Detection of low-content water in organic solvents is highly desirable for a number of chemical industries. However, most of luminescence water detectors reported so far easily generate liquid waste and the luminescence intensity of single emissive transition is susceptible by many factors. Herein a simple and green solid-state detecting way is proposed to achieve the ratiometric detection of low-level water in organic solvents based on Eu³⁺, Tb³⁺, and acac co-doped Laponite (abbreviated as Eu₁Tb₉(acac)_n@Lap). Such a luminescence detector represents excellent fingerprint correlation between water content in solvents and emission intensity ratio (I_Eu/I_Tb), and the variable emissive light colors of Eu₁Tb₉(acac)_n@Lap is observed as water concentration in common organic solvents (MeCN, EtOH, and THF) increases (0%–5% v/v) clearly and directly with the naked eye. The approach should be a very promising strategy to achieve the low-content water detecting in organic solvents.

Water-soluble hybrid composites with great potential for selective and sensitive sensing and that are obtained through simple, rapid, and environmentally friendly methods are highly desirable and remain a challenging task. Herein, we present luminescent hybrid composites that were realized by linking Na₃[Ln(dpa)₃] (dpa=2,6-pyridinedicarboxylic acid) to octa-amino functionalized polyhedral oligomeric silsesquioxane (POSS-NH₂) through hydrogen-bonding interactions between the oxygen atoms of the carboxylate groups of dpa and the hydrogen-bond-donor amino groups. The resulting hybrid composites Ln(dpa)₃@POSS-NH₂ are highly soluble in aqueous solutions and the quantum yield of Eu(dpa)₃@POSS-NH₂ is as high as 56.5 % or 46.3 % in the solid state and in aqueous solution, respectively, as determined by using the integrating sphere method. The novel water-soluble luminescent hybrid composites exhibit high thermal and photostability, and the emitted colors of the resulting hybrid composite can be finely tuned by changing the Eu³⁺/Tb³⁺ ratio. Interestingly, Eu(dpa)₃@POSS-NH₂ hybrid composites exhibited an effective switch-off fluorescence response to Cu²⁺ over other common metal ions in aqueous media.

Herein, we report the fabrication of a sensitive ratiometric and colorimetric luminescent thermometer with a wide operating-temperature range, from cryogenic temperatures up to high temperatures, through the combination of lanthanide and transition metal complexes. Benefiting from the transition metal complex as a self-reference, the lanthanide content in the mixed-coordination complex, Eu_0.05(Mebip-mim bromine)_0.15Zn_0.95(Mebip-mim bromine)_1.9, was lowered to 5 %.

A new poly(ionic liquid) (Terpy-PIL) carrying a terpyridine group in each repeating unit of the polymer architecture was readily prepared by polymerization of the monomer (Terpy-IL), which was initiated by azobis(isobutyronitrile) (AIBN). The obtained poly(ionic liquid) can coordinate and sensitize europium(III) ions through numerous chelating terpyridine moieties, which are linked to the polymer chains. A red-emitting luminescent material was obtained by the complexation of europium(III) salts with Terpy-PIL, and the luminescence is due to an energy transfer from the terpyridine moieties to Eu³⁺ ions. The luminescence performance of the luminescent material based on Terpy-PIL, for example the ⁵D₀ quantum efficiency and the decay time, is much higher than that of the luminescent material prepared from the monomer Terpy-IL, which can be ascribed to the confinement of the europium(III)–terpyridine complexes to the polymer architecture.

Stopper molecules attached to nanozeolite L (NZL) boost the luminescence of confined Eu³⁺-β-diketonate complexes. The mechanism that is responsible was elucidated by comparing two diketonate ligands of different pK_a and two aromatic imines, and by applying stationary and time resolved spectroscopy. The result is that the presence of the imidazolium based stopper is favorable to the sustainable formation of Eu³⁺-β-diketonate complexes with high coordination by decreasing the proton strength inside the channels of NZL. A consequence is that strongly luminescent transparent films can be prepared using aqueous suspension of the stopper modified composites.

