AMPHIPHILIC STAR-BLOCK COPOLYMERS BY IODIDE-MEDIATED RADICAL POLYMERIZATION

Amphiphilic star-block copolymers composed of polystyrene and poly(acrylic acid)were synthesized by iodide- mediated radical polymerization.Firstly,free radical polymerization of styrene was carried out with AIBN as initiator and 1,1,1-trimethyolpropane tri(2-iodoisobutyrate)as chain transfer agent,giving iodine atom ended star-shaped polystyrene with three arm chains,R(polystyrene)_3.Secondly,tert-butyl acrylate was polymerization using polystyrene obtained as macro-chain transfer agent,and star-block copolymer,R(polystyrene-b-poly(tert-butyl acrylate))_3 with controlled molecular weight was obtained.Finally,amphiphilic star-block copolymer,R(polystyrene-b-poly(acrylic acid))_3 was obtained by hydrolysis of R(polystyrene-b-poly(tert-butyl acrylate))_3 under acidic condition.     

The Crystal Structure of Isosteviol

The title compound was prepared and its crystal structure was determined using X-ray crystallographic method. The crystal is orthorhombic, space group is P212121 with a= 1. 1114(2) nm, b=1.7677(3) nm, c=1.8312(3) nm; Z=8. The geometric structure and conformation of the title compound obtained by MMX molecular mechanics calculation are in agreement with those obtained from X-ray determination.     

Preparation of 1-Trifluoroethyl-4-methoxy-5-chloropyridazin-6-one: Methyl Shift of 4-Methoxy-5-chloropyridazin-6-one

N1-Trifluoroethyl-4-methoxy-5-chloro-3-pyridazone (4) was synthesized by the substitution reaction of 4methoxy-5-chloro-3-pyridazone (1) with trifluoroethyl trifluoromethanesulfonate (A) at basic condition. In the most of reaction conditions, N1-methyl-4-methoxy-5-chloro-3-pyridazone (2) was obtained as a major by-product, which means that the methyl group in the 4-methoxy shifted to N-1 position inter-molecularly aided by A or trifluoroethyl methanesulfonate (B). We obtained N1-methyl-4-trifluoro-ethoxy-5-chloro-3-pyridazone (3) in the reaction of 1 with B at higher temperature in different solvents with different yield (Table 1 ), which mechanism was shown in Figure 1. When we tried to synthesize 4 in the reaction of 1 with trifluoroethyl toluenesulfonate under basic condition, 6 was obtained (Figure 2). All the detailed mechanisms are undergoing investigated.     

Synthesis of γ-Substituted Alcohol with Polymer-bound Amide

With solid phase organic synthesis method(SPOS), polymer-bound N-enoylprolinol(4) was prepared by the attachment of N-enoylprolinol(3) to Merrifield resin and was used for asymmetric Michael additions for the first time. The enantiomeric excess obtained by this method is increased as compared with that obtained by the corresponding solution phase reactions.     

Cr^3^+的水解聚合作用IV.两种"根+节"体系之间的过渡状态

The hydrolytic polymerization of chromium (III) ion in 0.040, 0.060, 0.080 and 0.160M Cr(NO3)3 solutions was studied pH-metrically in the medium of 0.5M NaNO3 at 40+/-1 C. The average number of OH- bound per Cr^3^+ at different pH was designated as Z, the gighest value of Z was found to be about 1.0. A family of curves of Z(pH)B, each at a definite concentration B of Cr(NO3)3, was obtained. The values of both B and pH were determined from the curves and a linear relationship between -lgB and pH was found for each value of Z. From the slope of each curve of-lgB(pH)z, a value of t was obtained, which increased from 1.51 to 2.06 when Z increased from 0.10 to 1.0. This implied that the polymerized hudrolysis products were of mixed types. The data of different Z value were treated by three different methods, namely, "core + links" method, project strip method and "homoligand formation constant" method. The results obtained showed the existence of "core + links" compounds not only with two hydroxyl bridges as Cr (Cr(OH)2)n^(^3^+^n^)^+(n = 1,2,3) but also with both one and two hydroxy bridges as Cr3(OH)3, indicating that the present system was a transition from t = 2 to t = 1. The hydrolysis constants of the above compounds are as follows: lgβ = -4.19, lgβ33 = -5.28, lgβ = -8.23, lgβ64 = 12.28. The above results are in agreement with those obtained at low and medium concentration of Cr(NO3)3. Furthermore, the constants obtained by means of different methods are in good agreement with each other as well as with those reported in previous papers.     

