Luminescent Hybrid Materials Research Articles

Optical properties of a new luminescent hybrid material [C6N2H5]3BiCl6 involving a resonance energy transfer (RET)

This paper reports on the optical properties of new organic metal halide material [C6N2H5]3BiCl6. The crystal structure is built up from the packing of distorted [BiCl6]3- octahedra surrounded by organic cation [C6N2H5]+. Unlike the classical metal halide materials in which organic molecules are optically inactive, both organic and inorganic components in this structure are chromospheres. At ambient temperature, photoluminescence measurements show and intense emission in the yellow green region. This emission is believed to be due to π– π* electronic transition within the organic cation [C6N2H5]+. Optical absorption (OA) and photoluminescence (PL) spectra of this compound were analyzed and interpreted by comparison with those of the homologous hybrids on one hand and those of the organic molecules on the other hand. In addition, photoluminescence excitation (PLE) have shown that the intense emission is governed by a resonance energy and charge transfer process in which [BiCl6]3- ions is assumed as a donor and organic cation plays the role of an acceptor. Moreover, photoluminescence study as function of temperature using the Arrhenius model, reveals the behavior a quasi-localized exciton with a binding energy of 73 meV, substantially lower than those found for homologous compounds but it reflects the localized character of the exciton and it may explain the stability of the exciton at ambient temperature.

Luminescent hybrid materials based on metal-organic phosphors in PbF2 powder and PbF2-containing glass matrix

The new hybrid materials (HM's) are based on the phosphors used in OLED technology in inorganic PbF2-containing matrices: PbF2 powders and low melting PbF2-based oxyfluoride glasses, were synthesized. We used highly effective thermostable phosphors: 4,4,5,5,6,6,7,7,8,8,9,9,9-tridecafluoro-1- (1-methyl-1H-pyrazol-4-yl) nonane-1,3-dione - (1,10-phenanthroline) europium (III), 8-hydroxyquinoline complexes with metals and the individual organic ligand – 4,4,4-trifluoro-1- (2-naphthyl) butane-1,3-dione. Powdered HM's were prepared by co-precipitation from aqueous solutions. The effect of organic molecules or molecular fragments on dimension and morphology of precipitated PbF2 particles, the luminescence properties of HM's were investigated for the samples obtained directly after the precipitation-drying procedure, and after the powders' calcination procedure. The change in the photoluminescence spectra after the heat treatment of the powders is caused by the proceeding of the exchange reaction between the metal complex and the matrix with the formation of Pb-complexes of different coordination is shown. HM (glasses PbF2B2O3, PbF2B2O3SiO2 or PbF2B2O3SiO2ZnO phosphor) were obtained by the melt process in which the phosphor powder was submerged into the melt of the pre-synthesized glasses.

Synthesis of Luminescent Gold Nanoclusters Embedded Goose Feathers for Facile Preparation of Au(I) Complexes with Aggregation-Induced Emission

A new kind of luminescent hybrid materials based on ultrasmall nanomaterials, that is, gold nanoclusters (AuNCs) and goose feathers, precious gifts from nature, has been successfully synthesized. Goose feathers possess high specific surface area due to their hierarchical structure and are mainly composed of thiol-rich proteins, for example, keratin, which can reduce Au(III) and encapsulate the formed AuNCs in a large scale. The resultant golden feathers exhibit bright red luminescence under UV light, of which the substructures, that is, barbs and barbules, have been sufficiently stained with red-emitting AuNCs. Furthermore, the AuNC-stained feathers maintain almost unchanged structure (solid and hierarchical) and intact chemical composition. The features of such AuNC/feather hybrids, for example, bulk, high specific surface, inspired us to develop a facile method to prepare various valuable debris from AuNC-based etching, that is, Au(I) complexes with aggregation-induced emission (AIE). We selected tris(2...

Tunable multi-color luminescence and white emission in lanthanide ion functionalized polyoxometalate-based metal–organic frameworks hybrids and fabricated thin films

