A ratiometric fluorescent chemosensor for Cr3+ based on monomer-excimer conversion of a pyrene compound

A pyrene compound (1) containing piperazine was synthesized and used as ratiometric fluorescent chemosensor to recognize Cr3+. The ratiometric fluorescent signal change of the chemosensor is on the basis of monomer-excimer conversion of 1 induced by Cr3+. As far as we know, it is the first ratiometric chemosensor based on pyrene that is developed for Cr3+. The analytical performance characteristics of the proposed Cr3+-sensitive chemosensor were investigated. The chemosensor can be applied to the quantification of Cr3+ with a linear range covering from 2.0 × 10−7 to 1.0 × 10−5 M with the detection limit is 4 × 10−8 M. The experiment results show that the response behavior of 1 towards Cr3+ is pH independent in medium condition (pH 6.0-8.0). Most importantly, the fluorescence changes of the chemosensor are remarkably specific for Cr3+ in the presence of other metal ions, which meet the selective requirements for practical application. Moreover, the response of the chemosensor toward Cr3+ is fast (response time less than 2 min). In addition, the chemosensor has been used for determination of Cr3+ in real sample such as river and pond water with satisfactory results.