A novel rare-earth nitronyl nitroxide radical complex as a high-efficiency sensor for Cr³⁺ and Cr₂O₇²⁻ ions in aqueous solutions

In this article, a new complex with formula [Eu(hfac)₃(NITPh-DOMe)₂] (1) (hfac =  hexafluoroacetylacetonate, NITPh-DOMe =2-(3′,4′-dioxylmethylene-phenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide) has been successfully synthesized. Central Eu(III) ions of complex 1 are eight coordinated by two NITPh-DOMe radicals and three hexafluoroacetylacetonate ligands. The luminescent explorations show that complex 1 with high sensitivity, selectivity, almost linear at low concentration and the low detection limit for detection of Cr³⁺ (1 μM) and Cr₂O₇²⁻ (0.1 μM) ions in aqueous solutions.