Near-Infrared Luminescent Hybrid Materials Doped with Lanthanide (Ln) Complexes (Ln = Nd, Yb) and Their Possible Laser Application

Optical, electrochemical and photophysical analyses of heteroleptic luminescent Ln(iii) complexes for lighting applications

A series of lanthanide complexes have been synthesized with fluorinated 1,3-diketones and heteroaromatic ancillary moieties. Spectroscopic studies reveal the attachment of the respective lanthanide ion to the oxygen site of β-diketone and nitrogen site of auxiliary moieties. The conducting behavior of the complexes is proposed by their optical energy gaps which lie in the range of semiconductors. The emission profiles of the lanthanide complexes demonstrate red and green luminescence owing to the distinctive transitions of Sm³⁺ and Tb³⁺ ions, respectively. Energy transfer via antenna effect clearly reveals the effective transfer of energy from the chromophoric moiety to the Ln³⁺ ion. The prepared conducting and luminescent Ln(iii) complexes might be employed as the emitting component in designing OLEDs.

Fluorinated β-diketone-based Sm(III) complexes: spectroscopic and optoelectronic characteristics

The synthesis and characterization of a series of octa-coordinated Sm(III) complexes with 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione (TFNB) and 2,2'-bipyridine (Bpy) derivatives as ancillary ligand are described here. The complexes were analyzed by elemental, spectroscopic such as infrared spectroscopy, ¹ H NMR, and thermogravimetric analyses. The fluorinated TFNB ligand absorbs in the range from 200 to 400 nm. The complexes show the sharp and structured Sm-based emissions in visible region upon irradiation in UV range. Excitation spectra of complexes show similarity to the absorption spectra of ligands suggesting that excitation energy is transferred from ligands to Sm(III) centre by the antenna effect. Photoluminescence emission spectra and colour parameters affirmed that the complexes show luminescence in orange-red region. These luminous Sm(III) complexes might be applied as emissive layer in organic electroluminescent devices.

Ultrasensitive near-infrared electrochemiluminescence biosensor derived from Eu-MOF with antenna effect and high efficiency catalysis of specific CoS2 hollow triple shelled nanoboxes for procalcitonin

In this paper, we report a novel multiple amplification strategy for ultrasensitive near-infrared electrochemiluminescence (ECL) immunoassay in K₂S₂O₈ solution. The realization of this strategy is based on the antenna effect of Eu-MOF (EuBTC) and a high efficiency catalysis of CoS₂ hollow triple shelled nanoboxes (TSNBs). The H₃BTC ligand in the antenna effect first undergoes π-π* absorption and a singlet-singlet electronic transition. Its energy passes through the intersystem to the triplet state, next transfers from the lowest excited triplet state to the vibrational energy level of the rare earth ion, finally realizing sensitizing center ion luminescence. Moreover, ionic reaction and structural advantages endow CoS₂ TSNBs a dual signal enhancement effect. This sandwich-type ECL biosensor has a near-infrared luminescence in 800-900 nm, thus avoiding damage to the sample in the meantime. In practical diagnosis, the normal critical value of procalcitonin (PCT) (<0.5 ng/mL) is much higher than the detection limit (3.65 fg/mL) and is in the detection range (10 fg/mL-100 ng/mL), which means that the ECL biosensor has a high sensitivity in the detection of PCT and meet the requirement for diagnosis of disease completely. Therefore, the strategy provides a feasible method for efficient and stable analysis of systemic inflammatory response such as fearful bacterial infection, hepatitis B, and peritonitis.

