Spectroscopy and structure of [LnL3bipy] and [LnL3phen] complexes with CAPh type ligand dimethylbenzoylamidophosphate

Coordination compounds with general formulas [LnL3bipy] (Ln1) and [LnL3phen] (Ln2), where Ln=La-Nd, Sm-Yb, L−-phosphoro-azo β-diketone analog anion: [C6H5CONPO(OCH3)2]−, phen=1,10-phenanthroline, bipy=2,2′-bipyridine, were synthesized and characterized by means of IR, 1H NMR and high resolution UV-vis absorption and luminescence spectroscopy (emission, excitation spectra and emission decay times) at 300, 77 and 4.2 K. The thermal behavior and stability of EuIII and TbIII complexes were studied by thermogravimetric and differential thermal analyses. Single-crystal X-ray diffraction data showed that Pr1, Yb1 and La2, Eu2, Gd2, Yb2 crystalize in the monoclinic and triclinic systems, respectively with eight-coordinated lanthanide ions. The relation between the crystal structure and spectroscopic properties of the complexes are discussed. The EuIII and TbIII complexes exhibited a strong metal-centered emission with decay time 1.5-1.8 ms. Intrinsic quantum yields (QLnLn) equal 57 (Eu1) and 55% (Eu2). The TbIII complexes revealed a very efficient ligand-to-metal energy transfer at room and low temperatures.