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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]

• 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]

Abstract The author developed the di(3-trifluoromethylphenyl)[3-(dioctylphosphinyl)propyl]phosphine oxide (DPDO-mCF 3) ligand in order to prepare Eu(III) complexes with high photoluminescence intensity and solubility. By coordinating the DPDO-mCF 3 ligand to Eu(III), photoluminescence intensities were increased to 6.4 and 4.3 times those of tris(4,4,5,5,6,6,6-heptafluoro-1-(2-naphthyl)-1,3-hexanedionato)europium(III) (Eu(III)(hfnh) 3 ; 4) and tris(6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionato)europium(III) (Eu(III)(fod) 3 ; 5), respectively. Coordination of the DPDO-mCF 3 ligand also increased the asymmetry ratio, total photoluminescence quantum yield (Φ TOT), and absorbance of Eu(III) complexes. Φ TOT of Eu(III)(hfnh) 3 (DPDO-mCF 3) (1) was 0.60 in ethyl acetate at a concentration of 1 × 10−3 mol/L and 0.82 in the solid state. In addition, Φ TOT of Eu(III)(fod) 3 (DPDO-mCF 3) (2) is 0.39 in ethyl acetate at a concentration of 1 × 10−3 mol/L and 0.56 in the solid state. Solid-state quantum yields were larger than solution-state quantum yields across a wide wavelength region. Furthermore, the solubility of 2 in 2,3-dihydrodecafluoropentane (54 μmol/g) was far higher than that of 5 (7.2 μmol/g). DPDO-mCF 3 is thus an innovative ligand for Eu(III) complexes, and Eu(III) complexes bearing a DPDO-mCF 3 ligand are promising candidates for many applications, including LED devices, secure media, and sensing devices. Graphical abstract Image 1 Highlights • DPDO-mCF 3 ligand notably increases the quantum yields of Eu(III) complexes. • DPDO-mCF 3 ligand notably increases solubilities of Eu(III) complexes. • DPDO-mCF 3 is the innovative ligand for Eu(III) complexes. • The quantum yield of Eu(III)(hfnh) 3 (DPDO-mCF 3) 1 is 0.6 in ethyl acetate. [ABSTRACT FROM AUTHOR]

Abstract: A europium(III) [Eu(III)] complex and a viologen derivative were covalently immobilized on a porous titanium(IV) dioxide (TiO2) electrode by the interaction of carboxyl and phosphate groups with the surface, demonstrating electrochemically induced photoluminescence and coloration switching. The modulation of emission and coloration using the functional Eu(III)‐viologen modified TiO2 electrode was achieved by an electrochemical reaction between TiO2 and the viologen derivative. Luminescence control was induced via electron and energy transfer from the Eu(III) complex to TiO2 and the linked viologen derivative. The dual functional electrode showed a high on‐off emission contrast (81:1), short response time (off: 2.5 s at −0.8 V, on: 5 s at 0 V), and high stability (over 150 cycles) for both emission and coloration control. [ABSTRACT FROM AUTHOR]

