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The odd–even effect in luminescent [Eu2(L)3(H2O)x]⋅y(H2O) complexes with aliphatic dicarboxylate ligands (L: OXA, MAL, SUC, GLU, ADP, PIM, SUB, AZL, SEB, UND, and DOD, where x=2–6 and y=0–4), prepared by the precipitation method, was observed for the first time in lanthanide compounds. The final dehydration temperatures of the Eu3+ complexes show a zigzag pattern as a function of the carbon chain length of the dicarboxylate ligands, leading to the so‐called odd‐even effect. The FTIR data confirm the ligand–metal coordination via the mixed mode of bridge–chelate coordination, except for the Eu3+‐oxalate complex. XRD results indicate that the highly crystalline materials belong to the monoclinic system. The odd–even effect on the 4 f–4 f luminescence intensity parameters (Ω2 and Ω4) is explained by using an extension of the dynamic coupling mechanism, herein named the ghost‐atom model. In this method, the long‐range polarizabilities (α* ) were simulated by a ghost atom located at the middle of each ligand chain. The values of α* were estimated using the localized molecular orbital approach. The emission intrinsic quantum yield (QnormalLnormalnnormalLnormaln ) of the Eu3+ complexes also presented an the odd‐even effect, successfully explained in terms of the zigzag behavior shown by the Ω2 and Ω4 intensity parameters. Luminescence quenching due to water molecules in the first coordination sphere is also discussed and rationalized.

The design of efficient luminescent lanthanide materials with a wide range of different excitation wavelengths in the UVA, UVB, and UVC regions, as well as under sunlight exposure, is highly desirable for application as molecular light-converting devices. In this work, [Ln(fluf)3(L)] complexes (Ln3+: Eu, Gd, and Tb) and doped PMMA:(1%)Tb(fluf)3(L) films, where fluf stands for the flufenamate ligand and L is H2O, phen, tppo, topo, and dpso, were successfully prepared by a facile one-pot method, and their photophysical properties were also investigated. The Ln3+ compounds were characterized by elemental analysis, Fourier transform infrared absorption spectroscopy, thermogravimetric analysis, X-ray powder diffraction, and diffuse reflectance spectroscopy techniques. The Eu3+ complexes present very weak emission intensities at 300 K temperature, showing very low intrinsic quantum yield (Q Eu Eu) values due to a highly operative luminescence quenching by a low-lying ligand to metal charge transfer state. However, these values are significantly increased when obtained at low temperature (77 K). For Tb3+ complexes and the doped PMMA, polymeric films revealed an unprecedented bright emission under excitation at UVA, UVB, and UVC radiation. In addition, the doped polymers under sunlight exposure show the characteristic 5D4 → 7F6–0 transitions of the Tb3+ ion, exhibiting green emission color. These luminescent doped polymeric materials act as efficient energy harvesters and converters. Hence, the optical results show that the PMMA:(1%)Tb(fluf)3(L) photonic materials are highly versatile and desirable, presenting suitable application as efficient light-converting molecular devices and as luminescent solar concentrators.

The present report describes a new approach to stain bacteria by means of rare earth complexes. We demonstrate with selected Gram-negative and positive bacteria (Escherichia coli, Micrococcus luteus, Bacillus megaterium) that these microbes can be stained efficiently with derivatives of N-phenylanthranilic acid, flufenamic acid in particular, and Tb3+ ions. Hence, the inherent advantages of rare earth complexes, e.g. strong optical absorption (>50 000 L × M−1 × cm−1) due to the antenna effect, large Stokes’ shifts (~10 000 cm−1) and very long emission decay times (millisecond range), and, not least, enhanced photostability can be fully exploited in fluorescence microscopy and spectroscopy of the bacteria; foreseeably, these findings will also be useful in flow cytometry and ELISA techniques.

Efficiently luminescing spherical polymer particles (beads) in the nanoscale regime of up to approximately 250 nm have become very valuable tools in bioanalytical assays. Eu3+- complexes imbedded in polymethacrylate and polystyrene in particular proved to be extraordinarily useful in sensitive immunochemical and multi-analyte assays, and histo- and cytochemistry. Their obvious advantages derive from both, the possibility to realize very high ratios of emitter complexes to target molecules, and the intrinsically long decay times of the Eu3+-complexes, which allows an almost complete discrimination against bothersome autofluorescence via time-gated measuring techniques; the narrow line emission in conjunction with large apparent Stokes shifts are additional benefits with regard to spectral separation of excitation and emission with optical filters. Last but not least, a reasonable strategy to couple the beads to the analytes is mandatory. We have thus screened a variety of complexes and ancillary ligands; the four most promising candidates evaluated and compared to each other were β-diketonates (trifluoroacetylacetonates, R-CO-CH-CO-CF3, R = - thienyl, -phenyl, -naphthyl and -phenanthryl); highest solubilities in polystyrene were obtained with trioctylphosphine co-ligands. All beads had overall quantum yields in excess of 80% as dried powders and lifetimes well beyond 600 µs. Core-shell particles were devised for the conjugation to model proteins (Avidine, Neutravidine). Their applicability was tested in biotinylated titer plates using time gated measurements and a Lateral Flow Assay as practical examples.