Mesoporous Silica Nanoparticles-Embedded Lanthanide Organic Polyhedra for Enhanced Stability, Luminescence and Cell Imaging

We report here a simple but efficient “ship-in-a-bottle” synthetic strategy for increasing the stability and luminescence performance of LOPs by embedding them into mesoporous silica nanoparticles (MSNs). Three types of...

Two homochiral EuIII and SmIII enantiomeric pairs showing circularly polarized luminescence, photoluminescence and triboluminescence

Two homochiral EuIII and SmIII tris(β-diketonate) enantiomeric pairs, based on fluorinated β-diketone (Hbtfa) and enantiopure asymmetric N,N'-donor ligands (LR and LS), Λ-Eu(btfa)3LR (R-1-Eu)/Δ-Eu(btfa)3LS (S-1-Eu) and Λ-Sm(btfa)3LR (R-2-Sm)/Δ-Sm(btfa)3LS (S-2-Sm) (btfa- = 4,4,4-trifluoro-1-phenyl-1,3-butanedionate and LR/LS = (-)/(+)-4,5-pineno-2,2'-bipyridine) were synthesized. The electronic circular dichroism (ECD) spectra confirmed their enantiomeric nature. R-1-Eu/S-1-Eu and R-2-Sm/S-2-Sm exhibit intense characteristic emissions of EuIII (red) and SmIII (orange-red) ions both in the solid state and in DCM with long lifetimes and high luminescence quantum yields. For example, the overall quantum yields reach up to 61% and 53% along with very high sensitization efficiency values of 82 and 79 for R-1-Eu in the solid state and in DCM, respectively. Notably, the corresponding values are determined to be 6.5% (solid state) and 3.1% (DCM) for R-2-Sm, which are among the highest quantum yields for rare SmIII tris(β-diketonate) luminescent complexes reported to date. Furthermore, R-1-Eu and R-2-Sm show a strong triboluminescence (TL) phenomenon visible with the naked eye in daylight. Moreover, R-1-Eu/S-1-Eu and R-2-Sm/S-2-Sm show circularly polarized luminescence (CPL) properties. Particularly, the luminescence dissymmetry factors (glum) for R-2-Sm/S-2-Sm are larger than those for R-1-Eu/S-1-Eu despite the fact that SmIII complexes usually show poorer emission than EuIII homologues, which is very rare in the reported EuIII and SmIII CPL-active complexes.

Luminescent Vesicles and Lyotropic Liquid Crystals in Ethylammonium Nitrate from a Partially Amphiphilic Eu Complex

Soft luminescent materials have attracted much attention because of their self-assembled and controllable properties. To explore their facile and effective fabrication ways, we report here the self-assembling of luminescent vesicles and lyotropic liquid crystals (LLCs) in a protic ionic liquid, ethylammonium nitrate, by a partially amphiphilic europium β-diketonate complex (Eu(III)) with a 1-dodecyl-3-methylimidazolium cation as the counter ion. An interesting result came from the complex-induced vesicle formation of corresponding amphiphile, 1-dodecyl-3-methylimidazolium bromide ([C₁₂mim]Br), which has been rarely reported in the past. It was the interaction between the Eu(III) and imidazolium group that changed the critical packing parameter of [C₁₂mim]Br, which finally resulted in the occurrence of vesicles. The obtained vesicle aggregates exhibited enhanced fluorescence intensity and lifetime compared to those of Eu(III) solution. Meanwhile, a hexagonal LLC phase with better fluorescence properties was found at higher [C₁₂mim]Br concentration. The obtained photophysical data confirmed that the order degree of Eu(III)-containing aggregates could effectively increase the energy transition efficiency of ligands. The better luminescent properties of LLC resulted from the stronger stabilizing and binding effects on Eu(III) in LLC than that in vesicles, which might be caused by closer molecular packing in LLC. The results presented here will not only expand the strategy of constructing lanthanide-containing luminescent soft materials in ionic liquids but also provide reference to better understand the effect of organized aggregates on luminescence properties.

Luminescent materials of lanthanoid complexes hosted in zeolites

Our emphasis is on understanding the influence of microenvironments of the void spaces on the luminescence performances of the encapsulated lanthanide complexes.

