Chelate-free turn-on-type fluorescence detection of trivalent metal ions

Trivalent metal ions are essential elements in materials and life sciences. To date, fluorescence is the gold standard for the detection of trivalent metal ions, which form a complex with fluorescent chelate ligands (Lewis base type). In this study, we report pH-responsive fluorescent probes for the selective detection of trivalent metal ions that utilize a new chelate-free approach using Bronsted base-type probes. Moreover, an X-ray structure of the outer-sphere aluminum(III) aqua complex coordinated by the fluorescent probes through hydrogen bonds was discovered. The outer-sphere complex consisting of an Al(III) aqua complex and protonated cationic probe showed cation-cation coordination.

Automated summary

Fluorescence is the gold standard for detecting trivalent metal ions. This study presents a new chelate-free approach using Bronsted base-type probes for the selective detection of trivalent metal ions, and also discovers the X-ray structure of an outer-sphere aluminum(III) aqua complex coordinated by fluorescent probes via hydrogen bonds.