Design of luminescent lanthanide complexes: From molecules to highly efficient photo-emitting materials

Folic acid-conjugated europium complexes as luminescent probes for selective targeting of cancer cells

We report the synthesis of three optical probes (Eu(3+)⊂1, Eu(3+)⊂2, and Eu(3+)⊂3) having a luminescent Eu complex (signaling unit) bonded in different positions to folic acid (FA), the folate receptor (FR) targeting unit. The structures of the two regioisomers Eu(3+)⊂1 and Eu(3+)⊂2 were assigned by mass spectrometric experiments. The optical properties and stability of these probes were assessed in phosphate-buffered saline, cell culture medium, rat serum, and cellular lysate, and results indicated that they are chemically and photophysically stable. Cytotoxicity was studied with ovarian cancer cells having high (SKOV-3), intermediate (OVCAR-3), low (IGROV-1), or null (A2780) expression of FRs. The internalized probe, evaluated in SKOV-3, IGROV-1, and A2780 cells, was in the order Eu(3+)⊂2 > Eu(3+)⊂1 > Eu(3+)⊂3. No internalization was observed for A2780 cells. Such results, together with those obtained in competition experiments of FA versus Eu(3+)⊂2 and FA or Eu(3+)⊂2 versus (3)H-FA, indicate that internalization is receptor-mediated and that Eu(3+)⊂2 shows high selectivity and specificity for FR.

Tuning of the excitation wavelength in Eu3+-aminophenyl based polyfluorinated β-diketonate complexes: a red-emitting Eu3+-complex encapsulated in a silica/polymer hybrid material excited by blue light

A series of new antenna complexes of Eu³⁺ based on aminophenyl β-diketonate ligands was designed and their photophysical properties were evaluated.

The role of the [CpM(CO)2]− chromophore in the optical properties of the [Cp2ThMCp(CO)2]+ complexes, where M = Fe, Ru and Os. A theoretical view

SO-TDDFT calculations shows that transition metals sensitize the emission of Th ion in the present unsupported complexes.

Spectroscopic studies of lanthanide complexes of varying nuclearity based on a compartmentalised ligand

Spectroscopic studies of lanthanide-based coordination compounds of varying nuclearity with a compartmental ligand which show NIR luminescence.

The first example of Tb3-containing metallopolymer-type hybrid materials with efficient and high color-purity green luminescence

In the obtained Tb³⁺-based efficient (Φ_overall = 76–83%) and high color-purity green luminescent 3@PMMA from doping and metallopolymer-type Poly(NBE-3), grafting endows a higher-concentration self-quenching.

A 3-D metal–organic framework with a rutile topology network, right- or left- handed helical chains and tunable UV-to-visible photoluminescence

A solvothermally synthesized 3-D Cd(ii) metal–organic framework with rutile topology was found containing right- or left- handed helices in its structure, and emitting tunable UV-to-visible photoluminescence.

Novel photoluminescent chiral liquid crystalline oligomers containing lanthanide ions

Chiral liquid crystalline oligomers with lanthanide ions distributed in helical matrixes can emit red or green light.

Significant developments in rare-earth-containing polyoxometalate chemistry: synthetic strategies, structural diversities and correlative properties

In this article, the major progress in rare-earth containing polyoxometalates made in the past decade involving synthetic strategies, structural characteristics and some significant properties related to optics, catalysis and magnetism is highlighted and discussed.

Two types of novel tetra-iron substituted sandwich-type arsenotungastates with supporting lanthanide pendants

Two classes of novel tetra-iron substituted sandwich-type arsenotungastates with supporting lanthanide pendants have been synthesized and characterized.

Lanthanide complex-incorporated periodic mesoporous organosilica nanospheres with tunable photoluminescence

Functional DPA (N,N-bis(trimethoxysilylpropyl)-2,6-pyridine dicarboxamide) can be successfully incorporated into mesoporous silica frameworks of regular spherical morphology to accommodate photoluminescent rare-earth metal centres.

