Synthesis and Luminescent Properties of Eu3+ and Tb3+ Complexes with Coumarin-3-carboxylic Acids

New Eu3+ and Tb3+ complex compounds [Ln(H2O)2L2]Cl∙H2O were synthesized on the basis of coumarin-3-carboxylic acid and its derivatives. Composition and structure of the ligands and the complex compounds were confirmed by NMR and IR spectroscopy, thermogravimetry, and complexometric titration. Europium(III) coordination compounds with coumarin-3-carboxylic and 6-nitrocoumarin-3-carboxylic acids show effective luminescence.