Several Eu(III) complexes with two phosphine oxide ligands and three β-diketonate ligands were prepared and their properties were investigated to realize strong photoluminescence and highly soluble Eu(III) complexes. Comparison of photoluminescence properties of Eu(III) (tfnb) 3 (TPPO) 2 ( 5 ) (tfnb = 4,​4,​4-​trifluoro-​1-​(2-​naphthyl)​-​1,​3-​butanedionato and TPPO = triphenyl phosphine oxide), Eu(III)(tfpb) 3 (TPPO) 2 ( 6 ) (tfpb = 4,4,4-trifluoro-1-phenyl-1,3-butanedionato), Eu(III) (hfnh) 3 (TPPO) 2 ( 8 ) (hfnh = 4,4,5,5,6,6,6-heptafluoro-1-(2-naphthyl)-1,3-hexanedionato) and Eu(III)(tfdh) 3 (TPPO) 2 ( 9 ) (tfdh = 6,6,6-trifluoro-2,2-dimethyl-3,5-hexanedionato), which have the same phosphine oxide, reveals that photoluminescence intensities are in the descending order 8 , 5 , 6 , 9 . “hfnh” and “tfnb” are found to be preferable for molecular structures of β-diketonates. Next, effects of molecular structures of phosphine oxide- ligands on photoluminescence intensities of Eu(III) complexes were investigated. Comparison of photoluminescence spectra of Eu(III) (hfnh) 3 (TBPO) 2 ( 7 ) (TBPO = tributyl phosphine oxide), Eu(III) (hfnh) 3 (TPPO) 2 ( 8 ) and Eu(III) (hfnh) 3 (TPPO)(TBPO) ( 12 ), which have the same β-diketonate (hfnh), reveals that photoluminescence intensities are in the descending order 12 , 7 , 8 . Likewise, comparison of photoluminescence spectra of Eu(III) (tfnb) 3 (TBPO) 2 ( 3 ), Eu(III) (tfnb) 3 (TPPO) 2 ( 5 ) and Eu(III) (tfnb) 3 (TPPO)(TOPO) ( 11 ), which have the same β-diketonate (tfnb), reveals that photoluminescence intensities are in the descending order 11 , 5 , 3 . On the other hand, solubilities of Eu(III) (tfnb) 3 (TPPO)(TBPO) ( 11 ) and Eu(III) (hfnh) 3 (TPPO)(TBPO) ( 12 ) with two different phosphine oxides in 2,3-dihydrodecafluoropentane are much larger than those of other complexes. These results indicate that the optimum β-diketonate is “hfnh” and coordination of two different phosphine oxides with one Eu(III) ion has a remarkable effect in enlarging both photoluminescence intensity and solubility of Eu(III) complexes. Eu(III) complex 12 satisfies these conditions and quantum yield is very high (= 0.6). It is a promising candidate for many applications by virtue of its strong photoluminescence and high solubility. [ABSTRACT FROM AUTHOR]

A novel adenine (Ad) fluorescence probe (Eu III -dtpa-bis(guanine)) was designed and synthesized by improving experimental method based on the Eu(III) complex and dtpa-bis(guanine) ligand. The dtpa-bis(guanine) ligand was first synthesized by the acylation action between dtpaa and guanine (Gu), and the corresponding Eu(III) complex was successfully prepared through heat-refluxing method with dtpa-bis(guanine) ligand. As a novel fluorescence probe, the Eu III -dtpa-bis(guanine) complex can detect adenine (Ad) with characteristics of strong targeting, high specificity and high recognition ability. The detection mechanism of the adenine (Ad) using this probe in buffer solution was studied by ultraviolet-visible (UV–vis) and fluorescence spectroscopy. When the Eu III -dtpa-bis(guanine) was introduced to the adenine (Ad) solution, the fluorescence emission intensity was significantly enhanced. However, adding other bases such as guanine (Gu), xanthine (Xa), hypoxanthine (Hy) and uric acid (Ur) with similar composition and structure to that of adenine (Ad) to the Eu III -dtpa-bis(guanine) solution, the fluorescence emission intensities are nearly invariable. Meanwhile, the interference of guanine (Gu), xanthine (Xa), hypoxanthine (Hy) and uric acid (Ur) on the detection of the adenine using Eu III -dtpa-bis(guanine) probe was also studied. It was found that presence of these bases does not affect the detection of adenine (Ad). A linear response of fluorescence emission intensities of Eu III -dtpa-bis(guanine) at 570 nm as a function of adenine (Ad) concentration in the range of 0.00–5.00 × 10 − 5 mol L − 1 was observed. The detection limit is about 4.70 × 10 − 7 mol L − 1 . [ABSTRACT FROM AUTHOR]

A novel Eu(III) complex, [Eu(L)2(H2O)4]·(NO3)·(H2O)4 (1) (H2L = 4-imidazolecarboxaldehyde-pyridine-2-carbohydrazide), was synthesized. Its structure has been characterized by elemental analysis, IR, and X-ray single crystal diffraction analysis. Complex 1 is of orthorhombic, space group Fdd2 with a = 29.471(6) A˚, b = 10.287(2) A˚, c = 24.340(5) A˚, V = 7379(3) A˚3, Z = 8, Mr = 902.58, Dc = 1.625 μg·m-3, μ = 1.789 mm-1, F(000) = 3656, GOOF = 1.099, the final R = 0.0517, ωR = 0.1292 for 3043 observed reflections with I > 2σ(I). The A³ coupling reaction has been investigated using the complex 1 as catalyst. The luminescent spectrum of the complex 1 gives two weak peaks (448 nm and 491 nm) and two strong peaks (596 nm and 620 nm) from excitation at 279 nm. [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]

