Amine-grafted on lanthanide metal-organic frameworks:Three solid base catalysts for Knoevenagel condensation reaction

A post-synthetic modification strategy has been used to prepare three solid base catalysts, including Er（btc）（ED）075（H2O）0.25 （2, btc = 1,3,5-benzenetricarboxylates, ED = 1,2-ethanediamine）, Er（btc）（PP）0.55（H20）0.45 （3, PP = piperazine）, and Er（btc）（DABCO）0.15（H2O）0.85 （4, DABCO = 1,4- diazabicyclo[2.2.2]octane）, by grafting three different diamines onto the coordinatively unsaturated Er（III） ions into the channels of the desolvated lanthanide metal-organic framework （Er（otc））. The resulting metal-organic frameworks were characterized by elemental analysis, thermogravimetric analysis, powder X-ray diffraction, and N2 adsorption. Based on its higher loading ratio of the diamine, as well as its greater stability and porosity, catalyst 2 exhibited higher catalytic activity and reusability than catalysts 3 and 4- for the Knoevenagel condensation reaction. The catalytic mechanism of 2 has also been investigated using size-selective catalysis tests.

New Opportunities for Lanthanide Luminescence

Trivalent lanthanide ions display fascinating optical properties. The discovery of the corresponding elements and their first industrial uses were intimately linked to their optical properties. This relationship has been kept alive until today when many high-technology applications of lanthanide-containing materials such as energy-saving lighting devices, displays, optical fibers and amplifiers, lasers, responsive luminescent stains for biomedical analyses and in cellulo sensing and imaging, heavily rely on the brilliant and pure-color emission of lanthanide ions. In this review we first outlined the basics of lanthanide luminescence with emphasis on f-f transitions, the sensitization mechanisms, and the assessment of the luminescence efficiency of lanthanide-containing emissive molecular edifices. Emphasis was then put on two fast developing aspects of lanthanide luminescence： materials for telecommunications and light emitting diodes, and biomedical imaging and sensing. Recent advances in NIR-emitting materials for plastic amplifiers and waveguides were described, together with the main solutions brought by researchers to minimize non-radiative deactivation of excited states. The demonstration in 1999 that erbium tris（8-hydroxyquinolinate） displayed a bright green emission suitable for organic light emitting diodes （OLEDs） was followed by realizing that in OLEDs, 25% of the excitation energy leads to singlet states and 75% to triplet states. Since lanthanide ions are good triplet quenchers, they now also play a key role in the development of these lighting devices. Luminescence analyses of biological molecules are among the most sensitive analytical techniques known. The long lifetime of the lanthanide excited states allows time-resolved spectroscopy to be used, suppressing the sample autofluorescence and reaching very low detection limits. Not only visible lanthanide sensors are now ubiquitously provided in medical diagnosis and in cell imaging, but the feasibility of using NIR emission of ions such as YbⅢ is now being tested because of deeper penetration in biological tissues.

Prolonging charge-separation states by doping lanthanide-ions into {001}/{101} facets-coexposed TiO_(2) nanosheets for enhancing photocatalytic H_(2) evolution

Ultrathin TiO_(2)nanosheets with coexposed{001}/{101}facets have attracted considerable attention because of their high photocatalytic activity.However,the charge-separated states in the TiO_(2)nanosheets must be extended to further enhance their photocatalytic activity for H_(2)evolution.Herein,we present a successful attempt to selectively dope lanthanide ions into the{101}facets of ultrathin TiO_(2)nanosheets with coexposed{001}/{101}facets through a facile one-step solvothermal method.The lanthanide doping slightly extended the light-harvesting region and markedly improved the charge-separated states of the TiO_(2)nanosheets as evidenced by UV-vis absorption and steady-state/transient photoluminescence spectra.Upon simulated sunlight irradiation,we observed a 4.2-fold enhancement in the photocatalytic H_(2)evolution activity of optimal Yb^(3+)-doped TiO_(2)nanosheets compared to that of their undoped counterparts.Furthermore,when Pt nanoparticles were used as cocatalysts to reduce the H_(2)overpotential in this system,the photocatalytic activity enhancement factor increased to 8.5.By combining these results with those of control experiments,we confirmed that the extended charge-separated states play the main role in the enhancement of the photocatalytic H_(2)evolution activity of lanthanide-doped TiO_(2)nanosheets with coexposed{001}/{101}facets.

