Efficient One-Pot Synthesis of Highly Substituted Thiophene Library from 1,3-Dicarbonyl Compounds

A faccile and efficient one-pot synthesis of highly substituted thiophenes has been developed and employed for the preparation of a small focused library. Treatment of 1,3-dicarbonyl compounds 1 with CS2 in the presence of K2CO3 in DMF at room temperature, followed by stepwise addition of alkyl bromides 2 and methylene active bromides 3, provided via intramolecular cyclization 2,3,4,5-tetrasubstituted thiophenes 4 in yields of 77-94%. This protocol, combining construction and modification of the thiophene ring, increases the structural diversity of final products from readily available materials. A mechanism for the one-pot synthesis of thiophenes of type 4 has been proposed. A small focused library of thiophenes is prepared using the sequential addition of reagents to achieve unique substitution in the 2 and 5 position of the thiophene ring

Syntheses, structures and reactions of a series of beta-diketiminatoyttrium compounds

This paper describes the synthesis and selected reactions of a series of crystalline mono(beta-diiminato) yttrium chlorides 3a, 3b, 4a, 4b, 5a, 5b, 5c and 9. The X-ray structure of each has been determined, as well as of [YCl(L-4)(2)] (6), [Y(L-1)(2)OBut] (7) and [Y{CH(SiMe3)(2)}(thf)(mu-Cl)(2)Li(OEt2)(2)(mu-Cl)](2) (8).

Utilizing a CdTe quantum dots-enzyme hybrid system for the determination of both phenolic compounds and hydrogen peroxide

In this paper, we attempt to construct a simple and sensitive detection method for both phenolic compounds and hydrogen peroxide, with the successful combination of the unique property of quantum dots and the specificity of enzymatic reactions. In the presence Of H2O2 and horseradish peroxidase, phenolic compounds can quench quantum dots' photoluminescence efficiently, and the extent of quenching is severalfold to more than 100-fold increase. Quinone intermediates produced from the enzymatic catalyzed oxidation of phenolic compounds were believed to play the main role in the photoluminescence quenching.

Separation of ternary systems of hydrophilic ionic liquid with miscible organic compounds by RPLC with refractive index detection

A rapid and simple analytical method was developed for the simultaneous and quantitative determination and separation of hydrophilic imidazolium ionic liquids (ILs) (1-butyl-3-methylimidazolium chloride, [C(4)mim]Cl; 1-hexyl-3-methylimidazolium chloride, [C(6)mim]Cl; 1-octyl-3-methylimidazolium chloride, [C(8)mim]Cl; 1-allyl-3-methylimidazolium chloride, [Amim]Cl; or 1-allyl-3-methylimidazolium bromide, [Amim]Br) with miscible ethyl acetate and EtOH and their mixtures using reverse phase liquid chromatography coupled with refractive index detection (RPLC-RI). The influence of 60 to 100% (volume percentage) methanol in the mobile phase on the IL systems ([C(4)mim]Cl, [C(6)mim]Cl, [C(8)mim]Cl, [Amim]Br, or [Amim]Cl)-ethyl acetate-EtOH was investigated.

Failure of the plasma-sprayed coating of lanthanum hexaluminate

Lanthanum magnesium hexaluminate (LaMgAl11O19, LMA) is an attractive material for thermal barrier coatings (TBCs), and the failure of its coating was studied in this work by thermal cycling, X-ray diffraction, dilatometric measurement and thermal gravimetric-differential thermal analysis. The dilatometric measurement indicates that even though the bulk material of LMA has a higher sintering-resistance than the typical TBC material, i.e. yttria-stabilized zirconia (YSZ), the plasma sprayed coating of LMA has two serious contractions due to the re-crystallization of LMA and phase transitions of alumina.

Well-defined higher-molecular-weight polyacrylonitrile via RAFT technique in the presence of disulfide compounds as a source of chain transfer agent

Well-defined polyacrylonitrile with a higher number-average molecular weight (R.) up to 200,000 and a lower polydispersity index (PDI, 1.7-2.0) was firstly obtained via reversible addition-fragmentation chain transfer (RAFT) process. This was achieved by selecting a stable, easy way to prepare disulfide compound intermediates including bis(thiobenzoyl) disulfide (BTBDS) and bis(thiophenylacetoyl) disulfide (BTPADS) to react with azobis(isobutyronitrile) to directly synthesize RAFT agents in situ.

Assembly of supramolecular compounds with water-soluble calix[4]arenes

Three new copper compounds, Cu-2[C12H8N2](2)[C28H2OS4O16][H2O](11.9) (1), Cu-2[C12H8N2](3)[C28H20S4O16][H2O](5) (2), and Cu-2[C12H8N2](4)[C24H12S8O16][H2O](10.5) (3), were hydrothermally synthesized and structurally determined by X-ray diffraction and TG-DTA analyses. Interestingly, Compounds 1 and 2 were synthesized in a one-pot reaction. Complexes 1 and 3 contain capsule units, which are further assembled into three-dimensional (3-D) architectures with a-Po-related topology by pi-pi stacking and/or hydrogen-bonding interactions.

