Synthesis and Luminescent Properties of Europium(III), Terbium(III), and Gadolinium(III) Complex Compounds with 1,2,3,4-Tetrahydroacridine-9-carboxylic Acid

Abstract— Complex compounds of europium(III), terbium(III), and gadolinium(III) with 1,2,3,4-tetrahydroacridine-9-carboxylic acid (HL) of composition LnL₃·nH₂O (n = 5–10) have been synthesized. The composition and structure of the acid and the resulting complex compounds were confirmed by the methods of NMR and IR spectroscopy, thermogravimetry, and complexometric titration. The europium(III) complex with this acid exhibits efficient luminescence. Toxicity risks and physicochemical parameters for the acid and europium(III) and gadolinium(III) complex compounds were predicted using the OSIRIS Property Explorer software.