Highly luminescent mixed-ligand bimetallic lanthanoid(III) complexes for photovoltaic applications

Six new mixed-ligand bimetallic complexes [Eu₂(bz)₄(tta)₂(phen)₂] (1), [Gd₂(bz)₄(tta)₂(phen)₂] (2), [EuTb(bz)₄(tta)₂(phen)₂] (3), [EuGd(bz)₄(tta)₂(phen)₂] (4), [Eu_1,2Gd_0,8(bz)₄(tta)₂(phen)₂] (5) and [Eu_1,6Gd_0,4(bz)₄(tta)₂(phen)₂] (6) have been prepared with the Eu³⁺, Gd³⁺ and Tb³⁺ ions and the benzoate (bz^-), 2-thenoyltrifluoroacetonate (tta^-) and the 1,10-phenanthroline (phen) ligands. The compounds combine highly efficient antennas to obtain highly luminescent complexes to enhance solar cell efficiency. The benzoate ligand has been chosen to take its advantage as a bridging ligand to end up with bimetallic complexes to study the effect of combining two metal ions in the luminescent molecule. The structure of 1 was obtained by single-crystal X-ray diffraction, and 1-6 were found to be isostructural by powder X-ray diffraction analysis. The photophysical properties were studied by the absorbance and emission spectra and emission lifetimes. The magnetic properties of 2 were studied, and we found intramolecular antiferromagnetic interactions between the Gd³⁺ ions. We prepared luminescent down-shifting layers (LDSL) with the 1, 3-6 complexes embedded in ethylene-vinyl-acetate and studied their effect in the external quantum efficiency (EQE) and intensity-voltage (I-V) plots of a solar mini-module. We found that LDSL containing the bimetallic complexes 3 and 6 enhance the efficiency of the solar mini-module from 11.26(3)% to 11.76(4)% (+0.52%) and to 11.44(2)% (+0.21%), respectively.

Synthesis and fluorescence properties of some difluoroboron β-diketonate complexes and composite containing PMMA

A series of difluoroboron β-diketonate complexes, containing the indon-β-diketonate ligand carrying methyl or methoxyl substituents was synthesized. The crystal structures of the complexes were confirmed by single crystal X-ray diffraction studies. The fluorescence properties of compounds were studied in solution state, solid state and on PMMA polymer matrix. The photophysical data of compounds 2a-2d exhibited strong fluorescence and photostability under the ultraviolet light (Hg lamp). The complex 2b showed higher fluorescence intensity in solution state as compared to other complexes of the series. The complexes 2c and 2d showed higher fluorescence intensity in the solid state, which are ascribed to the stronger π-π interactions between ligands in the solid state. The introduction of methoxyl or methyl groups on the benzene rings enhanced the absorption intensity, emission intensity, quantum yields and fluorescence lifetimes due to their electron-donating nature. Furthermore, the complex 2b was doped into the PMMA to produce hybrid materials, where the PMMA matrix acted as sensitizer for the central boron ion to enhance the fluorescence emission intensity and quantum yields.

(E)-4-Methyl-N-((quinolin-2-yl)ethylidene)aniline as ligand for IIB supramolecular complexes: synthesis, structure, aggregation-induced emission enhancement and application in PMMA-doped hybrid material

Judicious structural design employing 2-quinolinecarboxaldehyde and 4-methylaniline was used to generate the Schiff base ligand (E)-4-methyl-N-((quinolin-2-yl)ethylidene)aniline (L). Five IIB complexes, namely, [ZnLCl₂] (1), [ZnL(NO₃)₂] (2), [ZnL(OAc)₂]₃ (3), [CdL(OAc)₂]₃ (4), and [HgLCl₂] (5) have been synthesized based on L. Single-crystal X-ray diffraction analysis indicates that complexes 1, 3 and 4 exhibit 3D networks, whereas 2 and 5 form 2D layers and 1D chains, respectively. TD-DFT calculations show a good correlation with the UV-vis absorption assigned to π → π* intraligand transitions. Furthermore, complexes 1-5 displayed strong greenish luminescent emissions (518-524 nm) in the aggregate state but weak emissions in solution (aggregation-induced emission enhancement), which may be due to the existence of C-HCl/O hydrogen bonding and ππ stacking interactions, resulting in restriction of intramolecular rotation (RIR). Variable-concentration ¹H NMR studies suggested that the aggregates undergo intramolecular changes in conformation due to intermolecular interactions. Moreover, the emission intensity and lifetime exhibited obvious increases induced by mechanical grinding and temperature reduction, which were also attributed to AIEE properties. Subsequently, complex 1 was incorporated into poly(methyl methacrylate) (PMMA), whereby 1-PMMA exhibited enhanced emission intensity (20-fold increase in comparison with that of 1), which offers opportunities for use in plastic greenhouses to increase leaf photosynthesis.