The paper reports the preparation of two photoluminescent polymer composites by embedding two newly prepared Tb(III) and Eu(III) complexes into poly(4-styrenesulfonic acid) matrices using maleimide as ligand. In the first step, the photoluminescent complexes were prepared at 1:3 metal-to-ligand ratio. Prior to the embedment into the polymer matrix the complexes were investigated by chemical and thermal analysis, FT-IR, powder X-ray diffraction and fluorescence spectroscopy. The prepared composites preserve the photoluminescent properties of the complexes and provide them with long-term stability. Thin films of the composites were spin-coated on glass slides and investigated by SEM and AFM techniques. The remarkable photoluminescent properties of the composites prepared in bulk or deposited in thin films on various substrates recommend them for applications in optical devices as photonic conversion mediums. [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]

Abstract: Luminescent properties of two heteroleptic dibenzoylmethanate europium(III) complexes with 1,3-bis(5-pyridin-2-yl-1,2,4-triazol-3-yl)propane (H2L1) and 1,4-bis(5-pyridin-2-yl-1,2,4-triazol-3-yl)butane (H2L2) as ancillary ligands are described. The two double-layer-type electroluminescent cells with the structures: (1) ITO/NPB(40nm)/Eu(DBM)2HL1 (40nm)/LiF (1nm)/Al (100nm) and (2) ITO/NPB(40nm)/Eu(DBM)2HL2 (40nm)/LiF (1nm)/Al (100nm) emit red light originating from the europium complexes. The device 2 gives the maximum brightness of 455cd/m2 at 19.2V. [Copyright &y& Elsevier]

The report represents the comparative analysis of luminescent properties of Eu(III) complex in colloids of silica-coated and layer-by-layer-fabricated nanoparticles. The diverse morphologies of these nanoparticles greatly affect their photophysical properties. The interfacial binding with d-ions exemplified by Cu(II) and the contributions of the ion exchange and energy transfer processes between Eu(III) ions confined within polymeric coating and Cu(II) ions at the interface of nanoparticles also depend on their morphology. The silica coating of Eu(III) complex does not prevent it from the efficient ion displacement by the interfacial Cu(II) ions, which results in the irreversible quenching of Eu(III)-centered luminescence. The lack of the ion exchange and the predominant energy transfer between Eu(III) ions in the core and interfacial Cu(II) ions are revealed in the colloids of Eu(III) complex reprecipitated from organic to aqueous solution and coated by the layer-by-layer-fabricated polyelectrolyte multilayer. The obtained results represent the synthetic route of the insertion of Cu(II) ions into the polyelectrolyte multilayer fabricated onto Eu(III) complex. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we synthesize a novel diamine ligand of DIQ-Et and its corresponding Eu(III) complex of Eu(TTA)3DIQ-Et, where DIQ-Et=N-ethyl-10H-dipyrido-[f,h]-indolo-[3,2-b]-quinoxaline, and TTA=2-thenoyltrifluoroacetonate. The UV–vis absorption, photoluminescence, low temperature phosphorescence, energy transfer mechanism, and excited state lifetime of Eu(TTA)3DIQ-Et are investigated in detail. Data suggest that the emission of Eu(TTA)3DIQ-Et is quenchable by molecular oxygen due to the back-energy transfer process. By doping Eu(TTA)3DIQ-Et into a polymer matrix of poly(vinylpyrrolidone) (PVP), oxygen sensing performance of the resulted nanofibers is investigated. Finally, the 0.7wt% doped sample exhibits a linear response toward molecular oxygen, with a sensitivity of 2.4 and response/recovery time of 12s/16s. [Copyright &y& Elsevier]

Abstract: The luminescent colloids have been synthesized through the layer-by-layer assembly of poly(sodium 4-styrenesulfonate) (PSS) and polyethyleneimine (PEI) onto the luminescent core. The latter has been obtained by the reprecipitation of complex Eu[(TTA)3 1] (where TTA− and 1 are thenoyltrifluoroacetonate and 2-(5-chlorophenyl-2-hydroxy)-2-phenylethenyl-bis-(2-methoxyphenyl)phosphine oxide, respectively) from organic solvent to aqueous solution. The variation of Eu(III) complexes indicates the role of the complex core in the development of such core–shell colloids. Complex Eu[(TTA)3 1] is most convenient precursor of Eu-doped luminescent nanocomposites. The fluorometric measurements at each step of the layer-by-layer polyelectrolyte assembly onto Eu[(TTA)3 1] core, at various pHs and additives reveal the quenching of Eu-centered luminescence as a result of the interfacial interaction of the core and the dye. The AFM images and electrochemical behavior of PSS–(PEI–PSS) n –Eu[(TTA)3 1] colloids deposited on the surface indicate the stability of the polyelectrolyte multilayer in the dried state. [Copyright &y& Elsevier]