Lanthanide coordination frameworks constructed from 1,3-benzenedicarboxylate, oxalate and 1,10-phenanthroline: crystal structure, multicolor luminescence and high-efficiency white light emission

3D frameworks were constructed from tetrameric Ln₄ as SBUs by 1,3-BDC and ox. The Yb:Tb:Eu doped complex reveals significant multicolor luminescence. High-efficiency white light emission was achieved.

Synthesis of lanthanide-based SBA-15 mesoporous hybrids by a novel route

The ligand N

Tailoring functionality through synthetic strategy in heterolanthanide assemblies

Three classes of heterolanthanide assemblies, multi-dimensional frameworks (A), discrete polynuclear molecules (B) and preformed coordinated units connected by a linker (C), are discussed. Potential functionalities arising from the distance-dependent coexistence or interplay of the physical properties are pointed out.

Nano- and micro-sized rare-earth carbonates and their use as precursors and sacrificial templates for the synthesis of new innovative materials

Rare-earth carbonate nano- and micro-materials are reviewed, focusing on factors that influence the morphology and luminescence, as well as their applications as precursors and sacrificial templates for other materials.

Embedding lanthanide-functionalized polymers into hollow mesoporous silica spheres: a ship-in-a-bottle approach to luminescent hybrid materials

Using hollow mesoporous silica spheres (HMSS) as host (“bottle”) and 4-vinylpyridine (4VP), Ln(iii) chlorides (Ln = Eu, Tb), and 1,10-phenanthroline (Phen) as “ship” components gives facile access to luminescent hybrid materials.

Homodinuclear lanthanide {Ln2} (Ln = Gd, Tb, Dy, Eu) complexes prepared from an o-vanillin based ligand: luminescence and single-molecule magnetism behavior

Synthesis, structure, magnetism and photophysical properties of a series of homodinuclear lanthanide complexes are reported.

Achieving visible light excitation in carbazole-based Eu3+–β-diketonate complexes via molecular engineering

A series of visible light excited Eu³⁺–carbazole based β-diketonate complexes has been developed by molecular engineering.

Highly luminescent lanthanide CPs based on dinuclear cluster: crystal structure and sensitive Trp sensor

A lanthanide coordination polymer is explored as Trp sensor. The possible sensing mechanism is the combination between Trp and Tb³⁺, which improves the antenna effect.

A macrocyclic tetraamine bearing four phenol groups: a new class of heptadentate ligands to provide an oxygen-sensitive luminescent Tb(iii) complex with an extendable phenol pendant arm

The potentially N₄O₄-octadentate ligand unprecedentedly coordinates to the Tb³⁺ion in a N₄O₃-heptadentate fashion and provides a highly luminescent and highly oxygen-sensitive terbium(iii) complex.

Layered exfoliable crystalline materials based on Sm-, Eu- and Eu/Gd-2-phenylsuccinate frameworks. Crystal structure, topology and luminescence properties

New layered 2D MOFs based on 2-phenylsuccinate, Sm, Eu and Eu/Gd are a suitable platform for obtaining exfoliatable frameworks with luminescence properties for potential applications as thin films.

Influence of the coordination environment on slow magnetic relaxation and photoluminescence behavior in two mononuclear dysprosium(iii) based single molecule magnets

Two luminescent mononuclear Dy(iii) based complexes with SMM behaviour have been reported. The SMM behaviours differ due to the slight variation of local symmetry around the Dy(iii) centers and photoluminescence study showed quantum yields of 0.98 and 1.44%.

Intriguing multichannel photoinduced electron transfer in lanthanide(iii)–diphenylamine systems

Trivalent lanthanide ions interact with excited diphenylamine through the photoinduced electron transfer mechanism intriguingly engaging their multiple vacant electronic states.

Analysis of the electrostatics in DyIII single-molecule magnets: the case study of Dy(Murex)3

A Dy^III-based single-molecule magnet is reported. Ab initio calculations highlight that molecular symmetry plays a predominant role over site symmetry in determining the shape and orientation of Dy^III magnetic anisotropy.

A flexible zwitterion ligand based lanthanide metal–organic framework for luminescence sensing of metal ions and small molecules

A new 3D luminescence LnMOF was synthesized using a tripodal flexible zwitterion ligand which takes a chair-shaped configuration. The compound displays highly selective luminescence sensing of the Fe³⁺ ion and nitrobenzene.