In this paper, luminescent hybrid material systems are prepared with porous polyoxometalate-based metal–organic framework (POM-based MOF)[La(H2O)4(pdc)]4}[SiMo12O40]·2H2O (1) through the introduction of lanthanide ions (Ln3+, Ln = Eu, Tb, Sm, Dy, Eu/Tb, Dy/Eu) by a solvothermal approach. The POM-based MOF serves as a host for protecting the luminescence of Ln3+ cations. The structure, thermal stability, ultraviolet absorption and visible light emission of the target hybrid materials are determined with powder X-rays diffraction patterns (PXRD), Fourier transform infrared spectra (FTIR), thermalgravimetric analysis (TGA), inductively coupled plasma-mass spectrometry (ICP-MS) analysis, energy dispersive spectrometer (EDS), ultraviolet visible diffusion reflections spectra (UV–vis DRS) and especially luminescence spectra. The final luminescence of the Ln3+ hybrids can be adjusted by changing the composition of Ln3+ cations or converting the excitation wavelengths of them. Among [La0.95Dy0.045Eu0.005(H2O)4(pdc)]4}[SiMo12O40]·2H2O (Dy3+/Eu3+@1) emits white luminescence under the excitation at 295 nm and the Commission Internationale de L'Eclairage (CIE) chromaticity coordinate of it is (0.361, 0.3408). Moreover, we manufacture POM-based MOF thin films by using ethyl methacrylate (EMA) to assemble the POM-based MOF on a quartz plate as substrate. The hybrid thin films based on {La0.95Eu0.05(H2O)4(pdc)]4}[SiMo12O40]·2H2O (Eu3+@1) and La0.95Eu0.04Tb0.01(H2O)4(pdc)]4}[SiMo12O40]·2H2O (Eu3+/Tb3+ @1) can also achieve white-light. The CIE chromaticity coordinates of them are (0.3425, 0.2548) and (0.3857, 0.3377), respectively.

Coupling Photoluminescence and Ionic Conduction Properties Using the Different Coordination Sites of Ureasil-Polyether Hybrid Materials.

In this article, we demonstrate that each functional group of ureasil organic-inorganic hybrid (OIH) materials can act as a specific coordination site for a given active guest species, hence allowing the possibility of combining different functional properties. To illustrate this concept, the sol-gel process was used to produce diurea cross-linked siloxane-polyethylene oxide (U-PEO) and siloxane-polypropylene oxide (U-PPO) hybrid host frameworks with similar molecular weights (1900 and 2000 g mol-1 for PEO and PPO, respectively), with Li+ and Eu3+ as active guest ions providing ionic conduction and photoluminescence (PL) properties, respectively. Comparison of Fourier transform infrared spectra and small-angle X-ray scattering results for single-doped (using Li+ or Eu3+) and co-doped (using Li+ and Eu3+) U-PEO and U-PPO hosts showed that in every case, there was specific coordination of Eu3+ by the carbonyl group of the urea bridge and of Li+ by ether-type oxygen of the PEO and PPO chains. Optical analyses demonstrated that loading with Li+ did not affect the luminescence properties of the Eu3+-loaded OIH. Although loading with Eu3+ had a small effect on ionic transport, co-doping with Li+ ions ensured macroscopic ion-conduction of the transparent and luminescent hybrid material. The results suggested that the combination of both properties in a transparent elastomeric material could be useful for the development of multifunctional devices. The results suggested that the combination of both properties in a transparent elastomeric material could be useful for the development of multifunctional polyelectrolytes applied in the field of dual luminescent devices such as photoelectrochromic smart windows.

Multifunctional Ionogels Incorporated with Lanthanide (Eu3+, Tb3+) Complexes Covalently Modified Multi-Walled Carbon Nanotubes.

Ionogels refer to an emerging composite material made from the confinement of ionic liquids within some specific cross-linked network matrices. They have potential applications in areas such as electrochemical and optical-electric materials. Incorporation of lanthanide (Eu3+, Tb3+) complexes covalently functionalized multi-walled carbon nanotubes (MWCNTs) in ionogels provide new ideas to design and synthesize novel luminescent hybrid materials that have excellent characteristics of luminescence and ionic conductivity. Here, the multifunctional ionogels were synthesized by confining an ionic liquid and the rare earth functionalized MWCNTs in the cross-linked polymethyl methacrylate (PMMA) networks, resulting in a novel optical/electric multifunctional hybrid material. The SEM images and digital photographs suggest that the lanthanide functionalized MWCNTs are evenly dispersed in the hybrid matrices, thus leading to a certain transparency bulky gel. The resulting ionogels exhibit certain viscosity and flexibility, and display an intense red/green emission under UV-light irradiation. The intrinsic conductibility of the embedded ionic liquids and carbon nanotubes in conjunction with the outstanding photoluminescent properties of lanthanide complexes makes the soft hybrid gels a material with great potential and valuable application in the field of optical-electric materials.

