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• Enlarged the repertory of circularly polarized luminescence (CPL) materials. • Strategy of structural modification for CPL materials was successfully achieved. • Increased polarity of substituent in ligand was found to enhance of CPL properties. • Chiral Schiff-base and achiral β -diketone had dominated effect on CPL and PL respectively. • The three complexes exhibited rapid recognition to Co(II) ion. Circularly polarized luminescence (CPL) has received much attention in optical displays, information storage, and biological probes. Designing effective strategy to improve the CPL activities is significant for complex materials. Structural modification is a rational way which is seldom reported. In this work, three chiral binuclear Eu(III) complexes coordinated with different chiral Schiff base ligands were designed and synthesized. CPL performances of these Eu(III) complexes were substantially improved by polarity of substituents at the chiral carbon sites of the ligands, leading to a five-fold increase in the luminescence dissymmetry factor (g lum). Additionally, three complexes exhibited similar luminescence properties with the characteristic peaks of Eu(III) ion, which can be rapidly quenched by Co(II) ion, allowing their further applications in anti-counterfeiting and sensors. Therefore, this work not only uncovers the relationship between the substituents of chiral ligand and the corresponding CPL properties of Eu(III) complexes to some extent, but also creates opportunities for design and synthesis of Eu(III) complexes with excellent CPL activity. Three substituents with intensified polarity were turned at chiral sites of the Schiff-base ligands, which enhance CPL activity of chiral binuclear Eu(III) complex, that the g lum of the complex enhanced 5 times and the rapid recognition to Co(II) were applied in anti-counterfeiting and sensors. [Display omitted] [ABSTRACT FROM AUTHOR]

New Tb(III) and Eu(III) complexes based on aryl-2,2′-bipyridine ligands with a cyclic DO3A chelating unit appended in the alpha position of the bipyridine core were synthesized. The photophysical properties of these complexes were compared with those of complexes of ligands with identical aryl-2,2′-bipyridine chromophores, but with an acyclic DTTA residue as an additional chelating site in the alpha position of the bipyridine core. The nature of the polyaminocarboxylic acid fragments was found to have a significant influence on the luminescence. For some of the Eu(III) complexes, upon the transition from acyclic DTTA- to the cyclic DO3A-appended ligands, a noticeable increase in the intensity of Eu(III) luminescence was observed, with an increase in the quantum yield of up to 2.55 times. In contrast, for most of the Tb(III) complexes, a similar transition resulted in a noticeable decrease in the luminescence intensity of the Tb(III) cation. [ABSTRACT FROM AUTHOR]

Linked to Alzheimer's disease (AD), amyloids and tau-protein are known to contain a large number of cysteine (Cys) residues. In addition, certain levels of some common biogenic thiols (cysteine (Cys), homocysteine (Hcy), glutathione (GSH), etc.) in biological fluids are closely related to AD as well as other diseases. Therefore, probes with a selective interaction with the above-mentioned thiols can be used for the monitoring and visualizing changes of (bio)thiols in the biological fluids as well as in the brain of animal models of Alzheimer's disease. In this study, new Eu(III), Tb(III), Gd(III) and Sm(III) complexes of 2,2′-bipyridine ligands containing TEMPO fragments as receptor units for (bio)thiols are reported. The presence of free radical fragments of the ligand in the complexes was proved by using the electronic paramagnetic resonance (EPR) method. Among all the complexes, the Eu(III) complex turned out to be the most promising one as luminescence- and spin-probe for the detection of biogenic thiols. The EPR and fluorescent titration methods showed the interaction of the resulting complex with free Cys and GSH in solution. To study the practical applicability of the probes for the monitoring of AD in-vivo, by using the above-mentioned Eu(III)-based probe, the staining of the brain of mice with amyloidosis and Vero cell cultures supplemented with the cysteine-enriched medium was studied as well as the fluorescence titration of Bovine Serum Albumin, BSA (as the model for the thiol moieties containing protein), was carried out. Based on the results of fluorescence titration, the formation of a non-covalent inclusion complex between the above-mentioned Eu(III) complex and BSA was suggested. [ABSTRACT FROM AUTHOR]

