Lanthanide complexes based on the quinolinecarboxylate ligand 2-phenyl-4-quinolinecarboxylic acid (PQC), namely, Ln2PQC6 (Ln = La3+, Pr3+, Nd3+, Sm3+ and Eu3+) were synthesized by a convenient solvothermal reaction, and the related crystal structures were determined. These complexes are isostructural and feature a discrete dinuclear moiety, in which solvent molecules act as coligands and the Ln3+ centre exhibits distorted tricapped trigonal prism geometry. By the introduction of the PQC ligand, the europium sample Eu2PQC6 (5) showing intense red emission in the solid state and solution, with both the replaceable coordination environment and potential hydrogen-bonding-accepting site, can be explored as a luminescent probe for sensing various anions. Among the tested ions (F−, Cl−, Br−, I−, NO3−, ClO4−, SCN−, HCO3−, HSO4− and H2PO4−), HSO4− and H2PO4− possess a strong response in the Eu3+ emitting behaviour leading to a unique quenching with a low detection limit of 15.3 and 8.3 nM, respectively, and a quick response time of less than 30 s. The different recognition mechanisms for two anions, including O–H⋯N hydrogen bonding and metal coordination modes have been proposed, which are supported by UV-vis, fluorescence spectroscopy, nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) measurements. In addition, density functional theory (DFT) calculations were carried out to verify the two recognition mechanisms of Eu2PQC6 in depth. As an extended research, Eu2PQC6 interaction with the nucleoside phosphates adenosine triphosphate (ATP), adenosine diphosphate (ADP) and adenosine monophosphate (AMP) in mixed aqueous solution was investigated, which can act as a special luminescent sensor for all three phosphates. The strong quenching by ADP (99.5%), has been ascribed to the strong bonding affinity (logKa = 5.99) based on electrostatic attractions and steric effects.

Transparent AlON ceramic was pressurelessly sintered from powder synthesized by direct nitridation of Al–Al2O3 starting mixtures. TG, SEM and XRD analyses were conducted to investigate the detail procedure of direct nitridation. The Al spheres were dispersed by submicron Al2O3, then nitrided and reacted with Al2O3 to form AlON. The particle size of AlON is about 10–30 μm with irregular morphology. With the aid of ball milling and sintering additives, 2 mm thick AlON ceramic with in-line transmittance of 80.6% at 1100 nm and above 77.1% at 400 nm was obtained successfully, demonstrating that the direct nitridation method is another promising approach for the preparation of AlON ceramics with high transparency.

AlON:1.6 mol.%Er3+, x mol.%Yb3+ (x=0, 2.6, 3.1, 3.6, 4.1, 4.6) phosphors were synthesized successfully by aluminothermic reduction and nitridation (ATRN) method and characterized by X-ray diffraction (XRD), scanning electron microscopy (FESEM) and upconversion photoluminescence (UCPL) emission spectra. Under the excitation of diode laser 980 nm, the green (556 nm) and red (655 nm) upconverted emissions were observed, attributed to the 4S3/2→4I15/2 and 4F9/2→4I15/2 transition of Er3+ respectively. The emission intensity increased with increasing Yb3+ concentration due to the energy transfer (ET) between Yb3+ and Er3+. The upconverted emission reached the highest as x=3.6, and was pump-power dependent involving a two-photon process.Emission spectra of AlON:1.6Er3+, xYb3+ samples (x=0 mol.%, 2.6 mol.%, 3.1 mol.% and 3.6 mol.%)

Eu2PQC6 has been developed to detect Al3+ by monitoring the quenching of the europium-based emission, with the lowest detection limit of ∼32 pM and the quantitative detection range to 150 μM. Eu2PQC6 is the first ever example that the europium(III) complex serves as an Al3+ fluorescent sensor based on “competition-displacement” mode.

A series of novel one-dimensional (1D) lanthanide coordination polymers, [Ln(pqc)(Hpqc)(NO3)2]n (Ln = Sm (1), Eu (2), Gd (3), Tb (4), Dy (5), Ho (6), Er (7), Tm (8), Yb (9), or Lu (10); Hpqc = 2-phenyl-4-quinolinecarboxylic acid), have been synthesized via solvothermal reaction at low temperature and then characterized by single-crystal X-ray diffraction. Polymers 1–10 are isostructural and feature a 1D chain based on binuclear units in which Ln3+ polyhedra are interconnected by bridging Hpqc ligands and terminal nitrates. The infinite chains are further extended to a three-dimensional supramolecular framework through π···π stacking and hydrogen bonding interactions. This series affords an opportunity to study the lanthanide contraction effect, demonstrating that the sum of Ln–O distances proportional to this contraction follow a quadratic decay as a function of the number n of f electrons. The photoluminescence spectra show that these complexes are highly sensitized by Hpqc and exhibit characteristic Ln3+ (Sm (1), Eu (2), Tb (4), Er (7), and Yb (9)) and ligand centered (Dy (5), Ho (6), Tm (8), and Lu (10)) luminescence in both visible and near-infrared (NIR) regions. The magnetic properties of 4–7 have also been investigated.

