Interpolymer complex between poly(ethylene oxide) and poly(carboxylic acid)

An interpolymer complex was prepared by mixing aqueous solutions of poly(ethylene oxide) (PEO) and of a poly(carboxylic acid), i.e., poly(acrylic acid)(PAA), poly(methacrylic acid)(PMAA), or styrene-maleic acid copolymer(PSMA). The complexation mechanism was discussed on the basis of results of such experimental methods as viscosity, potentiometric titration, and turbidimetry. The hydrogen bond is primarily involved in these complexations, but the influence of hydrophobic interaction on complexation can not be ignored. If the degree of dissociation α of carboxylic acid or the degree of polymerization P_n of PEO was perceptibly changed, a stable complex was obtained at about α 0.1 or P_n (PEO) = 40 for PMAA, 200 for PAA. This fact indicates that more than a definite number of binding sites are necessary for a stable interpolymer complex to be formed and that cooperative interaction among active sites plays an important role in complex formation.     

Anionic NaCl-type frameworks of [Mn(II)(HCOO)(3)(-)], templated by alkylammonium, exhibit weak ferromagnetism

We present the synthesis, characterization by IR, TGA, single crystal X-ray structure and magnetic properties of a novel series of NaCl-type frameworks of [AmineH(+)][Mn(HCOO)(3)(-)], templated by alkylammonium. The anionic NaCl-framework of [Mn(HCOO)(3)(-)] is counter-balanced by the alkylammonium cations located in the cavities of the framework to which they are hydrogen-bonded. The divalent manganese ions have octahedral geometry and are bridged by the formate in an anti-anti mode of coordination. All the compounds exhibit long-range antiferromagnetism below 9 K with a slight non-collinear arrangement of the moments. The canting, likely due to second-order spin-orbit coupling, is via a Dzyaloshinski-Moriya antisymmetric exchange mechanism. A spin-flop is observed in each case at fairly low fields. An orthorhombic to monoclinic transformation was observed for the protonated cyclotrimethyleneamine that is accompanied by localization of the cations into two positions below 240 K from the rapid dynamic flipping of the ring observed at room temperature.     

Spectrophotometric determination of nitrogen in vanadium,titanium and uranium with thymol after alkali fusion

Vanadium metal packed into a nickel boat with potassium hydroxide, is fused at 500–600°C, and the volatilized ammonia is absorbed in dilute hydrochloric acid. The ammonia is converted to monochloramine with sodium hypochlorite at pH 9.8–10.3, and reacted with thymol at pH 11.5–11.9 for 1 h, and the absorbance is measured at 660 nm. The proposed method was also used for the determination of nitrogen in titanium and uranium. Nitrogen in some other metals such as Al, Be, In, Mg, Mn, Si, Sb, Sn, Ta, V, W and Zn which can be fused with potassium hydroxide and have melting points above 400°C may also be determined.     

Microwave spectrum of CIS chlorine nitrite,CIONO

The metastable intermediate product, CIONO, which is formed from gaseous CINO and Cl₂O at about 203 K, has been detected by microwave spectroscopy. The rotational constants and the inertial defects for the ³⁵Cl and ³⁷Cl species establish that the observed spectrum is that of planar cis CIONO.     

Synthesis and metal binding properties of novel sulfur-containing functional oligomer

The synthesis and metal ion binding properties of a new class of functional oligomers are described. Oligo[1-(N-phenylthiocarbamoyl)aziridine] (DP ca. 8) and its analogs are prepared by ring-opening oligomerization of the corresponding aziridine monomers in good yields. These oligomers contain sulfur groups capable of binding “soft” metal ions, and the selective binding properties of the novel oligomer for Cu(II) and Hg(II) ions are investigated by liquid-solid adsorption and liquid-liquid extraction experiments.     

Memory of chirality in intramolecular conjugate addition of enolates: a novel access to nitrogen heterocycles with contiguous quaternary and tertiary stereocenters

Nitrogen heterocycles with contiguous quaternary and tertiary stereocenters have been prepared in high enantiomeric purity by intramolecular conjugate addition of enolates generated from alpha-amino acid derivatives via memory of chirality.     

