Lanthanide complexes with diethyl(2-oxopropyl) phosphonate and diethyl(2-oxo-2-phenylethyl) phosphonate ligands

Abstract

Abstract Ln 3+ complexes with the phosphonate ligands: diethyl(2-oxopropyl) phosphonate [CH 3 C(O)CH 2 P(O)(OC 2 H 5 ) 2 ] (OPP) and diethyl (2-oxo-2-phenylethyl) phosphonate [C 6 H 5 C(O)CH 2 P(O)(OC 2 H 5 ) 2 ] (DEPP) were synthesized and characterized. Complexation studies and spectral characterizations are performed. Based on the Nd 3+ absorption spectra, using computer-assisted target factor analysis, the stability constants of Nd-OPP complexes in solution were determined to be log β 11 = 2.8 ± 0.4 and log β 12 = 5.0 ± 0.7. Luminescence intensities, lifetimes, τ , and quantum yields, Φ , of the Eu 3+ and Tb 3+ ions in the complexes were measured. The most intense luminescence was observed in the case of the Tb/DEPP system. Emission enhancements were observed for Tb 3+ and Eu 3+ complexes in acetonitrile solutions, which occurred as a result of sensitized luminescence. These observed luminescence intensities were over two orders of magnitude larger than those for the uncomplexed Ln(III) ions. The complexes of Ln/L/NO 3 , obtained in oil forms from ethanol at room temperature, were characterized by elemental analysis, IR spectroscopy, and luminescence lifetime measurements. The composition of the complexes studied is suggested to be LnL 2 (NO 3 ) 3 , with monodentate coordination by the phosphoryl group.