The first europium(III) β-diketonate complex functionalized polyhedral oligomeric silsesquioxane (POSS) has been obtained by immobilization of such a complex at a silicon vertex of the POSS cage through the complexation of Eu³⁺ ions with thenoyltrifluoroacetone-functionalized POSS. The new molecular hybrid material is liquid at room temperature, and shows bright-red emission when irradiated with UV light due to energy transfer from the thenoyltrifluoroacetone ligand to the coordinated Eu³⁺ ions. Thermal analysis has revealed a significant improvement in the thermal stability of the material compared with tris(2-thenoyltrifluoroacetonate)europium(III) dihydrate, [Eu(TTA)₃]⋅2 H₂O. In the context of recent advances in printable electronic technology, this novel luminescent organic liquid with the characteristic emission of Eu³⁺ may potentially be useful in the development of next-generation organic devices such as flexible displays.

The spectroscopic behavior of ionic Eu³⁺ or Tb³⁺ complexes of an aromatic carboxyl-functionalized organic salt as well as those of the hybrid materials derived from adsorption of the ionic complexes on Laponite clay are reported. X-ray diffraction (XRD) patterns suggest that the complexes are mainly adsorbed on the outer surfaces of the Laponite disks rather than intercalated within the interlayer spaces. Photophysical data showed that the energy-transfer efficiency from the ligand to Eu³⁺ ions in the hybrid material is increased remarkably with respect to the corresponding ionic complex. The hybrid material containing the Eu³⁺ complex shows bright red emission from the prominent ⁵D₀⁷F₂ transition of Eu³⁺ ions, and that containing the Tb³⁺ complex exhibits bright green emission due to the dominant ⁵D₄⁷F₅ transition of Tb³⁺ ions.

Stopper molecules attached to nanozeolite L (NZL) boost the luminescence of confined Eu³⁺-β-diketonate complexes. The mechanism that is responsible was elucidated by comparing two diketonate ligands of different pK_a and two aromatic imines, and by applying stationary and time resolved spectroscopy. The result is that the presence of the imidazolium based stopper is favorable to the sustainable formation of Eu³⁺-β-diketonate complexes with high coordination by decreasing the proton strength inside the channels of NZL. A consequence is that strongly luminescent transparent films can be prepared using aqueous suspension of the stopper modified composites.

Herein, we report a facile method to prepare thermally reversible, flexible, transparent, and luminescent ionic organosilica gels with tunable emission colors. The reaction of an amino-functionalized ionic liquid ([NH₂-Bim]Br) with 3-(triethoxysilyl)propyl isocyanate results in an ionic-liquid-modified alkoxysilane, the hydrolysis and condensation of which lead to thermally reversible, flexible, and luminescent ionic gels in the presence of lanthanide species. The luminescence color can be fine-tuned by changing the Ln³⁺ ions (Eu³⁺, Tb³⁺, or a mixture of Eu³⁺ and Tb³⁺) and by changing the excitation wavelength. The absolute quantum yields of the flexible luminescent gels with europium(III) and terbium(III) complexes are determined to be 15 and 21 %, respectively, by using an integrating sphere. The thermal reversibility of the organosilicas makes them attractive for the development of flexible optical devices and flexible luminescent devices such as organic light-emitting diodes (OLEDs).

The acidity of europium(III)-exchanged zeolite L (Eu³⁺/ZL) and its influence on the luminescence performances of encapsulated europium(III) β-diketonate complexes are reported. The results indicate the importance of understanding the acidity of Eu³⁺/ZL in the preparation of luminescent host–guest materials of zeolite L crystals and europium(III) β-diketonate complexes. The acidity of Eu³⁺/ZL was determined roughly by using a dye (thionine) as the probe molecule. The luminescence performances of the host–guest materials, including excitation and emission spectra, lifetime of Eu³⁺ ions, quantum yield, and energy transfer efficiency, have been investigated. The luminescence behavior of the host–guest materials can be tuned by changing the acidity inside the channels of the zeolite L crystals and can potentially be used as a sensor for detecting ammonia.

