[Spectra of complexes Eu(III)-furoic acid]

Three europium complexes [Eu(FA)3 x 2H2O] x NO3 (4,4'-Hbpy), [Eu(FA)3 x phen]H2O and Eu(FA)2 x NO3 x phen have been synthesized (FA = alpha-furoate, phen = 1,10-phenanthroline, 4,4'-Hbpy = 4,4'-bipyridine). The compositions and structures of these complexes were determined with elemental analysis, IR, UV and luminescence spectra. The luminescence spectra of the Eu complexes in solution show that the intensity of the ternary complex [Eu(FA)3 x phen]H2O is higher than that of the quaternary complex Eu(FA)2 x NO3 x phen, and much higher than that of [Eu(FA)3 x 2H2O] x NO3 (4,4'-Hbpy). The measured lifetime is 0.46 ms for complex [Eu(FA)3 x 2H2O] x NO3 (4,4'-Hbpy). These measured lifetimes are 1.13 and 1.20 ms for complexes [Eu(FA)3 x phen]H2O and Eu(FA)2 x NO3 x phen, respectively. This phenomenon correlates with antenna effect of phen and luminescence quenching of coordinated water.