Abstract: The preparation and incorporation in silica gels of a novel europium complex, [Eu(ntac)3][pphendcn] containing 4,4,4-trifluoro-1-(naphthalene-2-yl) butan-1,3-dione (Hntac) and pyrazino[2,3-f][1,10-phenathroline-2,3-dicarbonitrile (pphendcn) is demonstrated. An effective energy transfer from the organic ligands to the Eu(III) ions leads to a strong f–f luminescence even at low activator concentrations, n Eu/n Si ≈1×10−5. The new amorphous materials are characterized by UV/Vis reflectance and transmission spectroscopy, luminescence/excitation spectroscopy, X-ray diffraction, elemental analysis, IR spectroscopy, DTA/TG and NMR. The optical properties of gels with a different Eu(III) doping are discussed. The stability of the europium complex in the silica matrix during time (up to 4months) and after heating is discussed. The Eu(III) spectra–structure correlation is used to characterize the site symmetry of the activator. [Copyright &y& Elsevier]

Abstract: In this paper, we synthesize a novel diamine ligand of PIP and its corresponding Eu(III) complex of Eu(DBM)3PIP, where PIP=2-phenyl-1H-imidazo[4,5-f][1,10]phenanthroline, and DBM=1,3-diphenyl-propane-1,3-dione. The UV–Vis absorption spectra, low temperature phosphorescence spectra, energy transfer mechanism, excited state lifetime of Eu(DBM)3PIP, as well as its photoluminescence spectra, are investigated in detail. Data suggest that the emission of Eu(DBM)3PIP is quenchable by molecular oxygen due to the back-energy transfer process. By doping Eu(DBM)3PIP into a polymer matrix of poly(vinylpyrrolidone) (PVP), the oxygen sensing performance of the resulted nanofibrous membrane is investigated. Finally, the 0.6wt% doped sample exhibits a linear response towards molecular oxygen, with a sensitivity of 3.5 and response/recovery time of 15s/24s. [Copyright &y& Elsevier]

The paper proposes novel molecular designs for rare-earth complexes involving the introduction of two different phosphine oxide structures into one rare-earth ion. These designs are effective for improving solubility and emission intensity. Additionally, the complexes are indispensable for realizing high performances in LEDs and security media. The thermodynamic properties of Eu(III) complexes are correlated with the solubility. Correlations between coordination structures and emission intensity were explained by NMR analysis. The luminous flux of red LED devices with Eu(III) complexes is very high (20 mA, 870 m lumen). A new white LED has its largest spectra intensity in the red region and a human look much more vividly under this light. [ABSTRACT FROM AUTHOR]

Abstract: The core-shell structured luminomagnetic microsphere composed of a Fe3O4 magnetic core and a continuous SiO2 nanoshell doped with Eu(DBM)3·2H2O fluorescent molecules was fabricated by a modified Stöber method combined with a layer-by-layer assembly technique. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), confocal microscopy, photoluminescence (PL), and superconducting quantum interface device (SQUID) were employed to characterize the Fe3O4@SiO2@Eu(DBM)3·2H2O/SiO2 microspheres. The experimental results show that the microshpere has a typical diameter of ca. 500nm consisting of the magnetic core with about 340nm in diameter and silica shell doped with europium complex with an average thickness of about 80nm. It possesses magnetism with a saturation magnetization of 25.84emu/g and negligible coercivity and remanence at room temperature and exhibits strong red emission peak originating from electric-dipole transition 5D0 → 7F2 (611nm) of Eu3+ ions. The luminomagnetic microspheres can be uptaken by HeLa cells and there is no adverse cell reaction. These results suggest that the luminomagnetic microspheres with magnetic resonance response and fluorescence probe property may be useful in biomedical imaging and diagnostic applications. [Copyright &y& Elsevier]