The red phosphor Na5Eu(WO4)4 activated with trivalent M3+ (M3+ = Bi3+, Sm3+) ions were prepared through the solid state reaction technique. The properties of structure, morphology, photoluminescence were characterized systematically. The lattice parameters were refined by Rietveld method. The emission spectra, excitation spectra, and decay curves were employed to study the luminescent behaviors. Both of Bi3+ and Sm3+ doping could increase the red-emitting intensity and corresponding quantum efficiency (QE) of Na5Eu(WO4)4 host. Furthermore, the color rendering index of the commercial yellow phosphor YAG:Ce3+ was increased from 44.5 to 50.8 and 50.2 by mixed with Na5Eu0.8Bi0.2(WO4)4 and Na5Eu0.96Sm0.04(WO4)4 phosphors under 465 nm excitation, respectively. The CIE chromaticity coordinates of these phosphors are close to the standard value for red. Herein, the present materials are promising candidates as red phosphors for white light emitting diodes with near-UV/blue GaN-based chips.Highlights► Na5Eu(WO4)4:(Bi3+, Sm3+) phosphors were synthesized by solid-state reaction method. ► Bright red light can be observed from Na5Eu(WO4)4:(Bi3+, Sm3+) under 395 nm or 465 nm excitation. ► The crystal structure and parameters of the samples were refined by the Rietveld method. ► Na5Eu0.8Bi0.2(WO4)4 and Na5Eu0.96Sm0.04(WO4)4 phosphors bear with 59.6% and 53.3% QE.

A series of Na5La1−xEux(WO4)4 (x=0, 0.05, 0.1, 0.2, 0.3, 0.4, 0.6, 0.8, 1.0) phosphors have been synthesized successfully by a solid-state reaction technique and characterized by X-ray diffraction, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and Rietveld refinement. The photoluminescent properties have also been systematically investigated under the near-ultraviolet light. High concentration of doped Eu3+ enhanced the UV absorption and consequently red emission without concentration quenching. The Na5Eu(WO4)4 phosphor was observed a strong red emission under 395 nm excitation, bearing with 47% quantum efficiency and the CIE chromaticity coordinates (x=0.67, y=0.33) being close to the National Television Standard Committee (NTSC) standard values. The primary studies indicate that Na5Eu(WO4)4 is a promising candidate as the red phosphor for white light-emitting diodes (LEDs).Highlights► Novel red emitting phosphors Na5La1−xEux(WO4)4 were synthesized. ► The phosphors were excited near 395 nm and showed no concentration quenching. ► The crystal structure and parameters were refined using the Rietveld method. ► The calculated quantum efficiency of Na5Eu(WO4)4 specimen is around 47%.

Two coordination polymers, [Zn(PPA)2(H2O)2]n (1) and [Cd(PPA)2]n (2) (HPPA = 3-pyridinepropionic acid) have been hydrothermally synthesized. Both of 1 and 2 crystallize in P-1 space group. Zn(II) centers in 1 are extended by PPA ligands to form the 1D chains, which are consolidated by hydrogen bonding to construct a 3D supramolecular network. The structure of 2 represents a rare binodal (3,6)-connected 2D layer with kgd topology. The luminescent properties of 1 and 2 in the solid state are discussed.Two coordination polymers, [Zn(PPA)2(H2O)2]n (1) and [Cd(PPA)2]n (2) (HPPA = 3-pyridinepropionic acid) have been hydrothermally synthesized. Compound 1 owns 1D chain structure, while the structure of 2 represents a rare binodal (3,6)-connected 2D layer with kgd topology. The luminescent properties of 1 and 2 in the solid state are consequently different.Highlights► Two polymers of seldom-adopted 3-pyridinepropionate (PPA) were obtained. ► [Cd(PPA)2]n (2) with a rare kgd topology is first structurally characterized. ► [Zn(PPA)2(H2O)2]n (1) and 2 demonstrate a route to enhanced luminescence.

Lanthanide complexes based on the quinolinecarboxylate ligand 2-phenyl-4-quinolinecarboxylic acid (PQC), namely, Ln2PQC6 (Ln = La3+, Pr3+, Nd3+, Sm3+ and Eu3+) were synthesized by a convenient solvothermal reaction, and the related crystal structures were determined. These complexes are isostructural and feature a discrete dinuclear moiety, in which solvent molecules act as coligands and the Ln3+ centre exhibits distorted tricapped trigonal prism geometry. By the introduction of the PQC ligand, the europium sample Eu2PQC6 (5) showing intense red emission in the solid state and solution, with both the replaceable coordination environment and potential hydrogen-bonding-accepting site, can be explored as a luminescent probe for sensing various anions. Among the tested ions (F−, Cl−, Br−, I−, NO3−, ClO4−, SCN−, HCO3−, HSO4− and H2PO4−), HSO4− and H2PO4− possess a strong response in the Eu3+ emitting behaviour leading to a unique quenching with a low detection limit of 15.3 and 8.3 nM, respectively, and a quick response time of less than 30 s. The different recognition mechanisms for two anions, including O–H⋯N hydrogen bonding and metal coordination modes have been proposed, which are supported by UV-vis, fluorescence spectroscopy, nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) measurements. In addition, density functional theory (DFT) calculations were carried out to verify the two recognition mechanisms of Eu2PQC6 in depth. As an extended research, Eu2PQC6 interaction with the nucleoside phosphates adenosine triphosphate (ATP), adenosine diphosphate (ADP) and adenosine monophosphate (AMP) in mixed aqueous solution was investigated, which can act as a special luminescent sensor for all three phosphates. The strong quenching by ADP (99.5%), has been ascribed to the strong bonding affinity (logKa = 5.99) based on electrostatic attractions and steric effects.