Effects of deposition conditions on composition and thermal cycling life of lanthanum zirconate coatings

Lanthanum, zirconate (La2Zr2O7, LZ) coatings were prepared under four different deposition conditions by electron beam-physical vapor deposition (EB-PVD). The composition, crystal structure, surface and cross-sectional morphology, cyclic oxidation behavior of these coatings were studied. Elemental analysis indicates that the coating composition has partially deviated from the stoichiometry of pyrochlore, and the existence of excess La2O3 is also observed. The deviation could be reduced by properly controlling the electron beam current or by changing the ingot composition.

Synthesis and high-pressure sintering of lanthanum magnesium hexaaluminate

Lanthanum magnesium hexaaluminate is a very important ceramic material for high temperature applications. In this paper lanthanum magnesium hexaaluminate has been synthesized directly by solid-state reaction. The forming mechanism was investigated by XRD. The SEM photographs show that the prepared powders are made of hexagonal plates. These powders can be well sintered at the high temperature (1600 degrees C) under the high pressure (4.5 GPa), and the relative density reaches 94.8%.

Laser glazing of lanthanum magnesium hexaaluminate

Lanthanum magnesium hexaalumminate (LMA) is an important candidate for thermal barrier coatings due to its thermal stability and low thermal conductivity. On the other hand, laser glazing method can potentially make thermal barrier coatings impermeable, resistant to corrosion on the surface and porous at bulk. LMA powder was synthesized at 1600 degrees C by solid-state reaction, pressed into tablet and laser glazed with a 5-kW continuous wave CO2 laser.

Structures and physical properties of n=3 Ruddlesden-Popper compounds Ca4Mn3-xNbxO10 (0 <= x <= 0.2)

The Ruddlesden-Popper series of compounds Ca4Mn3-xNbxO10(x = 0-0.2) have been prepared by solid-state methods. Structural, magnetic, electrical, and magnetoresistive studies were performed on the compounds. Nb doping caused increases in both unit cell volume and octahedral distortion. The magnetization measurements indicated that the doped samples displayed ferromagnetism-like behavior, which could be explained by the double-exchange interaction between Mn4+ and Mn3+ induced by the charge-compensation effect.

Promoting carbonization of polypropylene during combustion through synergistic catalysis of a trace of halogenated compounds and Ni2O3 for improving flame retardancy

The effect of combination between a trace of halogenated compounds (such as ferric chloride and ammonium bromide) and Ni2O3 particles on the carbonization of polypropylene (PP) was investigated during combustion. The results showed a synergistic catalysis of combined halogenated compounds with Ni2O3 in promoting the formation of the residual char during combustion. The investigation on the promotion mechanism showed that halide radical releasing from halogen-containing additives worked as a catalyst to accelerate dehydrogenation-aromatization of degradation products of PR which promote the degradation products to form the residual char catalyzed by nickel catalyst.

Thermal-shock resistance of LnMgAl(11)O(19) (Ln = La, Nd, Sm, Gd) with magnetoplumbite structure

Lanthanide hexaaluminates including LaMgAl11O19, NdMgAl11O19, SmMgAl11O19 and GdMgAl11O19 were synthesized via Sol-Gel method. Due to the anisotropic crystal growth, these oxides crystallize in the form of platelets and the platelet thickness increases with the decrease of rare-earth ionic radius. It was observed that the thermal-shock resistances of LaMgAl11O19, NdMgAl11O19 and SmMgAl11O19 oxides were superior to 8YSZ as proved by water quenching tests. In addition, the thinner the platelet. the more interstices are retained in the sintered specimen, and the better thermal-shock resistance the oxide has. Based on SEM images, it can be seen that the SmMgAl11O19 sample exhibits a mixture of the intergranular and transgranular fracture after thermal cycling failure.

Two Mn(2)(II)Ln(4)(III) (Ln = Gd, Eu) hexanuclear compounds of p-tert-butylsulfinylcalix[4]arene

Two 3d-4f heterometallic compounds of p-tert-butylsulfinylcalix[4] arene were synthesized by the solvothermal method and characterized by some hinged double-dumbbell-like subunits in which two perpendicular dumbbell entities were constructed by an in-between isosceles triangle Mn(II)Ln(2)(III), and two tail-to-tail calixarene molecules, and hinged by the lanthanide-sulfinyl group bonding. The magnetic properties of the title compounds were examined.

Five supramolecular compounds of water-soluble sulfonylcalix[4]arenetetrasulfonate showing two calixarene conformations

Five new compounds of sulfonylcalix[4]arenetetrasulfonate (SC4AS), [H7Na(H2O)(3)(SC4AS)(phen)(5)](H2O)(11.9) (1), [H6Mn(H2O)(4)(SC4AS)(phen)(5)] (H2O)(12.7) (2), [Cu-4(SC4AS) (phen)(6)] (H2O)(4.5) (3), {[Cu (2)(SC4AS) (bpy)(2)][Cu(bpy)(2)(H2O)](2)} (H2O)(6.6) (4), and {[Zn-2(SC4AS) (phen)(2)][Zn(phen)(2)(H2O)(2)](2)} (H2O)(7) (5) (where phen 1,10-phenanthroline and bpy = 2,2'-bipyridine), were synthesized by a hydrothermal method and structurally determined by single crystal X-ray diffraction. The SC4AS ligand adopts partial cone conformation in compounds 1 and 2 and 1,2-alternate form in compounds 3-5. According to the structural analysis and density functional theory (DFT) calculations, we suggest that the metal can affect the conformation of SC4AS.