POLYMERIZATION OF γ-STEARYL-α,l-GLUTAMATE N-CARBOXYANHYDRIDE USING RARE EARTH COORDINATION CATALYSTS*

A rare earth coordination system was first investigated as a new type of catalyst for the ring-openingpolymerization of α-amino acid N-carboxyanhydrides (NCAs). The results for the polymerization of γ-stearyl-α,L-glutamate(SLG) NCA using neodymium acetylacetonate (Nd(acac)_3)- or neodymium tris(2-ethylhexylphosphonate) (Nd(P_(204))_3)-triethylaluminum-water as catalysts were compared with those using conventional catalysts. It was found that the helicalpoly(γ-stearyl-L-glutamate) with high molecular weight as well as narrow molecular weight distribution can be obtained inthe presence of Nd(acac)_3/AlEt_3-1/2H_2O. The polymer obtained was characterized by IR and NMR spectroscopy.     

Synthesis via Precursor Method and Shape Evolution of Basic Magnesium Carbonate

Basic magnesium carbonate(4 MgCO3·Mg(OH)2·4 H2 O) with spherical-like structure was synthesized through precursors thermal decomposition. The precursor of magnesium carbonate trihydrates(MgCO3·3 H2 O) was synthesized by brine and ammonium bicarbonate, and the thermal decomposition conditions were investigated in detail. The obtained particulate was characterized using SEM, XRD and laser particle analyzer. The result showed that it was easy to obtain spherical-like 4 MgCO3·Mg(OH)2·4 H2 O by precursor thermal decomposition at 80~100 ℃ with thermal decomposition time 90 min, stirring time 15 min and the liquid initial concentration 0.1 mol/L, while rod-like 4 MgCO3·Mg(OH)2·4 H2 O with a surface of "house of card" structure was more likely to be obtained at low temperature(55 ℃), and rosette-like products were obtained at a little higher temperature(80 ℃) by direct synthesis.     

Molecular Docking and 3D-QSAR Research of Biphenyl Carboxylic Acid MMP-3 Inhibitors

The molecular docking by LigandFit docking of Discovery Studios 2.5 was employed to the three-dimensional quantitative structure-activity relationship(3D-QSAR) studies of biphenyl carboxylic acid MMP3 inhibitors.A significant correlation coefficient was obtained between dock scores and biological activities.Based on the optimal docking conformations,3D-HoVAIF was employed to the QSAR studies of 51 biphenyl carboxylic acid MMP-3 inhibitors.R2 and Q_CV2(leave-one-out,LOO) of the optimal 3D-HoVAIF-PLS model were 0.873 and 0.841 respectively.The conclusions obtained from the PLS analysis were in agreement with the docking results.     

SYNTHESIS AND STRUCTURE OF A MIXED-VALENCE HEXAMOLYBDENUM COMPLEX [Et_4N]_2[Mo_6O_(19)H_4]

A hexamolybdenum complex, [Et_4N]_2[Mo_6O_(19)H_4] crystal, withpentavalent and hexavalent molybdenum has been obtained in the solution ofDMF and CH_3OH as organic solvents using MoCl_5 as a starting material. Thecrystallographic parameters obtained by X-ray diffraction analysis are:crthorhombic, a=10. 757(3), b=10. 763(2), c=14. 238(4)A, =1648. 9A~3; Z=2; spacegroup Pnnm; final R=0. 047; final Rw=0. 051~(**)     

Efficient synthesis of 4(3H)-quinazolinones using a soluble polymeric support

4(3H)-Quinazolinones have been synthesized from poly(ethylene glycol)(PEG)supported aza-Wiuig reaction.2-Dialkylamino- 4(3H)-quinazolinones 6 were synthesized efficiently by reaction of secondary amine with PEG-supported carbodiimides 4,which were obtained from aza-Wittig reaction of PEG-supported iminophosphoranes 3 with isocyanates.     

Synthesis of 3-(2-Aryloxazolidin-3-yl)tropanes

We obtained 3-(2-aryloxazolidin-3-yl)tropanes by reaction of aromatic aldehydes with 3-[N-(2-hydroxyethyl)amino]tropane. We obtained 3-benzyloxazolidine-2-spiro-3'-(8'-carbethoxy)nortropane by reaction of benzylaminoethanol with 8-carbethoxynortropan-3-one.     