Hybrid materials based on PEGDMA matrix and europium(III) carboxylates -thermal and luminescent investigations

The synthesis and characterization of luminescent hybrid materials containing three different europium(III) complexes incorporated into the polymeric host during the copolymerization process with the commercially available monomer: ethylene glycol dimethacrylate (EGDMA) is reported. A new method of synthesis of organic–inorganic materials in the form of microspheres was proposed. The chemical structure of these materials was confirmed by the ATR–FTIR analysis. Thermal stability and pathways of thermal decomposition of the luminescent europium(III) complexes as well as obtained materials were investigated by means of the thermal analysis methods (TG–DTG–DSC) in air and inert atmosphere. Volatile products of thermal decomposition of polymeric matrix and hybrid materials were analyzed by the TG–QMS method. Luminescence properties of the complexes as dopants in the obtained materials were investigated in detail.

Luminescent mesoporous hybrid materials grafted with lanthanide complexes synthesized by Michael-like addition reaction

New kind of luminescent mesoporous hybrid materials were prepared via Michael-like addition reaction. 4-Vinylpyridine-2,6-dicarboxylic acid was selected as a bifunctional chelating ligand, which contains (1) an electron deficient double bond that can react with the thiol group of mesoporous silica by Michael-like addition reaction, (2) a metal chelating unit. The luminescent hybrid materials [MCM-41-SH-Ln(DPA)3, Ln = Tb, Eu] can be prepared through Michael-like addition reaction of thiol-functional MCM-41 and 4-vinylpyridine-2,6-dicarboxylic acid, and then assembling with lanthanide ions and pyridine-2,6-dicarboxylic acid (DPA). FT-IR, XRD, UV–Vis, TEM, N2 adsorption/desorption and photoluminescence measurements were employed to characterize the mesostructure, composition and optical properties of these hybrids. The results reveal that the lanthanide complexes were successfully grafted onto the functional MCM-41, and the ordered mesoporous structure of MCM-41 were preserved after the grafting procedure. Under the excitation of UV light, the obtained MCM-41-SH-Tb(DPA)3 and MCM-41-SH-Eu(DPA)3 exhibit bright green and red emission, long luminescent lifetimes and high quantum efficiency.

White light color tuning ability of hybrid Dibenzoylmethane/YAG:Ce nanophosphor

In this study, we have considered the synthesis of a novel hybrid material consisting of cerium-doped yttrium aluminium garnet (YAG:Ce) nanophosphor surface decorated by UV/blue sensitizing Dibenzoylmethane (DBM) organic molecule. A comparative evaluation of synthesized hybrid material YAG:Ce/DBM nanophosphor and YAG:Ce nanophosphors was made using a combination of different analytical techniques like X-ray diffraction, Scanning electron microscopy, UV–Visible-Infrared absorption, Photoluminescence techniques etc. Due to the presence of organic ligand, the hybrid nanophosphor has extended excitation.We have monitored the emission spectra at excitation with 355 nm, 375 nm, 405 nm, and 465 nm. The synthesized luminescent hybrid material was characterized by various spectroscopic techniques and its photophysical properties were thoroughly investigated. The color perception of hybrid YAG:Ce/DBM nanophosphor is significantly modified due to the mixing of blue color in the green-yellow emission of YAG:Ce nanophosphor at different excitations which yield CIE coordinates (0.37, 0.59).

Ln(III)-Functionalized Metal–Organic Frameworks Hybrid System: Luminescence Properties and Sensor for trans,trans-Muconic Acid as a Biomarker of Benzene

By application of a straightforward postsynthetic modification strategy, a luminescent lanthanide-based MOFs hybrid material, Tb(III)@MOF-SO3-, is first fabricated by loading Tb(III) ions into the pores of Zn-based MOF-SO3-. This hybrid system is constructed on notable and specific luminous sensitization of MOF-SO3- to Tb(III) ions. The further study shows that bi-metal-loaded Eu(III)/Tb(III)@MOF-SO3- exhibits a Tb(III)-induced luminescence of Eu(III) ions, and the emissions of it all fall in the white region by altering the ratio of Eu(III)/Tb(III) ions and the excitation wavelengths. A kind of white-lighting thin film based on Eu(III)/Tb(III)@MOF-SO3- exhibits dazzling white light when excited at 295 nm ( X = 0.338, Y = 0.323). Furthermore, the Tb(III)@MOF-SO3- is first developed as a fluorescence sensor specifically toward biomarker of benzene, trans, trans-muconic acid ( tt-MA), based on fluorescence quenching. This reusable sensor with high water tolerance and photostability displays excellent selectivity and sensitivity with a detection limit as low as 0.1 ppm, while being provided with the high antijamming of other urinary chemicals. These results make the sensor has the potential for the practical detection of tt-MA in a urine system. The possible quenching mechanisms are also investigated in detail.