Preparation of Ternary Lanthanide Complexes with Unsaturated Acid and 1,10-Phenanthroline, and Their Anti-Inflammatory Action

Four ternary lanthanide complexes with unsaturated acid and 1,10-phenanthroline are prepared in methanol and characterized by elemental analysis, molar conductance, UV, IR, (()~1H) NMR and XPS. The results from this paper show that the complexes Ln(phen)(SA)_3·2H_2O or Ln(phen)(CA)_3·H_2O (Ln=Ce(Ⅲ), Sm(Ⅲ) and Eu(Ⅲ), (phen=1,10-)phenanthroline, SA=Sorbate and CA=Cinnamate) has better anti-inflammatory effect than cerium nitrate and their gremores are steadier than cerium nitrate gremor. And there is a kind of medicament which can replace the cerium nitrate gremor completely in treating burn.

A New 3-D Lanthanide Porphyrin: Synthesis,Structure and Photophysical Properties

A new lanthanide porphyrin, [Smm（H3TPPSHI）]n-nH20 （1, H6TPPS = tetra（4- sulfonatophenyl）porphyrin）, has been synthesized through a hydrothermal reaction and structurally characterized by single-crystal X-ray diffraction. Compound 1 crystallizes in the P4/mcc space group of tetragonal system： a = 15.3683（12）, c = 9.895（2）/k, V = 2337.0（5） A3, C44H29N4OI3SaSm, Mr = 1100.30, Z = 2, Dc = 1.564 g/cm3, S = 1.063,μ（MoKa） = 1.502 mm-1, F（000） = 1102, R = 0.0583 and wR = 0.1666. Compound 1 is characteristic of a three-dimensional （3-D） framework with a slightly distorted square-antiprism eight-coordinated Sm3＋ ion. Fluorescent study revealed that compound 1 exhibits an emission in the red region. The fluorescence quantum yield and lifetime of 1 were determined to be 3.5% and 9.1 ns, respectively. UV-vis absorption spectra were also investigated.

Crystal Structure and Luminescence Property of Lanthanide Complexes with 2-Fluorobenzoic Acid and 2,2′-Bipyridine

The two compounds of [Ln（2-FBA）3·2,2＇-bpy ]2（2-FBA = 2-fluorobenzoato, 2,2＇-bpy = 2,2＇-bipyridine, Ln = Eu（1 ）, Dy（2）） were synthesized and their structures were determined by X-ray diffraction method. Crystallized complexes 1 and 2 are isomorphous, monoelinie system with P21/n space group. The two complexes are binuclear molecule with an inversion center. The two lanthanide ions are linked by four bridged 2-FBA ligands and each lanthanide ion is further bonded to one chelated bidentate 2-FBA ligand and one 2,2＇-bipyridine molecule. The coordination number of metal ion is eight. The europium complex exhibits strong red fluorescence. ^5D0→^7Fj（j = 1 - 4） transition emission of Eu^3＋ ion was observed.

