Local Structure and Near-Infrared Emission Features of Neodymium-Based Amine Functionalized Organic/Inorganic Hybrids

Absorption- and Excitation-Modulated Luminescence of Pr3+, Nd3+, and Lu3+ Compounds with Dianions of Tetrafluoroterephthalic and Camphoric Acids

The luminescence of coordination polymers of Pr³⁺, Nd³⁺, and Lu³⁺ with tetrafluoroterephthalate and camphorate, [Ln₂(Fbdc)₃(DMF)₂(H₂O)]₂ (Ln = Pr, Nd, Lu) and [Ln₂(Camph)₂(NO₃)₂(MeOH)]₄ (Ln = Pr, Nd, Lu), was studied. Ligand-centered and/or metal-centered emissions appear, which depend on the excitation wavelength, ultimately allowing the emitted light color to be adjusted. Low-efficiency ligand-to-metal energy transfer leads to a difference between the excitation spectra of the tetrafluoroterephthalate- and camphorate-Pr³⁺ compounds, arising from a primary filtering effect on the ligand-centered excitation, by Pr³⁺ absorption. A secondary inner filter effect significantly changes the shape of the luminescence band, allowing a wide variation in the emission color, producing, for instance, a purple color, which is not the normal spectral emission. The low-efficiency energy transfer renders tetrafluoroterephthalate and camphorate ineffective as traditional "antenna" ligands for Pr³⁺ and Nd³⁺.

Flexible Optical Amplifier for Visible-Light Communications Based on Organic-Inorganic Hybrids

Visible-light communications (VLCs) based on white light-emitting diodes (LEDs) are emerging as a low-cost and energy-efficient alternative solution to wireless communications. As white emitting LEDs use a combination of a long-lived yellow emission combined with the faster response of a blue emitting LED (∼460 nm), VLC technology requires amplification of the blue component to improve the signal-to-noise ratio. We report the fabrication and characterization of planar and channel waveguides based on a blue-emitting polyfluorene conjugated polyelectrolyte, namely, poly[9,9-bis(4-sulfonylbutoxyphenyl)fluorene-2,7-diyl-alt-1,4-phenylene] (PBS-PFP) incorporated into diureasil organic-inorganic hybrids for optical amplification in VLC. Taking advantage of the diureasil host as a UV self-patternable material, direct UV laser writing was used to pattern channel waveguides with a larger refractive index (Δn=0.09) compared to the nonexposed region, enabling confinement and guidance of the PBS-PFP emission with a maximum optical gain efficiency value of 1.62 ± 0.02 cm μJ^-1. This value is among the best figures of merit known for polymeric materials with additional advantages added by the diureasil hybrid host, namely, mechanical flexibility, thermal stability, and low insertion losses due to the nearly null refractive index contrast between the optical fiber and the amplification device, establishing the proposed approach as a promising cost-effective solution for optical amplification in VLCs.

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.

On the structure of high performance anticorrosive PMMA–siloxane–silica hybrid coatings

Environmentally compliant organic–inorganic hybrid coatings for efficient corrosion protection of metallic surfaces are potential alternatives to the current method based on chromate passivation.

Multi-component assembly and luminescence tuning of lanthanide hybrids based with both zeolite L/A and SBA-15 through two organically grafted linkers

Novel luminescent micro–mesoporous multi-component lanthanide hybrid materials are prepared by assembling both functionalized zeolite A/L and modified SBA-15 through two organically grafted silane linkers.

Highly transparent and luminescent lanthanide ion-containing bridged polysilsesquioxanes

Novel luminescent bridged polysilsesquioxane monoliths of high transparency have been obtained by hydrolysis and condensation of the precursor under acidic conditions. The monoliths were characterized by FTIR spectroscopy, photoluminescence spectroscopy, and SEM, and they have been used as hosts of Eu(3+), Tb(3+) and Nd(3+) ions. The luminescence lifetime of Tb(3+) in this host was 2.1 ms. The interaction between the host and the lanthanide ions could be confirmed by FTIR spectra. The number of water molecules coordinated to the Eu(3+) ions was determined to be one. Incorporation of Nd(3+) as guest resulted in NIR-luminescent materials.

Synthesis and structural characterization of cationic 5-hydroxy-1,3-diketonate stabilized dinuclear complexes and tetranuclear lanthanoid clusters

5-Hydroxy-1,3-diketonate ligands have been found to stabilize dimeric complexes and tetrameric lanthanoid clusters dependent on the degree of steric bulk provided by the presence or absence of a methoxy group. Treatment of (R/S,Z)-1'-hydroxy-3-(hydroxy(phenyl)methylene)bi(cyclopentan)-2-one (Hhpb) and the p-methoxyphenyl derivative (Hhmb) with [LnCl(2)(H(2)O)(6)]Cl yields clusters of composition [Ln(4)(Cl)(2)(O)(hpb)(6)]Cl(2) (Ln = Nd (1), Ho (2), Tb (3), and Er (4)) and [Ln(2)(hmb)(5)]Cl (Ln = La (5), Nd (6), Tb (7), Dy (8), and Er (9)). Single crystal X-ray analysis of the tetranuclear cluster has revealed the lanthanoid core to be in a tetrahedral arrangement around a central mu(4)-oxygen, bridged by symmetrical chlorides and shrouded in six bridging hpb ligands. The dimeric complexes are stabilized by three bridging and two terminal hmb ligands. In each instance, double or single cationic charges respectively are balanced by chloride anions.

Lanthanide-containing light-emitting organic-inorganic hybrids: a bet on the future

Interest in lanthanide-containing organic-inorganic hybrids has grown considerably during the last decade, with the concomitant fabrication of materials with tunable attributes offering modulated properties. The potential of these materials relies on exploiting the synergy between the intrinsic characteristics of sol-gel derived hosts (highly controlled purity, versatile shaping and patterning, excellent optical quality, easy control of the refractive index, photosensitivity, encapsulation of large amounts of isolated emitting centers protected by the host) and the luminescence features of trivalent lanthanide ions (high luminescence quantum yield, narrow bandwidth, long-lived emission, large Stokes shifts, ligand-dependent luminescence sensitization). Promising applications may be envisaged, such as light-emitting devices, active waveguides in the visible and near-IR spectral regions, active coatings, and bio-medical actuators and sensors, opening up exciting directions in materials science and related technologies with significant implications in the integration, miniaturization, and multifunctionalization of devices. This review provides an overview of the latest advances in Ln(3+)-containing siloxane-based hybrids, with emphasis on the different possible synthetic strategies, photoluminescence features, empirical determination.

Optical Properties of Lanthanide-Doped Lamellar Nanohybrids

In this article a detailed study of the optical properties of lanthanide doped lamellar nanohybrids synthesized by the "benzyl alcohol route" is presented. The synthetic approach results in the formation of a highly ordered lamellar nanocomposite consisting of yttrium or gadolinium oxide crystalline layers with a confined thickness of about 0.6 nm, separated from each other by organic layers of intercalated benzoate molecules. When the inorganic layers are doped with optically-active lanthanide ions they show outstanding emission properties in the green (Tb(3+)), red (Eu(3+)) and near infrared (Nd(3+)). The local environment of the emitting ions and the energy transfer processes involving the phenyl ring of the benzoate complexes and the lanthanide ions are presented, as well as radiance and lifetime measurements. The radiance values are comparable and in some cases even larger than those of standard phosphors, proving that these nanohybrids can compete, from an emission efficiency point of view, with commercial phosphors. Furthermore, in these nanohybrids it is possible by simply changing the excitation wavelength, to tune the emission colour chromaticity without loosing the radiance.