Synthesis of Oligo(thienylfuran)s with Thiophene Rings at Both Ends and Their Structural,Electronic, and Field‐Effect Properties

Oligo(thienylfuran)s with thiophene rings at both ends ( SOSOSOS , DE‐SOSOS , DH‐SOSOS , DE‐SOSOSOS , and DH‐SOSOSOS ; S and O denote thiophene and furan rings, respectively, DE and DH denote diethyl‐ and dihexyl‐substituted, respectively) were newly synthesized by repetitive Stille coupling reactions. The UV/Vis maximum absorptions of the oligomers, SO , SOSO , SOSOS , SOSOSO , and SOSOSOS , exhibited a clear bathochromic shift with increasing number of heterocycles. The value of the oxidation peak potential (E_pa¹) determined by cyclic voltammetry decreased with an increase in the number of heterocycles by 0.06–0.08 V per heterocycle. The crystal‐packing structures of DE‐SOSOS and DH‐SOSOS determined by X‐ray crystallography have a herringbone motif and are denser than the reported structures of pentacene and α‐sexithiophene. The morphologies of thin films prepared by vacuum deposition and spin coating were investigated by atomic force microscopy and X‐ray diffraction. Among these films, those of DE‐SOSOS and DH‐SOSOS exhibited highly ordered arrangements. The devices based on vacuum‐deposited and spin‐coated films of DE‐SOSOS and DH‐SOSOS displayed the highest FET mobilities of 10^?2–10^?3 cm² V^?1 s^?1 among the oligomers reported in this study.     

Stereoselective iodine atom transfer [3 + 2] cycloaddition reaction with alkenes using unsymmetrical allylated active methine radicals

Treatment of 1-diethylphosphonyl- or 1-phenylsulfonyl-2-(iodomethyl)cyclopropane-1-carboxylate with Et(3)B leads to an unsymmetrical allylated active methine radical species that gives functionalized cyclopentane derivatives with high stereoselectivity through iodine atom transfer [3 + 2] cycloaddition reaction with alkenes.     

2‐Pyridone–tartronic acid (1/1), 3‐hydroxy­pyridinium hydrogen tartronate and 4‐hydroxy­pyridinium hydrogen tartronate

Tartronic acid forms a hydrogen‐bonded complex, C₅H₅NO·C₃H₄O₅, (I), with 2‐pyridone, while it forms acid salts, namely 3‐hydroxy­pyridinium hydrogen tartronate, (II), and 4‐hy­droxy­pyridinium hydrogen tartronate, (III), both C₅H₆NO⁺·C₃H₃O₅⁻, with 3‐hydroxy­pyridine and 4‐hydroxy­pyridine, respectively. In (I), the pyridone mol­ecules and the acid mol­ecules form R(8) and R(10) hydrogen‐bonded rings, respectively, around the inversion centres. In (II) and (III), the cations and anions are linked by N—H⋯O and O—H⋯O hydrogen bonds to form a hydrogen‐bonded chain. In each of (I), (II) and (III), an intermolecular hydrogen bond is formed between a carboxyl group and the hydroxyl group attached to the central C atom, and in (I), the hydroxyl group participates in an intramolecular hydrogen bond with a carbonyl group. No intermolecular hydrogen bond is formed between the carboxyl groups in (I), or between the carboxyl and carboxyl­ate groups in (II) and (III).     

Novel synthesis of N,N′‐dialkyl cyclic ureas using sulfur‐assisted carbonylation and oxidation

The first example of cyclic urea synthesis from secondary amines by the use of sulfur‐assisted carbonylation and oxidation was established. By combined sulfur‐assisted carbonylation of secondary α,ω‐diamines under an ambient pressure of carbon monoxide at 20°C with oxidation by molecular oxygen (0.1 MPa, 20°C), a facile synthetic method for N,N′‐dialkyl cyclic ureas including 1,3‐dimethyl‐2‐imidazolidinone was developed. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:64–68, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20508