The terpyridine Eu(III) complex with an alkyl-substituted phenyl-capped aniline dimer shows ternary electrofluorochromic behavior under different potentials. [Display omitted] • Terpyridine Eu(III) complexes with multiple redox states. • The resulted complex displays an unique electrofluorochromic behavior. • With ternary conversion among orange, dark-blue and pale-yellow colors. • And red, deep-blue and greenish-blue PL emissions. Three new terpyridine Eu(III) complexes, [(L 1-3)Eu(HFA) 3 ] (where L 1 = 4′-phenyl-2,2′:6′,2″-terpyridine, L 2 = 4′-{[ p -(N-butyl-N-phenyl)amino]-phenyl}-2,2′:6′,2″-terpyridine}, L 3 = 4′-{ p -[ p -(N,N′-dibutyl-N′-phenyl)-phenyldiamino]-phenyl}-2,2′:6′,2″-terpyridine, and HFA = hexafluoroacetylacetone), have been successfully synthesized and characterized by UV–vis absorption spectrum, FTIR, MALDI-TOF MS and elemental analysis. The X-ray crystallography of complex [(L 2)Eu(HFA) 3 ] shows that the europium(III) ion is nine-coordinated with N3O6 donors in normal ranges. Owing to the antenna effect, complex [(L 1)Eu(HFA) 3 ] (Ф = 0.44) possesses ca. 3 times enhancement of the metal-centered red emission intensity compared to that of precursor Eu(HFA) 3 (Ф = 0.16). The most interesting is that complex [(L 3)Eu(HFA) 3 ] displays an unique electrofluorochromic behavior with the ternary absorption (orange/dark-blue/pale-yellow) and PL emission (red/deep-blue/greenish-blue) conversions, in which the ICT, cation radicals-related and Eu(III)-centered electronic transitions are involved. [ABSTRACT FROM AUTHOR]

Recognition and discrimination of citrate and its isomer, isocitrate, are important but challenging for monitoring the energy metabolism process in clinical conditions, since they have similar chemical and physical properties. In this work, we constructed a luminescent supramolecular vesicle with novel amphiphilic Eu3+ complex (EuL + ). Highly selective detection and discrimination of citrate and isocitrate at micromolar analyte concentration were realized via cooperative interaction between luminescent vesicular interface and the isomers, representing the most sensitive sensing system for the isomers. Interestingly, EuL + vesicles showed different degrees of enhancement in luminescence intensity in the presence of citrate (5.1-fold) or isocitrate (1.7-fold) due to their imparity in the coordination with EuL + . Moreover, EuL + vesicles displayed high selectivity towards citrate even in the presence of other carboxylates and anions. Based on this, the as-prepared luminescent vesicles were successfully employed to track the conversion process between citrate and isocitrate. Recognition and discrimination of citrate and its isomer, isocitrate, are important but challenging for monitoring the energy metabolism process in clinical conditions, since they have similar chemical and physical properties. In this work, we constructed a luminescent supramolecular vesicle with novel amphiphilic Eu3+ complex (EuL + ). Highly selective detection and discrimination of citrate and isocitrate at micromolar analyte concentration were realized via cooperative interaction between luminescent vesicular interface and the isomers, representing the most sensitive sensing system for the isomers. Interestingly, EuL + vesicles showed different degrees of enhancement in luminescence intensity in the presence of citrate (5.1-fold) or isocitrate (1.7-fold) due to their imparity in the coordination with EuL + . Moreover, EuL + vesicles displayed high selectivity towards citrate even in the presence of other carboxylates and anions. Based on this, the as-prepared luminescent vesicles were successfully employed to track the conversion process between citrate and isocitrate. [Display omitted] • A novel amphiphilic Eu(III) complex was designed and synthesized. • Spherical vesicles with a highly ordered nano-interface were constructed in aqueous solution. • Detection and discrimination of citrate and isocitrate via cooperative interaction between vesicular interface and isomers. • The luminescent vesicles were successfully employed to track the conversion process between citrate and isocitrate. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fabrication of new optical sensor membranes for anthracene detection in Suez Bay. • Validation of new sensor was achieved through comparison with gas chromatography. • Developed MTP displayed high efficient and direct determination with low D L. • Applicability of MTP has been demonstrated by the recovery and reusability study. A luminescent microtiter plate (MTP) sensor was fabricated using Eu (III) complex with 4,4,4 trifluoro 1-(2-naphthyl) 1,3 butanedione for screening anthracene in seawater samples. The quenching constant (K SV), binding constant (K D), detection (D L) and quantification limits (Q L) were 2.34 ×106 mol−1 L, 8.89 ×105 mol−1 L, 0.049 μmol L−1, and 0.145 μmol L−1, respectively. Eu(TAN) 3 is embedded in a membrane made of polyvinyl chloride to fabricate microtiter plate sensor. Gas chromatography was used to validate Eu(TAN) 3 MTP for accurate and precise anthracene sensing. Effect of matrix, incubation time, temperature, selectivity and sensitivity of the Eu(TAN) 3 MTP toward anthracene was examined. According to obtained results, Eu(TAN) 3 MTP is capable of detecting anthracene quickly and accurately. [ABSTRACT FROM AUTHOR]