Synthesis and Luminescent Properties of Europium Complexes Covalently Bonded to Hybrid Materials Based on MCM-41 and Poly(Ionic Liquids).

Due to the wide potential application in the fields of sensing, lighting materials, and optical–electrical multifunctional devices, rare earth complex hybrid materials have been studied extensively over the past decades. A poly(ionic liquid)/mesoporous-based hybrid system which has been functionalized by the covalently linked europium complexes was reported here. Through surface modification with a coupling agent bearing an vinyl group, MCM-41 was chosen as the carrier matrix for poly(ionic liquids) (PILs) and europium compounds, and based on that, novel luminescent hybrid materials were prepared by confining the ionic liquid and europium complexes into the inorganic Si–O frameworks. The resulting organic/inorganic materials are chemically bonded hybrids which show good photoluminescent properties such as broad excitation spectra, line-like emission spectra, and long luminescence lifetimes. The PILs/MCM-41/Eu3+ hybrid reported here is a rare earth multifunctional material which is believed to have potential applications in the field of optical–electrical materials.

Luminescent Hybrid Materials Based on Curcumin Derivatives Embedded in Palygorskite

The seven curcumin derivatives were deposited on palygorskite in order to obtain hybrid materials. The fluorescence emission spectra of the obtained materials show a decrease in fluorescence intensity relative to the respective dyes, due to the environments around the dyestuff molecules created in the host matrices. Absorption studies show the best adsorption on the inorganic matrix, for the compounds with the hydroxyl groups. Correlating fluorescence spectra of hybrid materials with the results for absorption spectra of the dyes adsorbtion on the surface of the clay lead to the conclusion that a high percentage of the adsorbed dye had the effect of fluorescence quenching. Thus, it was confirmed that the fluorescent properties of hybrid materials depend on the interactions established between the fluorescent dyestuff and the inorganic network.

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.

Luminescent liquid crystalline hybrid materials by embedding octahedral molybdenum cluster anions with soft organic shells derived from tribenzo[18]crown-6.

Crown ethers and their derivatives are versatile building blocks for the design of supramolecular materials. They can be functionalized at will and are well known for their abilities to complex with alkali cations. Here, we show that emissive lanthanide free hybrid materials can be generated by using such building blocks. The organic tribenzo[18]crown-6 central core was functionalized via six-fold Suzuki cross-coupling as a key reaction with three o-terphenyl units which could be converted into their corresponding triphenylenes by the Scholl reaction, leading to novel liquid-crystalline columnar materials. Selected tribenzo[18]crown-6 o-terphenyls could interact with emissive ternary metal cluster compound salts to generate hybrid materials combining the properties of both moieties. Due to synergistic effects and despite the anisometry of the cluster compounds, individual properties such as liquid-crystalline phase stability of the organic part and emission abilities of its inorganic counter-part are enhanced in the hybrid compounds.

A novel luminescent hybrid material based on zinc complexes and graphene oxides for detection of Fe3+ in aqueous media.

Graphene oxide sheet-modified zinc complexes named Zn-PMA/GOSs have been synthesized based on the non-covalent interactions of Zn-PMA and graphene oxide sheets (GOSs) via an in situ reaction. Then, the as-synthesized products are characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and fluorescence spectroscopy. Zn-PMA/GOSs not only show strong luminescence intensity and better thermal stability than pure zinc complexes but also have good dispersibility in aqueous solutions, and they are further used as fluorescence probes for detecting Fe3+. They show relative selectivity and high sensitivity to Fe3+ (Stern-Volmer constant KSV = 4 × 106 L mol-1), suggesting that Zn-PMA/GOSs can be a promising luminescent probe for selectively sensing Fe3+ ions. Moreover, the possible mechanisms of ion-selective detection are also discussed.

Luminescent hybrid materials based on nanodiamonds

Luminescent hybrid materials were prepared by covalently functionalizing nanodiamonds (NDs) with rare earth (RE) complexes. Pyromellitic acid (PMA), as the organic sensitizer, was grafted onto amino-terminated NDs to chelate lanthanide ions (Eu3+ and Tb3+). The emission colors of the hybrid composite of ND-PMA-EuxTby can be tuned from red to orange, yellow and green by adjusting the molar ratio of Eu3+ to Tb3+. Moreover, the luminescence of the hybrid composites exhibits remarkable photostability under ultraviolet irradiation for 60 h. As a proof-of-concept experiment, the as-synthesized ND-PMA-Eu and ND-PMA-Tb were employed as the phosphors for red and green light-emitting-diode (LED) devices with ultraviolet (UV) chips. Therefore, the nanodiamond-based luminescent hybrid material may find potential application in optical device.