Near-infrared/visible-emitting nanosilica modified with silylated Ru(II) and Ln(III) complexes

Three luminescent silica-based nanohybrids were fabricated by grafting of silylated Ru(II) and Nd/Yb(III) complexes onto mesoporous silica nanoparticles obtained by microemulsion method. The prepared nanohybrids were characterized by Fourier transform-Raman spectroscopy, solid state-nuclear magnetic resonance, high resolution-transmission electron microscopy and scanning and transmission electron microscopy techniques. The chemical integrity and the grafting of all complexes inside MSNs nanopores as well as a good distribution of metal complexes onto MSNs surface were achieved for all nanohybrids. Photophysical results revealed that by monitoring the excitation on Ru(II) moieties from SiO ₂ -RuNd and SiO ₂ -RuYb nanohybrids, the sensitization of NIR-emitting Nd/Yb(III) ions were successfully detected via energy transfer processes. Energy transfer rates (k _EnT) of 0.20 × 10⁷ and 0.11 × 10⁷ s^-1 and efficiencies of energy transfer (η _EnT) of 40% and 27.5% were obtained for SiO ₂ -RuNd and SiO ₂ -RuYb nanohybrids, respectively. These results confirm the preparation of promising dual (near-infrared/visible)-emitting silica-based nanohybrids as new nanotools for applications as nanosensores and nanomarkers.

Bright neodymium complexes for efficient near infra-red organic light emitting diodes

This paper reports the synthesis, structures, and photophysical and electroluminescence properties of low symmetry NIR emitting octa- and nona-coordinate Nd tris β-diketonate complexes.

Lanthanide-Based Luminescent Materials for Waveguide and Lasing

Microlasers and waveguides have wide applications in the fields of photonics and optoelectronics. Lanthanide-doped luminescent materials featuring large Stokes/anti-Stokes shift, long excited-state lifetime as well as sharp emission bandwidth are excellent optical components for photonic applications. In the past few years, great progress has been made in the design and fabrication of lanthanide-based waveguides and lasers at the micrometer length scale. Waveguide structures and microcavities can be fabricated from lanthanide-doped amorphous materials through top-down process. Alternatively, lanthanide-doped organic compounds featuring large absorption cross-section can self-assemble into low-dimensional structures of well-defined size and morphology. In recent years, lanthanide-doped crystalline structures displaying highly tunable excitation and emission properties have emerged as promising waveguide and lasing materials, which substantially extends the range of lasing wavelength. In this minireview, we discuss recent advances in lanthanide-based luminescent materials that are designed for waveguide and lasing applications. We also attempt to highlight challenging problems of these materials that obstacle further development of this field.

Novel luminescent lanthanide(iii) hybrid materials: fluorescence sensing of fluoride ions and N,N-dimethylformamide

Two novel luminescent organic-inorganic hybrid materials, Ln(L-SBA15)3phen (Ln = Eu, Tb), were designed and synthesized. The organic ligand phenylurea was modified by the silane coupling agent 3-(triethoxysilyl)propyl isocyanate (TESPIC) to form a precursor (L), which was covalently bonded onto a mesoporous SBA-15 backbone to form mesoporous L-SBA15 through co-hydrolysis and co-condensation reactions. 1,10-Phenanthroline monohydrate (phen) was selected as the second ligand to improve the luminescence of the final products, and the two mesoporous hybrid materials Ln(L-SBA15)3phen were obtained after the coordination reaction between the organic ligands (phen and L-SBA15) and Ln(iii) ions. Both the mesoporous hybrid materials were examined by Fourier transform infrared spectroscopy, transmission electron microscopy, small-angle X-ray diffraction, N2 adsorption-desorption curves, and photoluminescence spectroscopy. The results show that both the hybrid materials showed highly ordered mesoporous structures, high surface areas, and excellent photophysical properties (long luminescence lifetimes and high quantum efficiencies). Furthermore, the fluorescence sensing properties of the materials were investigated systematically, and the hybrid materials were revealed to be promising examples of dual functional materials with good ability to sense fluoride ions and a small organic molecule N,N-dimethylformamide.