Lanthanide-regulated oxygen evolution activity of face-sharing Ir〇6 dimers in 6H-perovskite electrocatalysts

The development of efficient oxygen evolution electrocatalysts with reduced noble metal uses is a critical challenge for the deployment of various advanced energy conversion technologies.Here,a series of lanthanide-contained 6H-perovskites with a formula of Ba3LnIr2〇9(Ln=lanthanides)are investigated as oxygen evolution electrocatalysts,whose active subunits(i.e.,face-sharing Ir〇6 dimers)can be regulated by the lanthanides in terms of catalytic activity.By using density functional theory(DFT)calculations,we establish the theoretical trend in activity for Ba3LnIr2〇96H-perovskites,the activity of which is correlated with the difference of adsorption free energy(△G〇-△Goh)between O*and OH*reaction intermediates.We further establish a volcano curve between△Go—△Goh and the calculated 0 p-band center Among the Ba3LnIr2〇96H-perovskites,Ba3Lalr2〇9 locates at the peak of volcano curve,and correspondingly is the most active electrocatalyst due to the optimal 0 p-band property.

Possible Involvement of NADPH Oxidase in Lanthanide Cation-Induced Superoxide Anion Generation in BY-2 Tobacco Cell Suspension Culture

A rapid and concentration-dependent generation of superoxide anion （·O2^-）, measured with a superoxide-specific Cypridina luciferin-derived chemiluminescent reagent, was observed when two lanthanide salts （LaCl3 and CdCl3 ） were added to tobacco （ Nicotiana tabacum） cell suspension culture. Addition of superoxide dismutase （480 U·ml^-1） and Tiron （5 μmol·L^-1） to cell culture suspension decreases the level of lanthanide cation-induced ·O2^- generation, suggesting that ·O2^- generation is extra-cellular. Pretreatment of the cell culture suspension with diphenyleneiodonium （10 and 50 μmol·L^-1 ）, quinacrine （ 1 and 5 mmol· L^-1 ） and imidazol （ 10 mmol· L^-1 ）, inhibitors of NADPH oxidase, notably inhibits the generation of superoxide induced by lanthanide cation, implying the possible involvement of activation of NADPH oxidase. In addition, addition of SHAM （1 and 5 mmol· L^-1）, azide （0.2 and 1 mmol· L^-1 ）, inhibitor of peroxidase, has no influence on ·O2^- generation.

A Series of Lanthanide-organic Frameworks Constructed by Ln_4(OH)_4 Clusters and Mixed Ligands

Three new lanthanide-organic compounds, namely, [Ln_2(OH)_2(oba)(2-pc)_2]n(Ln =Er(1), Ho(2), and Dy(3))(oba = 4,4?-oxybis(benzoate), 2-pc = 2-pyrazinecarboxylic acid) have been obtained under hydrothermal conditions. These compounds are isostructural and exhibit 2 D layered structures by incorporating [Ln_4(μ_3-OH)_4]^(8+) clusters and the mixed linkers of oba and 2-pc. It is interesting that decarboxylation occurred in the ortho position and 2,3-pyrazinedicarboxylic acid was partially transformed into 2-pc under hydrothermal conditions. Compound 3 emits a typical Dy^(3+) emission spectrum. Furthermore, the PXRD, TGA and IR spectra were also studied.

Recent Progress on Spectroscopy of Lanthanide Ions Incorporated in Semiconductor Nanocrystals

Doping luminescent lanthanide ions into semiconductor nanocrystals is an ideal approach for developing nanodevices for various applications. Quantum confinement effects are expected for lanthanide ions doped in small semiconductor nanocrystals. The most recent progress on the synthesis and spectroscopy of lanthanide ions in various semiconductor nanocrystals such as Ⅱ -Ⅵ, Ⅲ-Ⅴ and Ⅳ-Ⅵ families were systematically reviewed, focusing on our recent findings on the optical spectroscopy of Eu^3 ＋ doped in ZnO and TiO2 nanocrystals by wet chemical synthesis. The energy transfer from the band-gap excitation to lanthanides further confirmed that lanthanide ions could be successfully incorporated into the lattice sites in spite of the mismatch in ionic radii.

