Novel fluorinated hybrid polymer preparation from silsesquioxanes by radical polyaddition

Radical polyaddition of bis(α-trifluoromethyl-β,β-difluorovinyl) terephthalate [CF₂C(CF₃)OCOC₆H₄COOC(CF₃)CF₂] (BFP) with silsesquioxanes was investigated in order to produce a polymer possessing silsesquioxane moiety in polymer main chain. 1,3,5,7,9,11,13,15-octakis(dimethylsilyloxy)pentacyclo[9.5.1.1^3,9.1^5,15.17,13]octasiloxane (T₈S) with BFP successfully afforded a polymer bearing a molecular weight of about 2.5×10⁵. The polymer obtained were soluble in usual organic solvent such as methanol, tetrahydrofuran and chloroform. In order to get some information on the polyaddition reaction mechanism, model reactions of 2-benzoxypentafluoropropene [CF₂C(CF₃)OCOC₆H₅] (BPFP) with dimethylphenylsilane, [(CH₃)₂SiHC₆H₅], BPFP with 1,1,3,3-tetramethyldisiloxane {[(CH₃)₂SiH]₂O}, and BFP with dimethylphenylsilane were carried out. The mechanism that the radical abstracts a hydrogen from silane compounds followed by the addition of perfluoroisopropenyl groups was proposed.     

Electrochemically aided solid phase microextraction: conducting polymer film material applicable for cationic analytes

The cation uptake and release properties of a poly(pyrrole-sulfated β-cyclodextrin) (PPy-SβCD) film electrode have been investigated under both open circuit and controlled potential conditions for prospective applications in electrochemically aided solid-phase microextraction (EA SPME). The EDAX and ion chromatography results show that the K⁺ and Na⁺ cation uptake is enhanced if a small negative potential is applied to the electrode in the range where PPy is in its neutral form. These cations are released rapidly from the film if the applied potential is switched to the value at which PPy is converted to its positively charged form, i.e., oxidized state. The cation ingress and egress mechanism is affected both by the cation exchange at the negative sulfate moiety on the cyclodextrin sites and electrostatic interactions generated by the applied potential. The electrochemical "switching" capability increases the speed of the cation uptake and release, presumably due to electro migration, as compared to the open circuit ion exchange which is controlled solely by diffusion. Our preliminary fundamental results show that the PPy-SβCD film is suitable for the future design of EA SPME devices. Electronic Publication     

Vinyl polymerization of norbornene catalyzed by a series of bis(β-ketoiminato)nickel (II) complexes in the presence of methylaluminoxane

A series of nickel complexes with β-ketoiminato ligands based on pyrazolone derivative were synthesized and characterized, which are highly active catalyst precursors for norbornene polymerization under mild reaction conditions through a vinyl-type polymerization mechanism. The catalytic activity could be up to 3.38 × 10⁷ g polymer/mol Ni h. The molecular weight distributions of the polynorbornenes (M_w/M_n = 2.05-2.56) indicate the presence of a single active species in the polymerization process.     

Complex Formation Between Alkane-α,ω-Diols and Cyclodextrins Studied by Partial Molar Volume and Compressibility Measurements

The binding of a series of alkane-,-diols, HO(CH₂)_nOH, n = 4 to 7, to - and -cyclodextrin (CD) has been studied by measurements of partial molar volumes (PMVs) and isentropic partial molar compressibilities (PMCs) at 25°C. From the PMV and PMC data, changes in the partial molar quantities upon going from a free state in aqueous solution to a complexed state were evaluated for the diols. Negative changes in PMV and PMC were observed for complex formation with -CD, while positive values were obtained for the -CD complexes. Equilibrium constants for the different complexes, assuming the formation of 1:1 complexes, were evaluated from the PMV and/or PMC data, and were found to increase with increasing chain length of the included diol for both - and -CD complexes. The equilibrium constant for complex formation is generally higher for the -CD than for the -CD complexes.     

Microwave-assisted InCl3-catalyzed Meyer-Schuster rearrangement of propargylic aryl carbinols in aqueous media: a green approach to α,β-unsaturated carbonyl compounds

A novel, efficient, simple and environmentally benign protocol for the Meyer-Schuster isomerization of propargylic aryl carbinols into α,β-unsaturated carbonyl compounds has been developed using catalytic amounts of InCl₃, pure water as the solvent, and microwave irradiation as the heating source.     

Experimental and Theoretical Study on the Inclusion Capability of a Fluorescent Indolizine β-Cyclodextrin Sensor Towards Volatile and Semi-volatile Organic Guest

Inclusion equilibria of a new fluorescent indolizine modified β-cyclodextrin were studied in aqueous solution to evaluate its use as a fluorescent chemo-sensor for volatile organic compounds (VOCs). The host compound shows a decrease of the fluorescence intensity by adding adamantanol, benzene, toluene, phenol and p-cresol as guest. The sensing parameter (ΔI/I ₀) was used to show the sensing ability of the host. The formation constant values measured using a spectral displacement method and a specific algorithm treatment are reported. Although the guest binding ability of the sensor is not enhanced by the existence of the hydrophobic cap, this new cyclodextrin sensor shows a very strong sensing ability. The experimental values of the constants were in good agreement with the computed complexation energies, ΔE, from molecular mechanics modelling of the inclusion process.     

四氢β-咔啉类化合物的13C NMR研究

测定了四对新合成的四氢β-咔啉化合物的¹³C NMR谱,通过APT、HETCOR和HETCOLOC谱指认了所有碳的归属.所确定的化学位移规律可以用来确定它们的构型.     

The reaction of hydroxylamine with aryl trifluoromethyl-β-diketones: Synthesis of 5-hydroxy-5-trifluoromethyl-Δ-isoxazolines and their dehydration to 5-trifluoromethylisoxazoles

Reaction of hydroxylamine hydrochloride with aryl trifluoromethyl-β-diketones affords 5-hydroxy-5-trifluoromethyl-Δ²-isoxazolines rather than the reported 3-trifluoromethylisoxazoles. The structural assignment is based on the analysis of their NMR (¹H, ¹³C and ¹⁹F) spectral data and of their dehydration products, 5-trifluoromethylisoxazoles.     

β-烷氧羰乙撑基三氯化锡与N-芳基-2-羟基乙酰苯叉亚胺配合物的NMR谱与结构

测定了12个新合成的有机锡-Schiff碱配合物的¹H NMR谱和¹³C NMR谱,详细研究了化合物结构与NMR谱的关系,通过比较配体和配合物的NMR谱,得出配合物是通过酚羟基氧原子和锡原子的配键生成的.     

N—（β—羟乙基）乙二胺三乙酸锑的晶体结构

近年来锑配位化合物的晶体结构已有多篇报道,并探讨了这类化合物的结构在其抗肿瘤活性中的地位。本文报道N-(β-羟乙基)乙二胺三乙酸锑的晶体结构。 结果与讨论 N-(β-羟乙基)乙二胺三乙酸锑(C_(10)H_(15)O_7N_2Sb)为无色透明棱形片状晶体,20℃时密度ρο=1.82g/cm~3,实测值(理论值):Sb 30.2(30.7),C 30.0(30.3),H 3.9(3.8),N 6.8(7.1)。