Herein we report the synthesis of propanoic acid functionalized ionic liquids (ILs) with various lengths of alkyl chain on the imidazole ring. The synthesized propanoic acid functionalized ILs were used to dissolve Eu₂O₃ (or Tb₄O₇) due to the formation of europium(III) (or terbium(III)) carboxylate, aimed to get soft luminescent materials combining the properties of ILs and attractive luminescent properties of lanthanide ions. The luminescent behavior of Eu³⁺ and Tb³⁺ in the ILs were investigated by luminescence spectroscopy. The affect of the alkyl chain on the luminescent behavior (the asymmetry parameter (R), the lifetime of ⁵D₀, and the ⁵D₀ quantum efficiency) of Eu³⁺ has been discussed.

We discuss artificial photonic antenna systems that are built by incorporating chromophores into one-dimensional nanochannel materials and by organizing the latter in specific ways. Zeolite L (ZL) is an excellent host for the supramolecular organization of different kinds of molecules and complexes. The range of possibilities for filling its one-dimensional channels with suitable guests has been shown to be much larger than one might expect. Geometrical constraints imposed by the host structure lead to supramolecular organization of the guests in the channels. The arrangement of dyes inside the ZL channels is what we call the first stage of organization. It allows light harvesting within the volume of a dye-loaded ZL crystal and also the radiationless transport of energy to either the channel ends or center. One-dimensional FRET transport can be realized in these guest–host materials. The second stage of organization is realized by coupling either an external acceptor or donor stopcock fluorophore at the ends of the ZL channels, which can then trap or inject electronic excitation energy. The third stage of organization is obtained by interfacing the material to an external device via a stopcock intermediate. A possibility to achieve higher levels of organization is by controlled assembly of the host into ordered structures and preparation of monodirectional materials. The usually strong light scattering of ZL can be suppressed by refractive-index matching and avoidance of microphase separation in hybrid polymer/dye–ZL materials. The concepts are illustrated and discussed in detail on a bidirectional dye antenna system. Experimental results of two materials with a donor-to-acceptor ratio of 33:1 and 52:1, respectively, and a three-dye system illustrate the validity and challenges of this approach for synthesizing dye–nanochannel hybrid materials for light harvesting, transport, and trapping.

We report here on the preparation of novel luminescent core-shell material by initial coating with polyelectrolytes and subsequent with a silica shell on the lanthanide complexes loaded zeolite L microcrystals. Lanthanide complexes loaded zeolite L was prepared by insertion of 2-thenoyltrifluoroacetone (TTA) into the nanochannels of zeolite crystals by gas diffusion of TTA to Eu³⁺ exchanged zeolite L, coating a silica shell on the lanthanide complexes loaded zeolite L resulted to the novel luminescent core-shell material. The luminescent core-shell material was further functionalized with silylated terbium(III) complex and the obtained material was used as the luminescence sensing of dipicolinic acid (DPA), which is a major constituent of many pathogenic spore-forming bacteria.

A urea-based bis-silylated bipyridine ligand derived from 4,4′-diamino-2,2′-bipyridine has been prepared. Organic–inorganic hybrid materials with a high loading of lanthanide 2,2-bipyridine moieties were obtained by using the silylated bipyridine as the only siloxane network precursor in the presence of lanthanide ions (or lanthanide complexes). The in-situ formation of lanthanide complexes from lanthanide ions and the silylated bipyridine during the sol–gel processing was confirmed by the luminescence behavior of the obtained hybrid materials and that of the corresponding pure lanthanide complex [Ln(bpy)₂Cl₃·2H₂O]. Tris(2-thenoyltrifluoroacetonato)europium(III) dihydrate complexes were coupled to the hybrid materials via adduct formation with the nitrogen atoms from bis-silylated bipyridine, and the coordinated water molecules were expelled from the first coordination sphere of the lanthanide(III) ion as revealed by the much longer lifetime of the hybrid material compared with that of the pure tris(2-thenoyltrifluoroacetonato)europium(III). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Luminescent lanthanide-complex-bridged polysilsesquioxanes were prepared by sol–gel processing of a monomer with a large heterocyclic bridging group in the presence of lanthanide ions under acidic conditions. SEM, XRD, FTIR, luminescence spectra and luminescence decay analysis were used to characterize the obtained materials. The ⁵D₀ quantum efficiency and the number of the water molecules coordinated to the Eu³⁺ ion were theoretically estimated on the basis of emission spectra and the lifetime of the ⁵D₀ state.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)