NMR and luminescence spectroscopy study of the formation of mixed europium β-diketonate complexes with trifluoroacetic acid in nonaqueous solutions

The ligand substitution in Eu(AA)(3) center dot Phen-CDCl(3)-TFA systems, where AA is acetylacetone, Phen is 1,10-phenanthroline, and TFA is trifluoroacetic acid was studied at various molar ratios (m) of competing ligands (m = TFA/AA) using NMR ((1)H, (19)F) and luminescence spectroscopy. The formation of mixed Eu(AA)(2)(TFA) center dot Phen and Eu(AA)(TFA)(2) center dot Phen complexes in the resultant solutions was attested. The luminescence spectra were studied. The competitive capacity of TFA was ascertained to be higher than that of AA. Depending on the m value, the substitution of acido ligands was shown to occur successively according equations Eu(AA)(3) center dot Phen + (TFA) (n) = Eu(AA)(3 - n) (TFA) (n) center dot Phen + (AA) (n) (n = 1, 2, 3).