Ternary lanthanide (Er3+, Nd3+, Yb3+, Sm3+, Pr3+) complex-functionalized mesoporous SBA-15 materials that emit in the near-infrared range

The tertiary lanthanide complexes [Ln(hfth)(3)phen] (Ln=Er, Nd, Yb, Sm) and [Pr(tfnb)(3)phen] have been Successfully covalently attached in the ordered SBA-15 mesoporous materials via a functionalized 1,10-phenanthroline group 5-(N,N-bis-3-(triethoxysilyl)propyl)ureyl-1,10-phenanthroline (Phen-Si). The derivative materials [denoted as Ln(hfth)(3)phen-S15 and Pr(tfnb)(3)phen-S15; Ln=Er, Yb, Nd, Sm; hfth=4,4,5,5,6,6,6-heptafluoro-1-(2-thienyl)hexane-1,3-dionate; tfnb=4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedionate] were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and N-2 adsorption/desorption.

Syndiotactically enriched 1,2-selective polymerization of 1,3-butadiene initiated by iron catalysts based on a new class of donors

A series of phosphoryl (P=O) contained compounds: triethylphosphate (a), diethyl phenyl phosphate (b), ethyldiphenylphosphate (c) triarylphosphates (d and h-m), triphenylphosphine oxide (e), phenyl diphenylphosphinate (f) and diphenyl phenylphosphonate (g) have been prepared. Iron catalysts, which are generated in situ by mixing the compounds with Fe(2-EHA)(3) and (AlBu3)-Bu-i in hexane, are tested for butadiene polymerization at 50 degrees C. Phosphates donated catalysts have been, unprecedently, found to conduct extremely high syndiotactically (pentad, rrrr=46.1-94.5%) enriched 1,2-selective (1,2-structure content=56.2-94.3%) polymerization of butadiene.

Living polymerization of 1,3-butadiene by a Ziegler-Natta type catalyst composed of iron(III) 2-ethylhexanoate, triisobutylaluminum and diethyl phosphite

Living characteristics of facilely prepared Ziegler-Natta type catalyst system consisting of iron(III) 2-ethylhexanoate, triisobutylaluminum and diethyl phosphite have been found in the polymerization of 1,3-butadiene in hexane at 40 degrees C. The characteristics have been well demonstrated by: a first-order kinetics with respect to monomer conversion, a narrow molecular weight distribution (M-w/M-n = 1.48-1.52) of polybutadiene in the entire range of polymerization conversion and a good linearity between M-n and the yield of polymer. Feasible post-polymerization of 1,3-butadiene and block co-polymerization of 1,3-butadiene and isoprene further support the living natures of the catalyst bestowed with.

Selective hydrogenation of nitrobenzene to aniline in dense phase carbon dioxide over Ni/gamma-Al2O3: Significance of molecular interactions

The selective hydrogenation of nitrobenzene (NB) over Ni/gamma-Al2O3 Catalysts Was investigated using different media of dense phase CO2, ethanol, and n-hexane. In dense phase CO2, the total rate of NB hydrogenation was larger than that in organic solvents under similar reaction conditions; the selectivity to the desired product, aniline, was almost 100% over the whole conversion range of 0-100%. The phase behavior of the reactant mixture in/under dense phase CO2 was examined at reaction conditions. In situ high-pressure Fourier transform infrared measurements were made to study the molecular interactions Of CO2 with the following reactant and reaction intermediates: NB, nitrosobenzene (NSB), and N-phenylhydroxylamine (PHA). Dense phase CO2 strongly interacts with NB, NSB, and PHA, modifying the reactivity of each species and contributing to positive effects on the reaction rate and the selectivity to aniline. A possible reaction pathway for the hydrogenation of NB in/under dense phase CO2 over Ni/gamma-Al2O3 is also proposed.