"Rigid" Luminescent Soft Materials: Europium-Containing Lyotropic Liquid Crystals Based on Polyoxyethylene Phytosterols and Ionic Liquids

Soft materials of europium β-diketonate complexes constructed in lyotropic liquid crystals (LLCs) mediated by ionic liquids (ILs) are impressive for their excellent luminescence performance and stability. For the aim to further improve their mechanical processability and luminescent tunablility, the polyoxyethylene phytosterols (BPS-n) were introduced here as structure directing agents to prepare relatively "rigid" lamellar luminescent LLCs in 1-butyl-3-methyl-imidazolium hexafluorophosphate by doping europium β-diketonate complexes with different imidazolium counterions. As a result of the solvophobic sterol ring structure of BPS-n, the more effective isolation and confinement effects of europium complexes could be achieved. The longest fluorescence lifetime and the highest quantum efficiency reported so far for europium containing lyotropic organized soft materials were thus obtained. Changing the molecular structures of BPS-n with different oxyethylene chains or doped complexes with imidazolium counterions of different alkyl chain lengths, the spacings of lamellar LLC matrixes and position of dispersed complexes became tunable. The measured luminescent and rheological properties for such composite LLCs showed a dependence on the rigidity and isolation capability afforded by sterol molecules. It was also found that the increase of counterion alkyl chain length would weaken the LLC matrix's confinement and isolation effects and therefore exhibit the deteriorated luminescence performance. The enhanced luminescence efficiency and stability of doped BPS-n LLCs reflected the excellent segregation of europium complexes from each other and therefore the reduced self-quenching process. The obtained results here present the designability of LLC matrixes and their great potential to promote achieving the luminescence tunability of soft materials.

Solvent free mechanochemical synthesis of Eu3+ complex and its luminescent sensing of trace water and temperature

A solid state Eu(iii) complex was synthesized by a mechanochemical method and used for luminescent sensing of trace water and temperature.

Temperature-dependent luminescence properties of lanthanide(III) β-diketonate complex-doped LAPONITE®

In this work, by doping the lanthanide(III)-hexafluoroacetylacetone complex into LAPONITE®, we obtained a lanthanide-based organic-inorganic hybrid material. The resulting hybrid materials were fully characterized with elementary analysis, scanning electron microscopy (SEM) and powder X-ray diffraction (PXRD) techniques. The Ln(3+) and HFA loadings were experimentally determined to be roughly 0.3 per u.c. and 0.72 per u.c. by analyzing the supernatant (titration against EDTA) and elemental analysis, respectively. XRD patterns suggest that at least partial complexes are intercalated within the interlayers of the LAPONITE®. The in situ formation of luminescent Ln(3+) complexes is confirmed by the luminescence data. Furthermore, the emission intensity ratio of the (5)D4→(7)F5 transition (Tb(3+)) to the (5)D0→(7)F2 transition (Eu(3+)) of the hybrid material containing both Eu(3+) and Tb(3+) can be linearly related to temperature in the range from 197 K to 287 K (temperature sensitivity: 1.107% per K), which will be an appealing alternative for in situ and real time detection of temperature in many special areas. This strategy presents new opportunities for the development of highly sensitive and stable thermo sensors.

A paper-based lanthanide smart device for acid–base vapour detection, anti-counterfeiting and logic operations

A paper-based lanthanide smart device was designed for naked-eye detection of acid–base vapors with quick response and good reversibility; the applications of this device were also expanded to anti-counterfeiting and logic operations.

Lanthanide complex inside–outside double functionalized zeolite A hybrid materials for luminescence sensing

Double functionalization assembled hybrids exhibit luminescence in the visible/NIR region and among which [DBM-Yb-ZA]–NTASi-Eu shows high sensing selectivity for Fe³⁺.

Luminescent europium(III)-β-diketonate complexes hosted in nanozeolite L as turn-on sensors for detecting basic molecules

The luminescence efficiency of Eu(3+)-β-diketonate complexes entrapped within the channels of nanozeolite L is severely decreased by the acidic environment in the channels. The neutralization of the acid sites can remarkably increase the luminescence efficiency due to the formation of complexes with high coordination numbers. Herein we report a simple, effective and robust luminescent sensor for detecting basic molecules (such as amines) based on the above observations.