Eu(III) complex/polymer composite nanofibers of poly(vinylpyrrolidone) (PVP) and europium complex Eu(N-DIIQ)(TTA) 3 (N-DPIQ = N-ethyl-dipyrido [ f,h ] indolo [ 3,2-b ] quinoxaline, TTA = 2-thenoyltrifluoroacetonate) are prepared by electrospinning. The composite nanofibers are characterized by Scanning Electron Microscope (SEM), Infrared absorption spectra (IR), and luminescence intensity quenching upon various oxygen concentrations. It is observed that the Eu(III) complex/polymer composite nanofibers exhibit a strong oxygen dependent characteristic. The oxygen-sensing properties of the composite nanofibers with different loading levels of Eu(III) complex are compared. • The energy transfer mechanism between ligands and Eu(III) center is studied. • Oxygen-sensing properties of the Eu(III) complex in poly(vinylpyrrolidone) prepared by electrospinning are investigated. • The decrease of emission intensity for Eu(III) complex is caused by the ground state oxygen quenching on antenna ligands. • Composite nanofiber exhibits a sensitivity of 2.43, a short response time of 10 s, and good linearity. [ABSTRACT FROM AUTHOR]

• A Eu(III) complex was covalently grafted to the mesoporous MCM-41 backbone. • The resulting Eu-MCM-41 exhibited a high selectivity and good linearity for Hg(II). • The sensing mechanism was revealed as the fluorescence quenching by Hg(II). Mercury widely spreads in atmosphere, lithosphere, and surface water. Concentrated mercury levels could be harmful for individuals with neurological diseases because of bioaccumulation of mercury within brains and kidneys. Mercury is thus considered to be a very dangerous element by the United States Environmental Protection Agency due to the severe immunotoxic, genotoxic, and neurotoxic effects. Consequently, the detection of mercury ions is an important issue for environment and human health. An easily synthesized Eu(III) complex of Eu(PTA) is covalently grafted to the ordered functionalized mesoporous MCM-41 backbone, hoping to explore a novel fluorescence chemosensor with high sensitivity and selectivity for Hg(II) detection in aqueous solution. Fourier transform IR, Small-angle X-ray diffraction, High-Resolution TEM, Nitrogen adsorption/desorption, UV-vis absorption and emission have been employed to characterize the organically modified mesoporous material. The Eu-MCM-41 based chemosensor exhibits a high selectivity for Hg(II), and has a good linearity within the range of 1–12 µmol/L in aqueous solution, suggesting the possibility for real-time qualitative or quantitative detection of Hg(II), as well as a wide potential application in environmental monitoring. The recognition of Hg(II) in actual samples from different sources has been examined by this chemosensor. Additionally, the sensing mechanism of Eu-MCM-41 based chemosensor towards Hg(II) is also investigated and discussed in detail. [Display omitted] [ABSTRACT FROM AUTHOR]