Carbon dioxide pressure induced heterogeneous and homogeneous Heck and Sonogashira coupling reactions using fluorinated palladium complex catalysts

The Heck reaction of iodobenzene and methyl acrylate was investigated with CO2-philic Pd complex catalysts having fluorous ponytails and the organic base triethylamine (Et3N) in the presence of CO2 under solventless conditions at 80 degrees C. The catalysts are not soluble in the organic phase in the absence Of CO2 and the reaction occurs in a solid-liquid biphasic system. When the organic liquid mixture is pressurized by CO2, CO2 is dissolved into the organic phase and this promotes the dissolution of the I'd complex catalysts. As a result, the Heck reaction occurs homogeneously in the organic phase, which enhances the rate of reaction. This positive effect Of CO2 pressurization competes with the negative effect that the reacting species are diluted by an increasing amount of CO2 molecules dissolved. Thus, the maximum conversion appears at a CO2 pressure of around 4 MPa under the present reaction conditions. The catalysts are separated in the solid granules by depressurization and are recyclable without loss of activity after washing with n-hexane and/or water.

Effects of polymerization conditions on hydrophilic groups in aromatic polyamide thin films

For polyamide used in reverse osmosis (RO) membranes, the content of pendant acid groups is critical to its performance. In this work, FTIR was used to analyze the acid contents in the polyamide films prepared via interfacial polymerization of trimesic acid trichloride (TMC) in hexane and 1,3-phenylenediamine (MPDA) in water, and the effects of reaction conditions, including monomer concentrations, time, and temperature, were studied. It was found that more pendant acid groups are present in the polyramide film at higher TMC concentrations or lower MPDA concentrations, and longer reaction times and lower temperatures also favor the formation of the free acids. These results can be explained by the monomer diffusion in the interfacial polymerization process. This work may help the design and fabrication of RO membranes with different hydrophilicity and target performance.

Synthesis and characterization of high-quality ZnS, ZnS : Mn2+, and ZnS : Mn2+/ZnS (core/shell) luminescent nanocrystals

High-quality ZnS, ZnS:Mn2+, and ZnS:Mn2+/ZnS (core/shell) nanocrystals (NCs) were synthesized via a high-boiling solvent process and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectra. The monodisperse ZnS NCs (size = 8 nm), which self-assembled into several micrometer-sized domains, were achieved by adopting poly(ethylene glycol) (PEG) in the reaction process (without using a size-selection process). The obtained ZnS:Mn2+ and ZnS:Mn2+/ZnS core/shell NCs are highly crystalline and quasimonodisperse with an average particle size of 6.1 and 8.4 nm, respectively. All of the as-formed NCs can be well dispersed in hexane to form stable and clear colloidal solutions, which show strong visible emission (blue for ZnS and red-orange for ZnS:Mn2+ and ZnS:Mn2+/ZnS) under UV excitation. The growth of a ZnS shell on ZnS:Mn2+ NCs, that is, the formation of ZnS:Mn2+/ZnS core/shell NCs, resulted in a 30% enhancement in the PL intensity with respect to that of bare ZnS:Mn2+ NCs due to the elimination of the surface defects.

Soluble neodymium chloride 2-ethylhexanol complex as a highly active catalyst for controlled isoprene polymerization

Soluble NdCl3 center dot 3EHOH (2-ethyl hexanol) in hexane combined with AlEt3 is highly active for isoprene polymerization in hexane. The NdCl3 center dot 3EHOH/AlEt3 has higher activity than the typical binary catalyst NdCl3 center dot 3(i)PrOH (isopropanol)/AlEt3 and ternary catalyst NdV3 (neodymium versatate)/AlEt2Cl/Al(i-Bu)(2)H. The molecular weight of polyisoprenes can be controlled by variation of [Nd], [Al]/[Nd] ratio and polymerization temperature and time. The NdCl3 center dot 3EHOH/AlEt3 catalyst polymerized isoprene to afford products featuring high cis-1,4 stereospecificity (ca. 96%), high molecular weight (ca. 10(5)) and relatively narr ow molecular weight distributions (M-w/M-n = 2.0-2.8) simultaneously. More importantly, some living polymerization characteristics were demonstrated: (a) absence of chain termination; (b) linear correlation between M-n and polymer yield; (c) increment of molecular weight in the 'seeding' polymerization. Though some deviation from the typical living polymerization such as molecular weight distribution is not narrow enough and the line of M-n and polymer yield does not extrapolate to zero, controlled polymerization with the current catalyst can still be concluded.