Refractive Index Tuning of Hybrid Materials for Highly Transmissive Luminescent Lanthanide Particle-Polymer Composites

High-refractive-index ZrO₂ nanoparticles were used to tailor the refractive index of a polymer matrix to match that of luminescent lanthanide-ion-doped (La_0.92Yb_0.075Er_0.005F₃) light-emitting particles, thereby reducing scattering losses to yield highly transparent emissive composites. Photopolymerization of blends of an amine-modified poly(ether acrylate) oligomer and tailored quantities of ZrO₂ nanoparticles yielded optically transparent composites with tailored refractive indices between 1.49 and 1.69. By matching the refractive index of the matrix to that of La_0.92Yb_0.075Er_0.005F₃, composites with high transmittance (>85%) and low haze from the visible to infrared regions, bright 1530 nm optical emissions were achieved at solids loadings of La_0.92Yb_0.075Er_0.005F₃, ranging from 5 to 30 vol %. These optical results suggest that a hybrid matrix approach is a versatile strategy for the fabrication of functional luminescent optical composites of high transparency.

Probing the effect of β-triketonates in visible and NIR emitting lanthanoid complexes

Investigating the effect of the third ketone arm on the photophysics of visible and NIR emitting lanthanoid β-triketonate complexes.

A Series of Lanthanide-Germanate Oxo Clusters Decorated by 1,10-Phenanthroline Chromophores

A series of lanthanide-germanate oxo clusters, [Ln₈(phen)₂Ge₁₂(μ₃-O)₂₄T₁₂(H₂O)₁₆]·2H₂O [Ln = Dy (1a) and Er (1b); T = -CH₂CH₂COO^- group; phen = 1,10-phenanthroline], [Ln₈(phen)₂Ge₁₂(μ₃-O)₂₄T₁₂(H₂O)₁₆]·2phen·16H₂O [Ln = Sm (2a), Eu (2b), and Gd (2c)], and [Ho₈(phen)₂Ge₁₂(μ₃-O)₂₄T₁₂(H₂O)₁₄]·2phen·13H₂O (3), have been hydrothermally synthesized from the reactions of bis(carboxyethylgermanium sesquioxide) and Ln₂O₃ with auxiliary phen chromophores. Compounds 1a and 1b consist of cage clusters [Ln₈(phen)₂Ge₁₂(μ₃-O)₂₄T₁₂(H₂O)₁₆] and free H₂O molecules, where cage clusters are arranged in a CsCl type, while compounds 2a-2c consist of cage clusters [Ln₈(phen)₂Ge₁₂(μ₃-O)₂₄T₁₂(H₂O)₁₆], free phen, and free H₂O molecules, where cage clusters are arranged in a NaCl type. Compound 3 consists of the one-dimensional neutral chain [Ho₈(phen)₂Ge₁₂(μ₃-O)₂₄T₁₂(H₂O)₁₄]_n and free H₂O molecules. These compounds provide the first examples of p-f heterometallic [Ge-O-Ln] oxo clusters decorated by phen chromophores. The photoluminescent and magnetic properties of all compounds have been investigated.

Synthesis, Characterization and Properties of Novel Coumarin Derivatives and Their Europium Complexes

Seven novel coumarin derivatives derived from salicylaldehyde and phenol were synthesized and characterized by (1)H NMR and (13)C NMR spectra, mass spectra, infrared spectra and elemental analysis. Their corresponding Eu(III) complexes having general formula EuL(1-7)(NO3)3[Symbol: see text]2H2O were successfully prepared and characterized by elemental analysis, EDTA titrimetric, molar conductivity, UV-Vis, FT-IR and thermal performance studies. The luminescence properties, fluorescence quantum yields and the electrochemical properties of the title complexes were investigated. The results showed that the title complexes exhibited characteristic emissions of europium ions and possessed relatively good fluorescence quantum yields. The luminescence intensity of the complex with bromine-substituted group is the strongest among all the title complexes. The introduction of electron-withdrawing groups can increase the luminescence properties and fluorescence quantum yields, decrease the HOMO and LUMO energy levels of the title europium complexes, but electron-withdrawing group conversely. And these title complexes may possibly be useful for studying in luminescent materials field. Graphical Abstract Synthesis route of the ligands L (1-7).

Tuning of the excitation wavelength in Eu3+-aminophenyl based polyfluorinated β-diketonate complexes: a red-emitting Eu3+-complex encapsulated in a silica/polymer hybrid material excited by blue light

A series of new antenna complexes of Eu³⁺ based on aminophenyl β-diketonate ligands was designed and their photophysical properties were evaluated.