DFT calculations, spectroscopic, thermal analysis and biological activity of Sm(III) and Tb(III) complexes with 2-aminobenzoic and 2-amino-5-chloro-benzoic acids

The complexes of Sm(III) and Tb(III) with 2-aminobenzoic acid (anthranilic acid, AA) and 2-amino-5-chlorobenzoic acid (5-chloroanthranilic acid, AACl) were synthesized and characterized based on elemental analysis, IR and mass spectroscopy. The data are in accordance with 1:3 [Metal]:[Ligand] ratio. On the basis of the IR analysis, it was found that the metals were coordinated to bidentate anthranilic acid via the ionised oxygen of the carboxylate group and to the nitrogen of amino group. While in 5-chloroanthranilic acid, the metals were coordinated oxidatively to the bidentate carboxylate group without bonding to amino group; accordingly, a chlorine-affected coordination and reactivity-diversity was emphasized. Thermal analyses (TGA) and biological activity of the complexes were also investigated. Density Functional Theory (DFT) calculations at the B3LYP/6-311++G (d,p)_ level of theory have been carried out to investigate the equilibrium geometry of the ligand. The optimized geometry parameters of the complexes were evaluated using SDDALL basis set. Moreover, total energy, energy of HOMO and LUMO and Mullikan atomic charges were calculated. In addition, dipole moment and orientation have been performed and discussed.

Spectroscopic, luminescence and in vitro biological studies of solid ketoprofen of heavier trivalent lanthanides and yttrium(III)

Solid-state compounds of the general formulae [ML3] (M=Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y; L=ketoprofen) were synthesized and characterized using infrared, diffuse reflectance and luminescence spectroscopies. IR data suggested that the carboxylate group in ketoprofen is coordinated to the metals as a bidentate ligand. The triplet state energy level was determined using the Gd(3+) complex, which exhibited a ketoprofen blue luminescence when excited in the UV region. The compound containing Tb(3+) ion was sensitized by the ligand and emitted in the green region of the visible spectrum. On the other hand, for the analogous species containing the dysprosium ion, a competition for luminescence between the Dy(3+) and the ligand levels was observed. Finally, Tm(3+) complex exhibits only ligand luminescence. These optical behaviors are discussed based on rare earth energy diagrams. In addition, the compounds were evaluated for their anti-inflammatory activities. All the compounds showed a higher production of H2O2 and IL-10 than the ketoprofen, suggesting that the compounds exhibited an immunomodulatory effect and this opens up new perspectives for immunotherapeutic approaches.

Supramolecular self-assembly enhanced europium(III) luminescence under visible light

In this paper, we report on the luminescence of europium by directly exciting europium ions with visible light in aqueous medium. Upon replacing all the water molecules that coordinate around a central europium ion with a ditopic ligand 1,11-bis(2,6-dicarboxypyridin-4-yloxy)-3,6,9-trioxaundecane (L2EO4), the quenching from water molecules is efficiently eliminated, offering considerable europium emission. By stoichiometrically mixing with a positively charged block polyelectrolyte, the negatively charged L2EO4-Eu coordinating complex can be transformed into a coordination 'polymer', which simultaneously forms electrostatic micelles with further enhanced europium fluorescence emission, owing to the increased fraction of L2EO4-coordinated Eu(III) as revealed by the fluorescence lifetime measurements. This approach avoids the use of the antenna effect that often utilizes UV light as the irradiation source. We further use those micelles for bio-imaging, and for the first time demonstrate the use of directly excited Eu-containing nano-probes for in vivo fluorescence imaging in small animals under visible excitation. Although literature results have shown that the direct excitation of europium ions in water may lead to emissions in the presence of coordinating ligands, those emissions were too weak to be applied due to the remaining water molecules in the coordination sphere. Our work points out that the direct excitation of europium can generate considerable europium emission given that all the water molecules in the coordination sphere are excluded, which does not only greatly reduce tedious lab work in synthesizing antenna molecules, but also facilitates the application of europium in aqueous medium under visible light.