Abstract: Two new multinuclear europium(III) complexes, [Eu(AFTFBD)3]2(1,4-bmb) and [Eu(AFTFBD)3]3(tmb) were designed and synthesized, where HAFTFBD was 2-acetylfluorene-4,4,4-trifluorobutane-1,3-dione, 1,4-bmb was 1,4-bis[2-(2′-pyridyl)benzimidazolyl]benzene and tmb was 1,3,5-tris[2-(2′-pyridyl)benzimidazolyl]benzene. The complexes were characterized by IR, UV–visible, photoluminescence (PL) spectroscopy and thermogravimetric analysis (TGA). The complexes emit the characteristic red luminescence of Eu3+ ion due to the 5 D 0–7 FJ (J =0–4) transitions under 395nm-light excitation. Bright red light-emitting diodes were fabricated by coating the selected complex (Eu(AFTFBD)3)3(tmb) onto ∼395nm-emitting InGaN chips, and the LEDs show appropriate CIE chromaticity coordinates in red area. All these results suggest that the Eu(III) complexes are promising candidates as red component for application in fabrication of near UV-based white light-emitting diodes. [Copyright &y& Elsevier]

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]

Abstract: Anionic Europium(III) complexes EuL1, EuL2 and EuL3 (L1=tris (dipicolinate), L2=diethylenetriaminepentaacetate, L3=disulfonated bathophenanthroline tris(dibenzoylmethanate) were intercalated in Zn2Al(OH)6Cl, nH2O and Zn4Al(OH)10Cl, nH2O layered double hydroxides (LDHs). Intercalation was confirmed by X-ray diffraction, vibration spectroscopy and photoluminescence measurements, using Eu(III) as a local structural probe. Information on host–guest interactions in the hybrid materials were deduced by analyzing the intensity parameter Ω2, the energy position of the 5D0–7F0 transition and the emission decay profile of the prominent hypersensitive red 5D0–7F2 emission. [Copyright &y& Elsevier]

• 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]

[Display omitted] Eu(III) host-guest complex: A host-guest complex 1 was controllably self-assembled using hydrogen bonding directed encapsulation strategy. In this host-guest inclusion systems, a reversible structure transformation between two complexes can be controlled exactly via sequentially changing different guest molecules (hydroxides and solvated lanthanide ions). In this interconversion process, the host molecular conformation motion, EuIII–centered emission enhancement and fluorescence imaging behavior were also observed. • Eu(III)-based host-guest complex is self-assembled via multiple hydrogen bonds. • The host conformation motion and emission enhancement behavior are also observed. • Emissive complex could be used as an imaging regent in living cell potentially. Host-guest interaction is widely employed as a powerful tool to create supramolecular assembles with multicomponent units. In this work, an emissive quinoline-based tripodal acceptor L1 with tunable syn and anti -conformers was synthesized and used as host. Upon binding with guest species, Eu(III)-based host–guest complex 1 (L1 ⊃ [Eu(NO 3) 3 (H 2 O)(CH 3 OH) 2 ]) was constructed via host–guest interaction driven by multiple hydrogen bonds. Furthermore, in this complex, host conformation motion and Eu(III)–centered emission enhancement behavior are also observed by X-ray single crystal diffraction and fluorescence spectrometer. Theoretically, Density Functional Theory (DFT) calculations revealed that the anti and syn -conformations are stabilized by complexation of solvated lanthanide ions within cavity of tripodal host L1 , respectively. The calculations were in good agreement with the experimental data. Moreover, emissive host–guest complex 1 could be used as an imaging regent in living cell potentially. [ABSTRACT FROM AUTHOR]

Abstract: A β-diketone, 4-imidazol-4,4,4-trifluorobutane-1,3-dione (HIDTFBD) and the corresponding europium(III) complex Eu(IDTFBD)3phen were designed and synthesized, where phen was 1,10-phenanthroline. The complex was characterized by IR, UV–visible, thermogravimetric analysis (TGA) and photoluminescence (PL) spectroscopy. Monitored at 610nm, the Eu(III) complex exhibited a strong and wide excitation band between 320 and 420nm due to the formation of a big π-conjugated system in the complex molecule. Under near UV-light excitation, the complex showed strong red emission of Eu3+ ion due to the 5 D 0–7 F J (J =0–4) transitions. The fluorescence lifetime and the luminescence quantum yield were also measured. Finally, a bright red light-emitting diode was fabricated by coating the europium ternary complex onto an ~395nm-emitting InGaN chip, and the LED exhibited appropriate CIE chromaticity coordinates in red area. All these results suggest that the Eu(III) complex is a promising candidate as red component for fabrication of near UV-based white light-emitting diodes. [Copyright &y& Elsevier]