Near-infrared luminescent mesoporous materials covalently bonded with ternary lanthanide [Er(III), Nd(III), Yb(III), Sm(III), Pr(III)] complexes

New near-infrared-luminescent mesoporous materials were prepared by linking ternary lanthanide (Er3+, Nd3+, Yb3+, Sm3+, Pr3+) complexes to the ordered mesoporous MCM-41 through a functionalized 1,10-phenanthroline (phen) group 5-(N,N-bis-3-(triethoxysilyl)propyl)ureyl-1,10-phenanthroline. The resulting materials (denoted as Ln(hfth)(3)phen-M41 and Pr(tfnb)(3)phen-M41; Ln=Er, Yb, Nd, Sm; hfth = 4,4,5,5,6,6,6-heptafluoro-1-(2-thienyl)hexane-1,3-dionate; tfnb = 4,4,4-trifluoro-1-(2-naphthyl)- 1, 3-butanedionate) were characterized by powder X-ray diffraction, N-2 adsorption/desorption, and elemental analysis. Luminescence spectra of these lanthanide-complex functionalized materials were recorded, and the luminescence decay times were measured. Upon excitation at the absorption of the organic ligands, all these materials show the characteristic NIR luminescence of the corresponding lanthanide (Er3+, Nd3+, Yb3+, Sm3+, Pr3+) ions by sensitization from the organic ligands moiety. The good luminescent performances enable these NIR-luminescent mesoporous materials to have possible applications in optical amplification (operating at 1300 or 1500 nm), laser systems, or medical diagnostics.

Efficient organic electroluminescent devices based on an organosamarium complex

Several organic electroluminescent devices with different device structures were fabricated based on an organosamarium complex Sm(HFNH)(3)phen[HFNH=4, 4, 5, 5, 6, 6, 6-heptafluoro-l-(2-naphthvl)hexane-1, 3-dione; phen=1, 10-phenanthroline] as emitter. Their electroluminescent properties were investigated in detail. Although the devices with the optimal structure ITO/TPD (50nm)/ Sm(HFNH)(3)phen (xwt%):CBP (50nm)/BCP (20nm)/AIQ (30nm)/LiF (1 nm),/Al (200nm) show high brightness (more than 400cd/m(2)) and high current efficiency (about 1 cd/A), there are emissions from CBP, BCP and even from AIQ existing in the electroluminescence (EL) spectra besides emission from Sm(HFNH)(3)Phen. The reason to this was discussed. The device with the structure ITO/TPD (50 nm)/ Sm(HFNH)(3)phen (50 nm)/AIQ (30 nm)/LiF (1 nm)/Al (200 nm) exhibits the maximum brightness of 118 cd/m(2) and current efficiency of 0.029 cd/A, and shows emissions from AIQ and Sm(HFNH)(3)phen at high voltages. However, with the BCP hole-block layer added, the device [ITO/TPD (50 nm)/Sm(HFNH)(3)phen (50 nm)/BCP (20 nm)/AIQ (30 nm)/LiF (1 nm)/Al (200 nm)] exhibits pure Sm3+ emission in 2 the EL spectra even at high voltages, with the maximum current efficiency of 0.29cd/A and brightness of 82cd/m(2)

Preparation of silica/polyacrylamide/polyethylene nanocomposite via in situ polymerization

SiO2/polyacrylamide (PAM) composite was prepared via the polymerization of acrylamide in the presence of silica sol in water/hexane emulsion, and pure SiO2 was also prepared without the use of acrylamide in the same way. Field emission scanning electron micrographs (FESEM) showed that PAM covered the silica nanoparticles to form SiO2/PAM nanospheres, which loosely agglomerated to form SiO2/PAM secondary particles, while SiO2 secondary particles were made up of tightly agglomerated silica nanoparticles. Metallocene catalyst was then immobilized over SiO2 and SiO2/PAM respectively to prepare supported metallocene catalyst for ethylene polymerization. Transmission electron micrographs (TEM) showed that support particles broke up to smaller particles and even nanoparticles in polyethylene (PE) matrix when the support particles were the fragile SiO2/PAM secondary particles, which shows a novel way to prepare silica/polyacrylamide/polyethylene nanocomposite.