Lanthanoid β-triketonates: a new class of highly efficient NIR emitters for bright NIR-OLEDs

A bimetallic tetranuclear Yb³⁺/K⁺ complex obtained using β-triketonate ligands was found to be a suitable precursor for the fabrication of near-infrared Organic Light Emitting Devices that outclass any other previously reported lanthanoid-based near-infrared device.

Novel photofunctional hybrid materials (alumina and titania) functionalized with both MOF and lanthanide complexes through coordination bonds

Multi-component sol–gel derived alumina and titania hybrid materials are assembled by the functionalization of both lanthanide complexes and a special metal organic framework compound: Al-MIL-53-COOH through coordination bonds. Multi-color luminescence and white colored light can be tuned by controlling the different units in the hybrid system.

Near infrared and visible luminescence from xerogels covalently grafted with lanthanide [Sm(3+), Yb(3+), Nd(3+), Er(3+), Pr(3+), Ho(3+)] β-diketonate derivatives using visible light excitation

A series of ternary lanthanide β-diketonate derivatives covalently bonded to xerogels (named as Ln-DP-xerogel, Ln = Sm, Yb, Nd, Er, Pr, Ho) by doubly functionalized alkoxysilane (dbm-Si) was synthesized in situ via a sol-gel process. The properties of these xerogel materials were investigated by Fourier-transform infrared (FT-IR) spectroscopy, field-emission scanning electron microscopy (FE-SEM), diffuse reflectance (DR) spectroscopy, thermogravimetric analyses, and fluorescence spectroscopy. The data and analyses suggest that the lanthanide derivatives have been covalently grafted to the corresponding xerogels successfully. Of importance here is that, after excitation with visible light (400-410 nm), the xerogels all show characteristic visible (Sm(3+)) as well as near-infrared (NIR; Sm(3+), Yb(3+), Nd(3+), Er(3+), Pr(3+), Ho(3+)) luminescence of the corresponding Ln(3+) ions, which is attributed to the energy transfer from the ligands to the Ln(3+) ions via an antenna effect. Exciting with visible light is advantageous over UV excitation. Furthermore, to the best of our knowledge, it is the first observation of NIR luminescence with visible light excitation from xerogels covalently bonded with the Sm(3+), Pr(3+), and Ho(3+) derivatives. Compared to lanthanide complexes (Ln = Er, Nd, Yb) functionalized periodic mesoporous organosilica (PMO) materials that exhibit similar optical properties reported in our previous work, the Ln-DP-xerogel (Ln = Sm, Yb, Nd, Er, Pr, Ho) in this case offer advantages in terms of ease of synthesis and handling and potentially low cost for emerging technological applications. Development of near-infrared luminescence of the lanthanide materials with visible light excitation is of strong interest to emerging applications such as chemosensors, laser systems, and optical amplifiers.

Photofunctional hybrids of rare earth complexes covalently bonded to ZnO core-shell nanoparticle substrate through polymer linkage

A novel series of multi-component hybrids are assembled based on rare earth coordinated to rare earth ion (Eu(3+), Tb(3+), Sm(3+), Dy(3+)) complex systems and ZnO nanocomposites through three different ester units (ethyl methacrylate (EMA), 2-hydroxyethyl methacrylate (HEMA) and 2,2,3,4,4,4-hexafluorobutyl methacrylate (HFMA)) as functional polymer linkages. Methacrylic-group-modified ZnO nanoparticles (designated ZnO-MAA) are synthesized based on the reaction between zinc methacrylate and LiOH with the molar ratio 1 : 3.5 via sol-gel process. The final hybrid materials are prepared by introducing rare earth complexes into ZnO-MAA matrix via addition polymerization reaction in the presence of benzoyl peroxide (BPO) as the initiator. The detailed characterization and luminescence of these hybrid materials are discussed. It is found that ZnO-MAA-HEMA/EMA/HFBMA-RE-phen hybrid systems have effective intramolecular energy transfer process and exhibit longer lifetime and higher quantum efficiency.