Three novel coumarin Schiff base derivatives and corresponding Eu(III) complexes were designed and synthesized. The aggregation-induced emission (AIE) property of ligands was studied. The fluorescence properties and electrochemical properties of Eu(III) complexes were investigated by comparing different substituent groups. The ion selectivity and ion detection limits of the [EuL2(NO 3) 3 •H 2 O were also studied. The result indicates that all ligands exhibit the AIE property in CH 3 CN/H 2 O solution and emit green fluorescence with the maximum emission wavelength of 552 nm. All complexes show characteristic red fluorescence of Eu(III) and the influence of different substituents on the fluorescence intensity of Eu(III) complexes is ordered: -OCH 3 > -H > -NO 2, and [EuL2(NO 3) 3 •H 2 O exhibits the strongest fluorescence intensity. The density functional theory (DFT) calculations of the ligands indicate that the introduction of electron-donating groups increases the HOMO energy level and the electron cloud density, which enhance the ability to coordinate with Eu(III) and the fluorescence intensity of the corresponding complex. Besides, the electrochemical properties of Eu(III) complexes indicate that the introduction of electron-donating groups increases the energy gaps (Eg) and the conjugation of the complex, which enhances the fluorescence intensity of the complexes. Ion selectivity experiments show that [EuL2(NO 3) 3 •H 2 O has a specific recognition function for F−, and its response limit is between 1.0 × 10−5 mol·L−1 and 2.2 × 10−5 mol·L−1. Based on the above results, all the ligands and Eu(III) complexes have a promising application in optical materials due to the excellent fluorescence properties. In addition, All Eu(III) complexes also have a potential application prospects in the field of fluoride ion detection. Unlabelled Image • Novel coumarin Schiff base ligands and their Eu(III) complexes were synthesized. • The ligands exhibit the AIE property, and emit the green fluorescence. • The electron donor group enhances the fluorescence intensity of the complex. • EuL2(NO 3) 3.H 2 O is selective for F− in the range of 1.0 × 10−5–2.2 × 10−5 mol/L. [ABSTRACT FROM AUTHOR]

An intrinsic Eu(III) luminescence phenomenon of Eu(III) complex was found under near-infrared light (NIRL) excitation of xenon lamp, and the maximum excitation wavelength is about twice the excitation wavelength of its Stokes fluorescence. The NIRL excitation fluorescence was mainly originated from second order diffracted light (SODL) excitation. The Eu(III) complex was consist of Eu(III), Gd(III), 2-trifluoroacetylacetone (TTA) and cetyltrimethylammonium bromide (CTAB). Curcumin (Cur) could notably quench the luminescence intensity of the Eu(III) complex. Based on this, a sensitive method for Cur detection was developed. Under optimum conditions, the decrease extent in the fluorescence intensity at 611 nm exhibited a good linear relationship with the Cur concentration in the range of 2.0 × 10−9 mol/L - 6.0 × 10−8 mol/L under 746 nm excitation, the limit of detection (LOD, S/N = 3) was 5.2 × 10−10 mol/L. While, the linear relationship and the LOD of Stokes fluorescence method (λ ex / λ em = 360/611 nm) were found to be 1.0 × 10−8 mol/L - 6.0 × 10−8 mol/L and 2.6 × 10−9 mol/L, respectively. The former method is superior to the latter one in Cur detection. Both two methods were successfully applied to determine Cur in real samples. The luminescence mechanism of Eu(III) complex under the NIRL excitation and the quenching mechanism of Cur on the Eu(III) fluorescence was also investigated. Image 1 • Luminescence of Eu(III) complex under near-infrared Xe-light excitation was found. • Second order diffracted light excitation dominates in NIRL excitation fluorescence. • NIRL method for Cur detection shows some advantages in sensitivity and linear range. [ABSTRACT FROM AUTHOR]

• Slight difference of diphosphine dioxide-ligands has notable effects on properties. • The half width of 5D 0 → 7F 2 transition of Eu(III) complex 1 is 3 nm in solid state. • Eu(III) complex 1 with i -Pr groups has higher symmetry in ligand fields. • Slight difference of diphosphine dioxide ligand has significant effects on properties. Slight difference of molecular substructures of diphosphine dioxide-ligands has significant effects on properties of Eu(III) complexes. Half width of 5D 0 → 7F 2 transition, life time, and quantum yield of Eu(III) complex 1 with i -propyl group substituted diphosphine dioxide are quite different from those of Eu(III) complexes 2 and 3 with n -butyl group substituted diphosphine dioxide-ligands. Smaller half width and Ratio R in solid state of complex 1 indicate that complex 1 has higher symmetry than others. [ABSTRACT FROM AUTHOR]