Efficient Energy Transfer in Terbium Complexes/Porous Boron Nitride Hybrid Luminescent Materials

A novel kind of organic–inorganic hybrid luminescent material has been developed through controllable encapsulation of devise terbium(III) complexes into a porous boron nitride (BN) host. The luminescence of the obtained hybrid materials can be modulated by simply changing the type of ligands in the complexes. Especially, intense green-light-emission has been observed in Tb(acac)3/BN (acac = acetylacetone) and Tb(acac)3phen/BN (phen = 1,10-phenanthroline) hybrid materials. A unique synergistic effect between the BN host and Tb complexes has been realized, resulting in efficient energy transfer in the BN-ligands-Tb3+ system. The confinement of terbium complexes into porous BN leads to the hybrid materials demonstrating excellent thermal and photo stabilities. Porous BN host plays an important role for the superior performance of the hybrid materials. The developed organic–inorganic hybrid materials with multifunctional properties are promising for light-emitting applications.

Tunable white-light emission of lanthanide(III) hybrid material based on hectorite

In this work, we present novel trivalent lanthanide ions (Ln3+)-based luminescent hybrid materials, in which the organic ligands are covalently grafted on the hectorite templates and the Ln3+ ions can be well immobilized by the ligands through coordination bond. The hybrid materials exhibit tunable emission colors by varying the molar ratio of Eu3+ to Tb3+, and the one with Eu3+:Tb3+=1:1 exhibits excellent co-ordinate of (0.327, 0.328) located in the “white region” of the CIE 1931 chromaticity diagram (under 300nm UV illumination). These properties make the hybrid composites suitable for fabricating optoelectronic devices such as full-color displays and white LED.

A Eu(III) doped metal-organic framework conjugated with fluorescein-labeled single-stranded DNA for detection of Cu(II) and sulfide

In this paper, Bio-MOF-1 is prepared as reported and then Eu3+ is introduced into it via cation exchange method. A FAM-labeled ssDNA is chosen to fabricate with the obtained Eu3+@Bio-MOF-1. A luminescent hybrid material is assembled, which can exhibit the fluorescence of Eu3+ and FAM simultaneously by adjusting the ratio of FAM-ssDNA and Eu3+@Bio-MOF-1. The sample is then used for the detecting of metal ions, results shows which has good selectively for Cu2+ (LOD = 0.14 μM, 0–250 μM). The introduction of Cu2+ can quench the fluorescence of FAM while the luminescent intensity of Eu3+ enhancing. After the detection of Cu2+, the Cu2+ involved hybrid system can then be further employed for the detection of S2− (LOD = 1.3 μM, 0–50 μM). Low concentration of S2− can make the luminescent intensity of Eu3+ decrease gradually while high concentration of S2− can further recover the luminescent of FAM, which is quenched by Cu2+.

Exfoliation of zinc-layered hydroxide by luminescent conjugate polyelectrolyte: synthesis and photophysical aspects

Exfoliation of layered materials is of significant interest for both the fundamental scientific studies and technological applications. In this work, the π-conjugated polymer, poly[5-methoxy-2-(3-sulfopropoxy)-1,4-phenylenevinylene] potassium (MSP-PPV), was intercalated/exfoliated between the lamellae of the zinc-layered hydroxide (ZHL) to produce luminescent hybrid materials. This process is highly attractive because the intercalation/exfoliation of the MSP-PPV polymer in the sheets of zinc-layered hydroxide was realized by anionic exchange at room temperature. Depending on the amount of polyelectrolyte used in the preparation of the hybrid compounds (MPS-PPV/ZHL), the intercalation reaction was followed by exfoliation of the zinc-layered hydroxide layers. At higher MSP-PPV concentration used in the experiment, the resulting material presented a high degree of exfoliation of the zinc-layered hydroxide sheets, as suggested by both the X-ray diffraction and scanning electron microscopic images. Elemental analysis, nuclear magnetic resonance and Fourier transform infrared spectroscopy also confirmed the interaction between MSP-PPV anionic polyelectrolyte and the sheets of zinc-layered hydroxide matrix. In addition, in order to better understand the photoluminescent behavior, a complete characterization of optical properties of the MSP-PPV/ZHL hybrids was also performed. Due to the MPS-PPV presence, all hybrid materials showed absorption bands in the visible region (≈450 m) with emission band in the green region (≈560 m). Moreover, the photophysical properties of the MSP-PPV intercalated/exfoliated can be easily tuned by changing their concentration demonstrating that the zinc-layered hydroxide material plays an important role in preventing the aggregation and photostability of the anionic polyelectrolyte.