Synthesis, Characterization and Antioxidative Activity of Lanthanide Complexes with Genistein

Six genistein lanthanide complexes, LnL_2 (OAc)·nH_2O [Ln=La(Ⅲ), Sm(Ⅲ), Eu(Ⅲ), Gd(Ⅲ), (Tb(Ⅲ),) Dy(Ⅲ); L=genistein; n=4, 7, 8] were synthesized and characterized on the basis of elemental analyses, IR, (()~1H) NMR spectra and molar conductivity. The scavenging activity of genistein and five lanthanides complexes on the hydroxyl free radicals (OH·) was also investigated by spectrophotometric methods. The results show that the scavenging activity of the complexes is better than that of the ligand and their scavenging ability can be assembled in the following order: Sm>La>Dy>Eu>Tb>L.

1D Lanthanide Coordination Polymers Based on 3-(Pyridin-4-yl)benzoic Acid: Syntheses, Structures and Luminescent Properties

ABSTRACT Four novel 1D lanthanide coordination polymers with formula [Ln（3,4-pybz）3（HzO）2. H2O]n （Ln = 1 Sm; 2 Eu; 3 Tb; 4 Dy, 3,4-Hpybz = 3-（pyridin-4-yl）benzoic acid） have been synthesized by hydrothermal reactions of lanthanide oxide and 3-（pyridine-4-yl） benzoic acid. Single-crystal X-ray diffraction shows that the four compounds are isostructural. They all crystallize in a monoelinic system, space group P1^-. They have a doubly carboxylate-bridged infinite-chain structure with alternating Ln-（carboxylate）2-Ln linkages and one chelating carboxylate group on each metal center. The Ln ion also combines to two water molecules to form an eight-coordinate square antiprismatic geometry. The pyridine nitrogen atoms of the ligand do not coordinate to the metal centers but direct the formation of a 3D network through hydrogen bonding with coordinated water molecules. The photoluminescent properties of 2 and 3 have been also studied.

Ring-opening Polymerization ofε-Caprolactone Using Lanthanide Tris(4-tert-butylphenolate)s as a Single-component Initiator

The ring-opening polymerization of e-caprolactone (CL) initiated by novel single lanthanide tris(4-tert-butylphenolate)s [Ln(OTBP)3] is reported. Single-component La(OTBP)3 can effectively prepare polycaprolactone (PCL) with over 90% yield and viscosity average molecular weight about 60 x 10 under quite mild conditions: molar ratio of CL to initiator is 1000, 60 C, 2 h in toluene. Mechanism study indicates that the monomer inserts into the growing chain via the break of acyl-oxygen bond of CL.

Hydrothermal Syntheses and Crystal Structures of Three Lanthanide(Ⅲ)Complexes Based on Carboxyl Derivatives of 1,10-Phenanthroline

Three lanthanide（III） complexes [Ln（4-NCP）（1,4-BDC）]n·xn H2O（Ln = Pr（1）, Sm（2）, Nd（3）. 4-HNCP = 2-（4-carboxyphenyl）imidazo（4,5-f）（1,10）phenanthroline, 1,4-H2 BDC = benzene-1,4-dicarboxylic acid） have been hydrothermally synthesized and characterized via elemental analysis, infrared spectrometry and single-crystal X-ray diffraction. Structural analyses revealed that complexes 1~3 possess similar porous three-dimensional frameworks with the point symbol {4^（12）·6~3}. Meanwhile, complexes 1~3 exhibit excellent thermal stabilities and complex 2 exhibits characteristic luminescent property.

Synthesis,structures,thermal and magnetic properties of a series of lanthanide Ln=Sm,Gd,Er,Yb complexes with 4-quinolineacarboxylate

