A multi-color and white-light emissive cucurbituril/ terpyridine/ lanthanide supramolecular nanofiber

The enhanced lanthanide white-emission in solid by cucurbituril-based supramolecular assembly may provide a new strategy for smart light-emitting materials.     

Gd_3Al_5O_(12)∶Eu~(3+)柠檬酸盐硝酸盐燃烧法合成及其发光性能研究

采用柠檬酸盐硝酸盐燃烧法,在较低的温度(900℃)下成功地合成单一晶相Gd3Al5O12∶Eu3+发光粉体,紫外激发荧光光谱分析表明,粉体615 nm和593 nm荧光发射源于Eu3+的5D0-7F2和5D0-7F1跃迁.该方法中各工艺条件(如pH值、柠檬酸/金属离子比、煅烧温度)对Gd3Al5O12∶Eu3+发光性能均有影响,通过试验得出了获得最佳发光性能荧光粉体的工艺参数.     

Luminescence of Eu~(2 ) in Strontium Aluminum Oxide System with Long Decay Property

Luminescentmaterialshavinglongdecayperi0dhaveat-IIactedmuchinterestduetotheirpotentialwidespreadaPplicati0ns.Recently,alongdecayluminescentp0wderhavingthecomPositionofSrAl2O4activatedwithEu' wasreportedandregardedasthebestcandidateforpracticalaPPlicationbecauseofitsuniqueadVantages0veritsprecursors.l'2Inthispaper,wereportthesynthesisofthelongdecayluminescentpowderandtheinnuence0fthemolarratioofAlt0sr0ntheethessioncolor.Toproducethelundnescentp0wder,amixtureofSrCO3,Al2O3,Eu2O3andsomesol…     

Investigation on relation between TL and OSL of Li2B4O7:Cu, In

Polycrystal Li₂B₄O₇ (LBO) doped with Cu and In was prepared and then sintered at different temperatures. X-ray diffraction (XRD) was applied to get the parameters of the LBO structure, thermoluminescence (TL) and optically stimulated luminescence (OSL) were measured, and a second-order exponential decay model was fitted to the OSL decay curves. The results indicate that the original number of OSL traps that have captured electroncs is linearly related with the sum of TL decay during the OSL process. Mean decay constant of OSL is related to the sintered temperature. The possible reason is that the sintered temperature affects the crystal sizes of the polycrystal, and consequently affects the stimulating lights’s intensity and the photoionization cross-section of the electrons, which have been captured by the traps. __________ Translated from Acta Scientiarum Naturalium Universitatis Sunyatseni, 2005, 44(4) (in Chinese)     

Effect of the coordination sphere of d<Superscript>0</Superscript> metallocene on triplet-triplet energy transfer

The triplet nature of rare long-lived states of d⁰ metallocenes formed upon ligand-to-metal energy transfer was confirmed by studies of triplet-triplet charge transfer in biscyclopentadienyl complexes Cp₂MCl₂ (M = Zr (1), Hf (2)). The interaction between precatalysts and substrates of catalytic polymerization systems, viz., complexes 1 and 2 and unsaturated hydrocarbons (alkenes and dienes), was studied in the region of concentrations close to catalytic values. For organometallic π-complexes, it has been shown for the first time that, in the case of the unsaturated hydrocarbons, the efficiency of energy transfer obeys the Perrin equation. The process occurs at distances R ₀ close to the diameter of the interacting molecules and is well described by the exchange-resonant mechanism of interaction. In the case of the cyclopentadiene-Cp₂MCl₂ (M = Zr, Hf) systems, R ₀ = 14.6 Å. A linear relationship between the critical radius of the quenching sphere R ₀ and the number of carbon atoms in a linear α-olefin has been revealed for the first time and evidences the formation of a π-complex between the precatalyst and substrate molecules. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 35–39, January, 2007.     

New silver(i) thiazole-based coordination polymers: structural and photophysical investigation

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Singlet Energy Transfer as the Main Pathway in the Sensitization of Near‐Infrared Nd3+ Luminescence by Dansyl and Lissamine Dyes

In general, sensitization of lanthanide(III ) ions by organic sensitizers is regarded to take place via the triplet state of the sensitizers. Herein, we show that in dansyl‐ and lissamine‐functionalized Nd³⁺ complexes energy transfer occurs from the singlet state of the sensitizers to the Nd³⁺ center. No sensitized emission was observed in the corresponding complexes with Er³⁺, Yb³⁺, and Gd³⁺ ions. Furthermore, the fluorescence of the sensitizers was quenched only in the Nd³⁺ complex and not in the complexes with the other ions. Only Nd³⁺ centers can accept energy from the singlet state of the dyes, because the excited states of Nd³⁺ have a high spectral overlap with the fluorescence of the dansyl and lissamine sensitizers, and because the selection rules allow a fast energy transfer, which apparently is competitive with the fluorescence.     

Synthesis of Eu(III) and Tb(III) Complexes with Two New Amide Type Podands and Their Luminescence Properties

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Crystal Structure and Luminescence of a Europium Coordination Polymer {[Eu(p-MOBA)_3·2H_2O]·0.5H_2O· 0.5(4,4′-bipy)}_∞

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Structure‐Dependent Photoinduced Electron Transfer in Fullerodendrimers with Light‐Harvesting Oligophenylenevinylene Terminals

Oligophenylenevinylene (OPV)‐terminated phenylenevinylene dendrons G1 – G4 with one, two, four, and eight “side‐arms”, respectively, were prepared and attached to C₆₀ by a 1,3‐dipolar cycloaddition of azomethine ylides generated in situ from dendritic aldehydes and N‐methylglycine. The relative electronic absorption of the OPV moiety increases progressively along the fullerodendrimer family C₆₀G1 – C₆₀G4 , reaching a 99:1 ratio for C₆₀G4 (antenna effect). UV/Vis and near‐IR luminescence and transient absorption spectroscopy was used to elucidate photoinduced energy and electron transfer in C₆₀G1 – C₆₀G4 as a function of OPV moiety size and solvent polarity (toluene, dichloromethane, benzonitrile), taking into account the fact that the free‐energy change for electron transfer is the same along the series owing to the invariability of the donor–acceptor couple. Regardless of solvent, all the fullerodendrimers exhibit ultrafast OPV→C₆₀ singlet energy transfer. In CH₂Cl₂, the OPV→C₆₀ electron transfer from the lowest fullerene singlet level (¹C₆₀*) is slightly exergonic (ΔG_CS≈0.07 eV), but is observed, to an increasing extent, only in the largest systems C₆₀G2 – C₆₀G4 with lower activation barriers for electron transfer. This effect has been related to a decrease of the reorganization energy upon enlargement of the molecular architecture. Structural factors are also at the origin of an unprecedented OPV→C₆₀ electron transfer observed for C₆₀G3 and C₆₀G4 in apolar toluene, whereas in benzonitrile, electron transfer occurs in all cases. Monitoring of the lowest fullerene triplet state by sensitized singlet oxygen luminescence and transient absorption spectroscopy shows that this level is populated through intersystem crossing and is not involved in photoinduced electron transfer.