Development of a fluorescent chelating ligand for scandium ion having a Schiff base moiety

A fluorescent ligand, 1-(2-hydroxy-3-methoxybenzaldehyde)-4-aminosalicylhydrazone (HMB-ASH), was newly designed and synthesized, and its fluorescence characteristics for metal ions were investigated in the pH range 3.0–10.5 (at a difference of 0.5 for each metal).After testing 31 different metal ions, it was found that HMB-ASH was able to emit fluorescence intensely at 512 nm with an excitation wavelength of 353 nm in the presence of Sc3+, one of the rare earth metals, at pH values around 3.5 and 8.0. The other metal ions hardly showed fluorescence with HMB-ASH. The fluorescence was more intense at pH 8.0, and the detection limit of Sc3+ in a buffer solution (pH 8.0) was approximately 18.8 nmol L−1 (0.85 ppb).

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A novel fluorescent ligand, HMB-ASH, for Sc3+ was developed. ► The fluorescence at 512 nm was most intense in the buffer at pH 8.0. ► Binging ratio of HMB-ASH to Sc3+ was 1:1. ► Few foreign ions except Fe3+ could interfere with the complex of HMB-ASH to Sc3+. ► The interference by Fe3+ was suppressed by adding thiocyanato ion.