New optically active aromatic polyimides II: Synthesis and properties of optically active aromatic polyimide based on (R)-(+)-2,2 '-bis(2-trifluoro-4-aminophenoxy)-1,1 '-binaphthyl

Optically active (R)-(+)-2, 2'-bis(2-trifluoro-4-aminophenoxy)-1, 1'-binaphthyl was prepared from 1, 1'-bi-2-naphthol. The optically active aromatic polyimide was also successfully synthesized. This new polymer has good solubility, thermal stability etc. Its specific rotation was found to be +174 degrees, and its chiroptical property was also studied.

Mechanism-transformation synthesis and characterization of poly(styrene-b-2-ethyl-2-oxazoline) diblock copolymer

By mechanism-transformation (anionic --> cationic) poly(styrene-6-2-ethyl-2-oxazoline) diblock copolymer, PS-b-PEOx, was synthesized in two steps. The first step is the polymerization of styrene block capped with ethylene oxide and its tosylation; the second step is the cationic ring-opening polymerization of 2-ethyl-2-oxazoline. The products were thoroughly characterized by various methods, such as H-1-NMR, IR, DMA, TEM and SAXS. The results show that the copolymer obtained possesses high molecular weight and narrow molecular weight distribution.

Synthesis and properties of optically active poly(amide-imide)s containing axially dissymmetric 1,1 '-binaphthyl moieties

Novel optically active aromatic poly(amide-imide)s (PAIs) containing 1,1'-binaphthyl-2,2'-diyl units in the main chain were prepared by polycondensation reactions of newly synthesized dianhydride, 2,2'-bis(3,4-dicarboxylzenzamido)-1,1'-binaphthyl dianhydride[(S)-BN-DADA and (+/-)-BNDADA], with diamines, The properties of the resulted PAIs were fully characterized by a combination of investigations on inherent viscosity, thermal properties(DSC and TGA), specific rotation, CD and UV-Vis absorbance. These PAIs showed good solubilities, thermal properties and optical stabilities. Interesting UV-Vis absorption behavior of films casted from these PAIs was observed and analyzed.

Sol-gel synthesis and electrical properties of ceria-based solid electrolytes

A series of solid electrolytes (Ce0.8RE0.2)(1-x)MxO2-delta(RE: Rare earth, M: Alkali earth) were prepared by sol-gel methods. XRD indicated that a pure fluorite phase was formed at 800 degrees C. The synthesis temperature by the sol-gel methods was about 700 degrees C lower than by the traditional ceramic method. The electrical conductivity and impedance spectra were measured. XPS showed that the oxygen vacancy increased obviously by doping MO, thus, resulting in the increase of the oxygen ionic transport number and conductivity. The performance of ceria-based solid electrolyte was improved. The effects of RE2O3 and MO on the electrical properties were discussed. The conductivity and the oxygen ionic transport number of (Ce0.8Sm0.2)(1-0.05)Ca0.05O2-delta is 0.126 S.cm(-1) and 0.99 at 800 degrees C, respectively.

Synthesis and properties of aromatic polyimides derived from 2,2,' 3,3 '-biphenyltetracarboxylic dianhydride

2,2,'3,3' -Biphenyltetracarboxylic dianhydride (2,2,'3,3'-BPDA) was prepared by a coupling reaction of dimethyl 3-iodophthalate. The X-ray single-crystal structure determination showed that this dianhydride had a bent and noncopolanar structure, presenting a striking contrast to its isomer, 3,3,'4,4'-BPDA. This dianhydride was reacted with aromatic diamines in a polar aprotic solvent such as N,N-dimethylacetamide (DMAc) to form polyamic acid intermediates, which imidized chemically to polyimides with inherent viscosities of 0.34-0.55 dL/g, depending on the diamine used. The polyimides from 2,2,'3,3'-BPDA exhibited a good solubility and were dissolved in polar aprotic solvents and polychlorocarbons. These polyimides have high glass transition temperatures above 283 degrees C. Thermogravimetric analyses indicated that these polyimides were fairly stable up to 500 degrees C, and the 5% weight loss temperatures were recorded in the range of 534-583 degrees C in nitrogen atmosphere and 537-561 degrees C in air atmosphere. All polyimides were amorphous according to X-ray determination. (C) 1999 John Wiley & Sons, Inc.

