fast and nearly complete upon Hg(II) interaction. Based on these experimental observations, a simple, fast and low-cost fluorometric method for determination of Hg(II) was developed. With the optimum conditions described, Hg(II) in water from 5.0×10−8 to 2.0×10−5 mol l−1 can be determined with a limit of detection of 2.0×10−9 mol l−1. The method was applied in the analysis of water samples with satisfactory results.