Triboluminescence of a new europate complex

A new europium (III) complex Eu(HFNH)(3)Phen (HFNH: 4, 4, 5, 5, 6, 6, 6-heptafluoro-1-(2-naphthyl) hexane-1,3-dione; phen: 1, 10-phenanthroline) was synthesized and its triboltuninescent phenomenon was observed. Photoluminescence and triboluminescence spectra were successfully determined. The most intense triboluminescent emission originates front the transition of the, central Eu3+ ion from D-5(0) level to F-7(2) level. The triboluminescent spectrum is basically similar to that of photoluminescence, which correlates with the disorders of F atoms.

Studies on the stability of polyazamacrocycle-Eu (Tb) by potentiometry and its catalytic hydrolysis on phosphate diester

The stability constants and species distributions of complexes of two lanthanide ions, Eu (III) and Tb(III), with a macrocyclic ligand, 3,6, 9, 17 20, 23-hexaazo-29, 30-dihydroxy-13, 27-dimethyl-tricylco-[23,3,1,1(11,15)] triaconta-1 (28) 11,13,15 (30), 25 26-hexane (BDBPH), in 1: 1 and 2: 1 system, were determined potentiometrically in 50% ethanol solution, at 35.0 degrees C and I = 0.100 mol/L (KCl). The two metal ions could form deprotonated mono- or dinuclear complexes with BDBPH with high stability after the three protons of the ligand completely neutralized. At higher pH values, Eu(M) could not form hydroxo complexes with BDBPH, while Tb(III) could form hydroxo complexes in the types of M2L(OH) M2L(OH)(2) and M2L (OH)(2). The kinetic study on the hydrolysis reaction of his (4-nitrophenyl) phosphate (BNPP) catalyzed by Tb-BDBPH system (2:1) was carried out in aqueous solution (pH 7.0 similar to 10.0) at 35 degrees C with I = 0.1000 mol/L (KCl). The second-order rate constant k(BNPP) (2.3 x 10(-3) (mol/L)(-1)center dot s(-1)) was determined. The dinuclear monohydroxo species, L-Tb-2-OH, is kinetically active species.

Crystal structure of tris(methylcyclopentadienyl) tetrahydrofuranatosamarium

The first crystal structure of tris(methylcyclopentadienyl) tetrahydrofuranato (THF) lanthanide complexes, (CH3Cp)(3)Sm . THF, is determined. The complex crystallizes from mixed solvents of tetrahydrofuran and hexane as a monomer in the orthorhombic space group Pc2(1)n with the unit cell parameters a = 9.135(2) Angstrom, b = 13.263(2) Angstrom, c = 16.176(3) Angstrom, and Z = 4.

Electroluminescence based on a beta-diketonate ternary samarium complex

The triplet energy state of the HTH [HTH: 4,4,5,5,6,6,6-heptafluoro-1-(2-thienyl) hexane-1,3-dione] ligand was measured to be 20 400 cm(-1), which indicated that Sm(HTH)(3) phen (phen: 1,10-phenanthroline) is a good complex to produce strong PL intensity and high fluorescence yield. Electroluminescent (EL) devices using the Sm( HTH) 3 phen complex as the emissive center were fabricated by vapor deposition and spin-coating methods. The relative intensity of the EL spectra changed compared to the photoluminescence (PL) spectrum, which suggested that the luminescence mechanisms of PL and EL have differences. A luminance of 9 cd m(-2) and a higher brightness of 21 cd m(-2) were obtained from the devices ITO/TPD (40 nm)/ Sm( HTH)(3) phen (50 nm)/ PBD (30 nm)/ Al (200 nm) and ITO/PVK (40 nm)/ PVK : Sm( HTH)(3) phen (2.5 wt%, 50 nm)/ PBD (30 nm)/ Al (200 nm), respectively.