Structure and magnetism of two chair-shaped hexanuclear dysprosium(iii) complexes exhibiting slow magnetic relaxation

Two novel hexanuclear Dy^III complexes with polyhydroxy Schiff-base ligands, [Dy₆(L¹)₄(μ₃-OH)₄(MeOH)₄]Cl₂·2MeOH·2MeCN (1) and [Dy₆(HL²)₂(μ₃-OH)₂(μ₃-OCH₃)₂(piv)₁₀(MeOH)₂] (2) (H₃L¹ = N,N′-bis(3-methoxysalicylidene)(propylene-2-ol)-1,3-diamine, H₃L² = 2,3-dihydroxypropylimino)methyl)-6-methoxyphenol, piv = pivalate), have been prepared under solvothermal conditions and structurally characterized by single-crystal X-ray diffraction, elemental analyses, thermal analyses, and IR spectroscopy. Each of the hexanuclear complexes is constructed with Dy₃ triangular motifs as building blocks, and the six Dy^III ions are arranged in a chair-shaped conformation. Variable-temperature magnetic susceptibility measurements in the temperature range of 2–300 K indicate dominant ferromagnetic exchange interactions between the Dy^III ions in the complexes. Both complexes exhibit slow magnetic relaxation behavior.

We report two novel chair-shaped hexanuclear Dy^III complexes with different polyhydroxy Schiff-base ligands. Both complexes are constructed with Dy₃ triangular motifs as building blocks and exhibit slow magnetic relaxation behavior at low temperature.

Tunable white-light emission PMMA-supported film materials containing lanthanide coordination polymers: preparation, characterization, and properties

A tunable white-light emission luminescence material W₍4-Eu_,5-Gd_,6-Tb₎-PMMA film is obtained by co-doping coordination polymers 4-Eu, 5-Gd, and 6-Tb within PMMA.

Different conjugated system Zn(ii) Schiff base complexes: supramolecular structure, luminescent properties, and applications in the PMMA-doped hybrid materials

Five Zn(ii) complexes with different conjugated systems were synthesized. Zn3 was incorporated into PMMA, creating a high performance material.

Photoluminescent polymer composites with R, G, B emission and their potential applications in LCD displays

Photoluminescent polymer composites with RGB emission were prepared, investigated and tested in a configuration which could replace the usual RGB filters in AMLCD displays.

Phase controlled colour tuning of samarium and europium complexes and excellent photostability of their PVA encapsulated materials. Structural elucidation, photophysical parameters and the energy transfer mechanism in the Eu3+ complex by Sparkle/PM3 calculations

Luminescence and photostability of new Sm and Eu complexes and those of their thin hybrid films have been investigated and discussed.

Near-infrared luminescence of Nd3+ and Yb3+ complexes using a polyfluorinated pyrene-based β-diketonate ligand

Highly efficient near-infrared emitting Nd³⁺ and Yb³⁺ complexes have been developed based on a new polyfluorinated pyrene-appended β-diketonate ligand.

Dual functional fluorescent sensor for selectively detecting acetone and Fe3+ based on {Cu2N4} substructure bridged Cu(i) coordination polymer

A novel red emission polymer can serve as a dual functional fluorescent sensor for selectively detecting trace amounts of acetone and Fe³⁺ though quenching the luminescence.

Preparation, characterization, and properties of PMMA-doped polymer film materials: a study on the effect of terbium ions on luminescence and lifetime enhancement

Poly(methylmethacrylate) (PMMA) doped with Tb-based imidazole derivative coordination polymer {[Tb(3)(L)(μ(3)-OH)(7)]·H(2)O}(n) (1) (L = N,N'-bis(acetoxy)biimidazole) was synthesized and its photophysical properties were studied. The L'(L' = N,N'-bis(ethylacetate)biimidazole) ligand was synthesized by an N-alkylation reaction process followed by ester hydrolysis to produce ligand L. Polymer 1 and ligand L' have been characterized by (1)H NMR and IR spectroscopy, elemental analysis, PXRD and X-ray single-crystal diffraction. Coordination polymer 1 is the first observation of a CdCl(2) structure constructed with hydroxy groups and decorated by ligand L in lanthanide N-heterocyclic coordination polymers. In the 2D layered structure of 1, each Tb3 metal center is connected with three Tb1 and three Tb2 metal centers by seven hydroxyl groups in different directions, resulting in a six-membered ring. After doping, not only the luminescence intensity and lifetime enhanced, but also their thermal stability was increased in comparison with 1. When 1 was doped into poly(methylmethacrylate) (1@PMMA), polymer film materials were formed with the PMMA polymer matrix (w/w = 2.5%-12.5%) acting as a co-sensitizer for Tb(3+) ions. The luminescence intensity of the Tb(3+) emission at 544 nm increases when the content of Tb(3+) was 10%. The lifetime of 1@PMMA (914.88 μs) is more than four times longer than that of 1 (196.24 μs). All τ values for the doped polymer systems are higher than coordination polymer 1, indicating that radiative processes are operative in all the doped polymer films. This is because PMMA coupling with the O-H oscillators from {[Tb(3)(L)(μ(3)-OH)(7)]·H(2)O}(n) can suppress multiphonon relaxation. According to the variable-temperature luminescence (VT-luminescence) investigation, 1@PMMA was confirmed to be a stable green luminescent polymer film material.

Luminescent properties of Ag(i)/Cu(i) coordination polymers: crystal structures and high intensity luminescence of a PMMA-doped hybrid material based on a quinoline-2,3-dicarboxylic acid ligand

Preparation, characterization, crystal structure and different luminescent properties of Ag(i)/Cu(i) coordination polymers: stable blue emission, thermochromism and PMMA-doped hybrid material.

Europium-doped LaF3nanocrystals with organic 9-oxidophenalenone capping ligands that display visible light excitable steady-state blue and time-delayed red emission

Visible light excitable 9-oxidophenalenone-coated LaF₃:Eu NCs display steady-state blue and time-delayed red emission; capping ligands act as probes to reveal three different Eu³⁺sites with distinct emission properties.