Luminescence enhancement after adding organic salts to nanohybrid under aqueous condition

Lanthanide-based organic-inorganic hybrid materials (LnOIH) are of immense importance for various applications nowadays, while it still remains a significant challenge to achieve high luminescence efficiency in aqueous environment. Herein we present a simple and environmentally friendly two-step strategy to prepare strongly red-light emitting nano-LnOIH by first in situ forming Eu(3+)-β-dikeonate complexes on Laponite platelets and subsequently increasing the coordination number of the complexes via the modification with a silane-functionalized imidazolium salt, which can fully protect Eu(3+) ions from the water molecule quenching. The mechanism of how the imidazolium salt favors the formation of Eu(3+)-β-dikeonate complex with large coordination number was elucidated. The result is that the removal of the abundant protons on the Laponite platelets through a mechanism of synergic effect of ion exchange and neutralization drives the formation of Eu(3+)-β-diketonate complexes with high coordination number. The high efficiency of the resulting luminescent nano-LnOIH in water endows the nanohybrid with good aqueous solution processability and opens the possibility of using them under complicated aqueous conditions for biorelated applications.

Aqueous synthesis of stable and luminescent flexible non-covalently assembled europium(iii) complexes–organoclay films

Flexible, transparent and red-light-emitting luminescent polymer thin film derived from Eu(TTA)₃-doped hydrophilic hybrid material.

Enhanced energy transfer efficiency and stability of europium β-diketonate complex in ionic liquid-based lyotropic liquid crystals

The self-assembly of luminescent lyotropic liquid crystals with europium β-diketonate complex confined within via hydrogen bonds between P123 and imidazolium cations is demonstrated.

Luminescent hybrid materials based on zeolite L crystals and lanthanide complexes: host-guest assembly and ultraviolet-visible excitation

Several kinds of host-guest hybrid materials have been synthesized employing a ship in a bottle method by loading 9-hydroxy-2-methylphenalenone (MHPO) or 9-hydroxyphenalen (HPNP) from gas phase into the nanochannels of Ln(3+)-exchanged zeolite L (ZL) crystals (Ln=Gd or Eu). The resulting hybrids without lanthanide ions, MHPO-ZL, HPNP-ZL and the hybrids with lanthanide ions Ln-MHPO-ZL and Ln-HPNP-ZL are characterized with FT-IR, UV-vis DRS and photoluminescence spectroscopy. The photoluminescence properties of these hybrid materials have been analyzed and discussed, exhibiting the luminescence of Eu(3+) and ligands under the excitation at ultraviolet-visible region. These results provide useful data and can be expected to have potential application in the practical fields.

Color-tunable luminescence of organoclay-based hybrid materials showing potential applications in white LED and thermosensors

Hybrid composites with great potential for white light LED and temperature sensing obtained through a simple, low cost, and environmental benign way is highly desirable and remains a challengeable task. Herein we present luminescent hybrid composites both in the form of powder and transparent film by simply mixing organic sensitizer, aminoclay (AC), and lanthanide (Ln(3+)) in aqueous solution, the emission color of which can be fine-tuned by changing various parameters such as the molar ratio of Eu(3+) to Tb(3+), excitation wavelength, and the temperature. White lights with satisfied color coordinates have been achieved. The emission intensity ratio of (5)D4 → (7)F5 transition (Tb(3+)) to (5)D0 → (7)F2 transition (Eu(3+)) of the composite containing both Eu(3+) and Tb(3+) can be linearly related to temperature in the range from 78 K to 288 K. These characteristics make the composites suitable for optoelectronic devices such as thermosensors and white light LED.

Luminescent materials of zeolite functionalized with lanthanides

Luminescent materials based on the functionalization of zeolite with lanthanide constitute an intense research topic since they combine the attractive properties of zeolite and unique optical properties of Ln³⁺ ions. This review highlights the utilization of zeolite as luminescent materials showing tunable luminescence performance, well-organized structures and useful host–guest interactions.

Novel luminescent hybrids prepared by incorporating a rare earth ternary complex into CdS QD loaded zeolite Y crystals through coordination reaction

Novel luminescent hybrids were assembled by incorporating a rare earth (Eu, Tb), mercaptan acid and 1,10-phenanthroline ternary complex into CdS loaded zeolite Y through coordination reaction.