A series of lanthanide binuclear complexes, Ln2（L）6（H2O）4·2H2O（Ln=Sm（Ⅲ）, Gd（Ⅲ）, Er（Ⅲ）, Yb（Ⅲ）, HL=4-quinolinea-carboxylic acid, were synthesized by reactions of corresponding rare earth salts with 4-quinolineacarboxylic acid at room temperature and were characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction.X-ray diffraction analyses showed that they exhibited the same binuclear architecture and crystallized in monoclinic system and P21/c space group.In four complexes, each metal center adopted nine-coordinated mode coordinated by nine O atoms from two H2O molecules and three carboxyls of three ligands, and HL showed three different coordination modes.The variable-temperature magnetic susceptibility showed that complex Gd2（L）6（H2O）4·2H2O performed very weak antiferromagnetic property at low temperature and exchange was almost paramagnetic at high temperature.Complexes Er2（L）6（H2O）4·2H2O and Yb2（L）6（H2O）4·2H2O performed dominating antiferromagnetic coupling.

Two Tri-spin Complexes Based on Lanthanide (Ln~Ⅲ =Dy~Ⅲ and Tb~Ⅲ ) and Nitronyl Nitroxide Radicals: Syntheses, Structures and Properties

Two new tri-spin radical-Ln（III）-radical complexes, [Ln（hfac）3（NITPh-Ph）2] （Ln = Dy （1） and Tb （2）, NITPh-Ph = 4＇-biphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, and hfac = hexafluoroacetylacetonate） have been synthesized and characterized by X-ray diffraction analysis, elemental analysis, IR, Uv-visible and magnetic properties. X-ray analysis reveals that the two complexes are isomorphous and crystallize in the triclinic system, space group P1. For complex 1, a = 12.402（3）, b = 15.414（3）, c = 17.383（3） A, a = 68.61（3）, β = 81.97（3）, y = 79.40（3）°, V = 3031.7（11） A3, Z = 2, Mr = 1401.86, Dc = 1.536 g/cm^3, kt = 1.344 mm^-1, F（000） = 1398, the final GOF = 1.173, R = 0.0670 and wR = 0.1376 for 9035 observed reflections with 1 〉 2a（/）; while for complex 2, a = 12.397（3）, b = 15.391（3）, c = 17.395（4） A, a = 68.62（3）, fl = 81.97（3）, ）, = 79.60（3）°, V = 3030.0（11） A3, Z = 2, Mr = 1398.29, Dc = 1.537 g/cm^3,μ = 1.344 mm-1, F（000） = 1398, the final GOF = 1.130, R = 0.0644 and wR = 0.1382 for 8989 observed reflections with 1 〉 2a（/）. They all consist of the discrete adducts, in which the central Ln（lll） ions are coordinated by six oxygen atoms from three hfacs and two oxygen atoms from nitronyl radicals. The temperature dependency of magnetic susceptibilities for these two complexes is studied, showing that the magnetic interactions are governed by the depopulation of the Ln Stark levels.

Synthesis and Characterization of Some Lanthanide(Ⅲ) Complexes with 4-[N-(2-methoxybenzylimine)formyl]-2, 3-dimethyl-1-phenyl-3-pyazolin-5-one

A series of seven novel lanthanide（Ⅲ ） nitrato complexes with 4-[ N-（2-methoxybenzylimine）formyl] 1-2, 3- dimethyl-1-phenyl-3-pyazolin-5-one （2mbfa）, were synthesized. These complexes were characterized by elemental analysis, molecular mass determination, conductance and magnetic moment measurements, IR, UV-visible, and ^13CNMR spectral studies, In these complexes, the Schiff base, 2mbfa, acts as neutral bidentate ligand by utilizing the carbonyl oxygen and azomethine nitrogen as donor sites. All the three nitrate ions are also coordinated unidentately with 7 coordination for the lanthanide（Ⅲ） ions with a tentative monocapped octahedral geometry for the complexes. All the seven lanthanide（Ⅲ） complexes have a general formula, [ Ln（2mbfa）：（NO3）3 ].

