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Excitation dependent luminescent materials, which have attracted significant scientific attention in the field of information security owing to information storage and luminescence properties. However, it remains a formidable challenge in developing excitation dependent luminescent materials with a simple synthesis method and predictably modulated luminescent outputs. Herein, a novel Ln3+/Fluorescent dyes@MOFs strategy is developed to generate excitation dependent continuous color-changing luminescent materials via a hydrothermal method and post-synthetic modification (PSM), based on metal-organic frameworks (MOFs) matrix doped with lanthanide cations and fluorescent dyes encapsulated into the lanthanide MOFs. The continuous proportional emission of mixed luminescence appeared within a single matrix in response to the different excitation wavelength and the proportional emission control (PEC) mechanism between the two luminescent centers is proposed. In addition, the photoluminescence platform demonstrates a distinct security method based on covert color that are controlled by distinct excitation wavelengths and excellent luminescence stability have also been verified in these new materials. • Ln3+/Hoc@UIO-66(DPA) achieve excitation wavelength-dependent continuous color-tunable luminescence in a single mixture. • Proportional emission control (PEC) mechanism is proposed. • Ln3+/Hoc@UIO-66(DPA) (Ln = Eu, Tb) materials have potential applications in the field of anticounterfeiting. • The materials are acid and alkali resistant, have high thermal stability, and can be multi-functional luminescent. [ABSTRACT FROM AUTHOR]

A novel precursor PMA–Si was synthesized by modifying 1,2,4,5-benzene-tetracarboxylic acid (PMA) with 3-aminopropyltriethoxysilane (APTES). Then the hybrids were prepared by PMA–Si coordinating to lanthanide ions (Eu 3+ and Tb 3+ ) in sol–gel process. In order to improve luminescent efficiency, 1,10-Phenanthroline (Phen) was introduced to the system as the second ligand. As-prepared compounds in sol condition were coated on quartz plates to form a layer of thin film, which was different from other similar hybrids. The properties of the hybrids were characterized by FT-IR, fluorescence spectra, TG and SEM. The results showed that the obtained materials enhanced thermal stability, mechanical resistances, waterproofness as well as machining properties. [ABSTRACT FROM AUTHOR]

In this paper, a graphene oxide/rare-earth complexes hybrid material without 1,10-Phenanthroline based on 4′-paraphenyl-carboxyl-2,2':6′,2″-terpyridine (Hcptpy) as ligand, graphene oxide sheets (GOSs) as inorganic matrix and europium ion as luminescence center has been synthesized via non-covalent approach between GOSs and Hcptpy. This obtained hybrid material exhibits stronger luminescence intensity, better thermal stability and longer decay lifetime than pure Eu3+ complexes. Moreover, a transparent and strongly luminescent thin film also is prepared by self-assembly at room temperature. This thin film shows great potential applications in the area of optics. • A GOSs/rare-earth complexes hybrid material was synthesized without Phen. • The obtained hybrid material exhibits better performance than pure Eu3+ complexes. • A polymer film was synthesized by self-assembly of Eu-Hcptpy/GOSs and PMMA. • The obtained film has excellent transmittance and luminescent properties. [ABSTRACT FROM AUTHOR]

Luminescent dye molecules have attracted enormous research interest, whereas, there are inherent drawbacks that limit their utilization across a broad variety of fields. Herein, a novel dual-luminescent carboxylic acid functionalization Eu3+/Hoc@UIO-66(H 3 BTC) (Hoc = 7-hydroxycoumarin) was prepared by introducing luminescent dye molecules (Hoc) into the UiO-66-type dual-ligand metal−organic frameworks (MOFs) utilize the encapsulation approach and postsynthetic modification (PSM). UIO-66(H 3 BTC) was constructed using 1,4-dicarboxybenzene (TPA) as the first ligand, which can restrict the aggregation-induced quenching of Hoc dyes and maintains the Hoc dyes stably included after preparation. 1,3,5-benzenetricar boxylic acid (H 3 BTC) was used as a second ligand to sensitize Eu3+ ions for the antenna effect emission and provide detection sites. Eu3+/Hoc@UIO-66(H 3 BTC) material possesses blue luminescence from Hoc molecules as well as red luminescence from Eu3+ when irradiated by UV lamp, which can be used for ratiometric luminescence detection of Cu2+/Fe3+ through reference to the intensity ratios of two emitting peaks. Eu3+/Hoc@MOFs(H 3 BTC) as a luminescence sensor, displays an ultrahigh sensitivity (Cu2+:4.58 μM, Fe3+:18 μM), strong ant-interference ability, and fast response for detecting analytes. This project demonstrates that the dual-ligand Zr-based MOFs and luminescence dyes offers a novel ratiometric luminescence detection platform for heavy metal ions visible identification. • MOFs includes free –COOH groups that can sensitize Eu3+ ions to realize luminescence and provide site-specific assays. • Eu3+/Hoc@UIO-66(H 3 BTC) overcome (ACQ) effects to encapsulate Hoc dye molecule luminescence. • The advantages of dye encapsulation for detection are proven, with dual emission improving sensitivity. • The ratiometric sensor possess a wide linear concentration range, low LOD and visible detection. [ABSTRACT FROM AUTHOR]

Abstract: In this work, we report the uniformly microsized luminescent materials prepared by a solid state reaction of WO3 and Ln3+-exchanged zeolite L at 700°C. The obtained materials were investigated by SEM, XRD and photoluminescence spectroscopy. The influence of tungstate-oxygen species on the morphology and luminescence of the materials were discussed in detail. Energy transfer from the tungstate-oxygen species to Eu3+ and Tb3+ ions have been demonstrated by the photoluminescence spectra, implying the loading of tungstate-oxygen species into the nanochannels of the crystals and the close proximity of which to Eu3+ ions. [Copyright &y& Elsevier]

• The NaYF 4 :Ln/NaYF 4 :Eu composite possesses up-conversion and down-shifting luminescence properties. • The composite possesses excellent compatibility and fluorescence purity. • They can be prepared into fluorescent patterns and provide a potentiality for anti-counterfeiting. Herein, a series of novel dual-mode NaYF 4 :Ln/NaYF 4 :Eu (Ln = Yb, Er, Tm) composites involving up-conversion and down-shifting luminescence have been prepared by a facile synthetic method. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray analysis, up-conversion and down-shifting fluorescence spectrometer were used to characterize the materials. By doping different lanthanide ions and tailoring the molar ratio of the doped lanthanide ions, three kinds of composites were obtained which could exhibit three-primary-color (red-green-blue, abbreviating as RGB) up-conversion luminescence under the irradiation of 980 nm laser, and generate red down-shifting color under the excitation of 393 nm. The composites show excellent photoluminescence properties, which attribute to NaYF 4 served as a major matrix for both the up-conversion and down-shifting materials. Moreover, the work provides a promising material for anti-counterfeiting application. [ABSTRACT FROM AUTHOR]