Synthesis and characterization of a water-soluble endohedral metallofullerol

A water-soluble endohedral metallofullerol, Pr@C82Om(OH)(n)(m approximate to 10 and n approximate to 10), was successfully synthesized through the reaction of a pure endohedral metallofullerene, Pr@C-82, with a concentrated nitric acid and a subsequent hydrolysis process. The formation of endohedral metallofullerols Pr@C82Om(OH)(n) is thought to involve a NO2 radical formation step, in much the same way as the reaction of empty fullerenes. FT-IR, XPS, and LD-TOF MS techniques were employed to characterize the structure of the endohedral metallofullerol from the above reaction.

Synthesis and characterization of novel crosslinkable side-chain liquid crystalline polyesters

Crosslinkable side-chain liquid crystalline polyesters PCn from N-[n-(4-(4-nitrophenylazo)phenyloxy)alkyl]diethanolamine (Cn, n = 3, 5, 6, 10) as mesogenic monomers and maleic anhydride were synthesized and characterized. The thermal properties of PCn's were studied by means of DSC, polarized optical microscopy (POM) and wide angle X-ray diffraction (WAXD), and the results showed that all the polymers studied exhibit enantiotropic liquid crystallinity. In the molar mass independent region, the relatively high content of cis -CH=CH- groups in the polymer backbone of PC3 causes an increase of the melting temperature (T-m) and a decrease of T-g and isotropisation temperature (T-i). The crosslinking of PCn in the radical polymerization with styrene was confirmed by FTIR spectroscopy. The absorption band at 1300 cm(-1) attributed to the in-plane C-H-bending vibration of trans -CH=CH- in the polymer backbone disappeared after crosslinking, indicating that the trans -CH=CH- functions are consumed in the crosslinking polymerization of styrene.

Synthesis and x-ray structure of a highly symmetrical selenium-centered hexanuclear neodymium complex, [(Cp6Nd6Se13)-Nd-t](-) (Cp-t=eta(5)-(BuC5H4)-C-t)

The half-sandwich tert-buthylcyclopentadienyl neodymium complex [(CpNdCl2)-Nd-t(THF)(2)](2) (1) reacts with Na2Se5 to give organoneodymium polyselenide complex [Na(THF)(6)][(Cp6Nd6)-Nd-t(mu(6)-Se)(mu(2)-Se-2)(6)] (2) which has been characterized by X-ray crystallography.

Synthesis and properties of thermotropic copoly(ester imide)s

A dicarboxylic acid, N,N'-hexane-1,6-diylbis(trimellitimide), was prepared by the reaction of trimellitic anhydride with 1,6-hexane diamine. From the diacid, a series of copoly(ester imide)s had been synthesized by thermal condensation with p-hydroxybenzoic acid and diphenols with different structures. Properties of the resulting copoly(ester imide)s were characterized by polarized light microscopy, differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD). Most of the copoly(ester imide)s formed a nematic phase over a wide temperature range above their melt. The effects of the copoly(ester imide)s composition and the structures of diphenols on the temperature related to liquid crystalline transition were investigated.

Synthesis and characterization of thermotropic liquid crystalline poly(ester imide)s

Two closely series of poly(ester imide)s had been synthesized by solution polycondensation of p-phenylenebis(trimellitate) dianhydride with aliphatic diamines. The differential scanning calorimetry (DSC) traces of the most poly(ester imide)s exhibited two endotherms representing the solid state to anisotropic phase transition (T-m1) and the anisotropic to isotropic melt transition (T-m2), respectively. Observation under polarizing microscope and wide-angle X-ray diffraction (WAXD) measurements suggested that the anisotropic phase formed above the melting paints (T-m1) had a smectic character. The thermogravimetric analyses (TGA) revealed that the thermal stabilities of the poly(ester imide)s were up to 350 degrees C. (C) 1999 John Wiley & Sons, Inc.

A new dinuclear molybdenum(V)-sulfur complex containing citrate ligand: synthesis and characterization of K2.5Na2NH4[Mo2O2S2(cit)(2)].5H(2)O

The complex, K2.5Na2NH4[Mo2O2S2(cit)(2)]. 5H(2)O (1), was obtained by crystallization from a solution of (NH4)(2)MoS4, potassium citrate (K(3)cit) and hydroxyl sodium in methanol and water under an atmosphere of pure nitrogen at ambient temperature. The crystals are triclinic, space group , a = 7.376 (3)Angstrom, b = 14.620 (2) Angstrom, c = 14.661 (1) Angstrom, alpha = 71.10 (1)degrees, beta = 81.77 (1)degrees, gamma = 78.27(2)degrees, R = 0.0584 for 2545 observed (I > 2 sigma (I)) reflections. Single crystal structure analysis reveals that citrate ligand coordinated to molybdenum atom through two carboxylato oxygens and one deprotonated hydroxyl oxygen together with two bridging sulfur atoms and a terminal oxygen atom completes distorted coordination octahedron around each molybdenum atom. Principal dimensions are: Mo = O-t, 1.707 Angstrom (av); Mo-S-b, 2.341 Angstrom (av); Mo-O-(hydroxyl), 2.021 Angstrom (av); Mo-O(alpha-carboxyl), 2.1290 Angstrom (av) and Mo-O(beta-carboxyl), 2.268(av) Angstrom. IR spectrum is in agreement with the structure.