Two Novel 2D Lanthanide-organic Frameworks Based on Different Carboxylate-containing Mixed Ligands

Two novel lanthanide-organic polymers [Er2（pdc）2（o-bdc）（H2O）2]·H2O（1,H2pdc = 2,6-pyridinedicarboxylic acid,o-H2bdc = 1,2-benzenedicarboxylic acid） and Er（Himdc）（mbdc）0.5（H2O）（2,H3imdc = 4,5-imidazoledicarboxylic acid,m-H2bdc = 1,3-benzenedicarboxylic acid） have been synthesized and characterized by elemental analysis,IR,thermogravimetric analysis and X-ray single-crystal diffraction studies.1 crystallizes in monoclinic,space group P21/c,while 2 in the orthorhombic space group Pbcn.Both compounds 1 and 2 display two-dimensional network structures. For 1, the tetranuclear parallelogram {Era} cluster as a building block is further assembled into a wonderful 2D grid, and the layers are interconnected via hydrogen bonds and π-π stacking interactions to yield a 3D supramolecular architecture; for 2, its configuration is a rare double-decker structure. These two complexes represent good examples for using mixcarboxylate-containing ligands to construct diverse 2D lanthanide coordination polymers.

Controlled Synthesis and Optical Properties of Lanthanide-doped Na3ZrF7 Nanocrystals

In this paper,we report for the first time the controlled synthesis of lanthanide ion(Ln3+)-doped tetragonal-phase Na3Zr F7nanocrystals(NCs)via a high-temperature co-precipitation approach.The as-synthesized Na3Zr F7NCs are systematically studied by utilizing the XRD,TEM as well as high-resolution photoluminescence(PL)spectroscopy.The morphology and size for the as-synthesized Na3Zr F7NCs can be finely controlled by changing the experimental parameters such as the amount of precursor,solvent ratio,reaction temperature and time.By utilizing the red-emitting Eu3+ion as an efficient optical/structural probe,the successful hetero-valence doping of Ln3+activators in the lattices of Na3Zr F7NCs is well-established regardless of their different valences and radii between host Zr4+ion and Ln3+dopant.As a result,intense upconversion(UC)luminescence(UCL)ranging from UV to visible and to NIR spectral regions can be readily achieved after the doping of typical UCL couples of Yb3+/Er3+,Yb3+/Tm3+and Yb3+/Ho3+into the lattices of Na3Zr F7NCs when excited by using a 980-nm NIR diode laser.

Synthesis and characterization of lanthanide complexes containing a bulky tridentate [N,N,O] Schiff base ligand

The lanthanide complexes containing a bulky tridentate [N,N,O] Schiff base ligand 3,5-But2-2-（OH）C6H2CH=N-8-C9H6N （HL） were synthesized and characterized. The reaction of anhydrous LnCl3 with NaL formed in situ in a 1：1 molar ratio in THF at room temperature afforded the lanthanide Schiff base dichloride complexes LnLCl2（DME） （Ln=Eu （1）; Sm （2））. Complexes 1 and 2 can be used as precursors for the synthesis of the lanthanide cyclopentadienyl Schiff base derivatives. The reactions of complexes 1 and 2 with one equiv of NaCH3C5H4 in THF provided the desired products LnL（CH3C5H4）CI（THF）.THF （Ln=Eu （3）; Sm （4）） in good isolated yields. These complexes were characterized by elemental analysis, IR spectra, and X-ray structural determination, in the case of complexes 3 and 4. The crystal data of complex 3 are monoclinic, P21/C space group, a=1.3370（2） nm, b=1.5190（2） nm, c=1.8910（3） nm, β=109.846（4）°, V=3.6125（8） nm^3, Z=4, Dc=1.416 mg/m^3,μ=1.847 mm^-1, F（000）=1584, R=0.0707, wR=0.1350. The crystal data of complex 4 are monoclinic, P21/c space group, a=1.3383（1） nm, b=1.5210（2） nm, c=1.8960（2） nm, β =109.878（3）°, V=3.6293（7） nm^3, Z=4, Dc=1.407 mg/m^3, μ=1.728 mm^-1, F（000）= 1580, R=0.0670, wR=0.1385.