Synthesis and Characterization of Side-Chain Liquid Crystalline (M6MPP/M6NPAP) Copolymers with NLO Properties

A series of novel thermotropic side-chain liquid crystalline polymer based on polymethacrylate backbone containing electron-accepting 4-(4'-nitrophenylazo)phenoxy as nonlinear optical active group and electron-donating 4(4'-methoxyphenyl) phenoxy group as mesogen attached covalently to the backbone through the flexible spacer was prepared and characterized, respectively. The results from differential scanning calorimetry showed that these series of copolymers were enantiotropic liquid crystal with single mesophase. The melting points and the relative enthalpy change of the copolymers depressed with increasing the molar percent of 4'-nitroazobenzene monomer units over 0 similar to 50mol%, but the enthalpies change of the transition from mesophase to isotropic state increased for the copolymers containing 0 similar to 50mol% 4'-nitroambenzene units. The texture observed under polarized optical microscope identified that the copolymers containing 24molar% or more than 24mol% 4-nitroambenzene monomer units could form smectic mesophase with the focal-conic texture. The results detected by WAXD were in good agreement with the results observed by POM.

A ferric molybdenum phosphate with a tunnel: hydrothermal synthesis and structure of (NH3CH2CH2NH3)(2)center dot(NH3CH2CH2NH2)(3)center dot Na center dot[Fe2Mo12O30(PO4)(HPO4)(4)(H2PO4)(3)]center dot 7H(2)O

A new ferric molybdenum phosphate containing a tunnel structure and crystallographically different clusters has been hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction. A probe reaction of the oxidation of acetaldehyde with H2O2 using the tide compound as catalyst was carried out in a liquid-solid system, showing that the title compound had high catalytic activity in the reaction. (C) 1998 Elsevier Science S.A. All rights reserved.

Synthesis and structure of alpha-B-Keggin type heteropoly complex K5H[Co-4(VW9O33)(2)]center dot 5H(2)O

A new complex K5H[Co-4(VW9O33)(2)]. 5H(2)O was prepared and its structure was determined by X - ray diffraction analysis. The anion has alpha - beta - Keggin structure. Two (VW9O33)(7-) moieties (alpha - B isomers) are linked via four Co(11)O-6 groups. The single crystal of the title complex is monoclinic P2(1/n) with a = 1.2307(3) nm, b = 2.1250(4) nm, c = 1.5817(3) nm, beta = 91.86(3)degrees, V = 4.1343 (14) nm(3), R = 0.0895, R-w = 0.2180.

Synthesis and crystal structure of a polymeric erbium(III)-sodium(I) coordination complex of picolinic acid N-oxide

A new Er(III)-Na(I) coordination polymer of stoichiometry [NaEr2L5(H2O)(6)(NO3)](NO3). 3.5H(2)O (HL = picolinic acid N-oxide) has been synthesized and characterized by single-crystal X-ray analysis. Crystals are triclinic, P (1) over bar with a = 9.823(2), b = 12.453(2), c = 20.643(4) Angstrom; alpha = 98.49(3), beta = 101.40(3), gamma = 108.69(3)degrees; V = 2284(1) Angstrom(3); Z = 2. Of the two independent eight-coordinate erbium(III) ions in this complex, one is surrounded by four bidentate chelating L ligands, and the other by one bidentate chelating L ligand, four aqua ligands and two anti-carboxylate oxygen atoms from two neighboring [ErL4] units. The sodium(I) ion is in a distorted octahedral environment, being coordinated by a unidentate nitrate anion, three aqua ligands and two anti-carboxylate oxygen atoms from two adjacent [ErL4] units. The complex is built from zigzag chains of syn-anti carboxylate-bridged erbium(III) moieties directed in the a direction, which are cross-linked pairwise by aqua-bridged dimeric sodium(I) units. The resulting composite polymeric chains are further connected by hydrogen bonds to form a three-dimensional network.