天然产物Combretastatin A-1和Combretastatin B-1的合成

基于Perkin反应策略合成了具有强效抗肿瘤、抗血管活性的天然产物Combretastatin A-1(CA1)和Combretastatin B-1(CB1).以2,3,4-三羟基苯甲醛(1)为起始物, 经单甲基化反应得到2,3-二羟基-4-甲氧基苯甲醛(2), 再经酚羟基保护得到2,3-二异丙基-4-甲氧基苯甲醛(3), 该化合物与3,4,5-三甲氧基苯乙酸(4)发生Perkin反应分离得到E-2-(3,4,5-三甲氧基苯基)-3-(2',3'-二异丙氧基-4'-甲氧基)丙烯酸(E-5), 经脱羧反应得到Z-3,4,4',5-四甲氧基-2',3'-二异丙氧基二苯乙烯(6), 最后经脱保护反应得到CA1.另外, 将E-2-(3,4,5-三甲氧基苯基)-3-(2',3'-二异丙氧基-4'-甲氧基)丙烯酸(E-5)脱去保护基得到E-2-(3,4,5-三甲氧基苯基)-3-(2',3'-二羟基-4'-甲氧基)丙烯酸(7), 该化合物经脱羧-异构化反应得到E-3,4,4',5-四甲氧基-2',3'-二羟基二苯乙烯(E-CA1), 最后经催化氢化得到CB1.     

均分散球形氧化铕超细微粒的制备和表征

采用尿素分解法制备了均分散球形Eu(OH)CO~3·H~2O超细沉淀粒子,进一步在空气中750℃下焙烧4h,得到了均分散球形氧化铕超细微粒。考察了各种反应条件的影响,获得了最佳的制备条件。用XRD,IR,TEM,TG以及比表面测定等手段对样品进行了表征。     

Benzofuran derivatives. Part 3 On the reactivities of the intermediates in benzofuran synthesis

3-Methyl-5-nitrobenzofuran ( 2 ) and 3-methyl-5-nitrobenzofuran-2-carboxylic acid ( 3 ) were obtained by heating 2-acetyl-4-nitrophenoxyacetic acid ( 1 ) with various bases in acetic anhydride. It appeared that 3-hydroxy-3-methyl-5-nitro-2,3-dihydrobenzofuran-2-carboxylic acid ( 4 ) was the intermediate in the benzofuran synthesis. The properties of 4 were examined under various conditions. Using strong bases such as triethyl-amine in place of sodium acetate, 3-methyl-5-nitrobenzofuran-2-carboxylic acid ( 3 ) was obtained exclusively. However, in the presence of acetic acid in the reaction mixture 3-methyl-5-nitrobenzofuran ( 2 ) was obtained in good yield. The reaction pathways for the formation of 2 and 3 are discussed.     

Fluorescence properties of Nd3+-doped tellurite glasses

The compositional and concentration dependence of luminescence of the (4)F(3/2)-->(4)I(J) (J=13/2, 11/2 and 9/2) transitions in four Nd(3+)-doped tellurite based glasses has been studied. The free-ion energy levels obtained for 60TeO(2)+39ZnO(2)+1.0Nd(2)O(3) (TZN10) glass have been analysed using the free-ion Hamiltonian model and compared with similar results obtained for Nd(3+):glass systems. The absorption spectrum of TZN10 glass has been analysed using the Judd-Ofelt theory. Relatively longer decay rates have been obtained for Nd(3+)-doped phosphotellurite glasses. The emission characteristics of the (4)F(3/2)-->(4)I(11/2) transition, of the Nd(3+):TZN10 glass, are found to be comparable to those obtained for Nd(3+):phosphate laser glasses. The non-exponential shape of the emission decay curves for the (4)F(3/2)-->(4)I(11/2) transition is attributed to the presence of energy transfer processes between the Nd(3+) ions.     

Removal of the potent greenhouse gas NF3 by reactions with the atmospheric oxidants O(1D), OH and O3

Nitrogen trifluoride, NF(3), a trace gas of purely anthropogenic origin with a large global warming potential is accumulating in the Earth's atmosphere. Large uncertainties are however associated with its atmospheric removal rate. In this work, experimental and theoretical kinetic tools were used to study the reactions of NF(3) with three of the principal gas-phase atmospheric oxidants: O((1)D), OH and O(3). For reaction (R2) with O((1)D), rate coefficients of k(2)(212-356 K) = (2.0 ± 0.3) × 10(-11) cm(3) molecule(-1) s(-1) were obtained in direct competitive kinetics experiments, and experimental and theoretical evidence was obtained for F-atom product formation. These results indicate that whilst photolysis in the stratosphere remains the principal fate of NF(3), reaction with O((1)D) is significant and was previously underestimated in atmospheric lifetime calculations. Experimental evidence of F-atom production from 248 nm photolysis of NF(3) was also obtained, indicating that quantum yields for NF(3) destruction remain significant throughout the UV. No evidence was found for reaction (R3) of NF(3) with OH indicating that this process makes little or no contribution to NF(3) removal from the atmosphere. An upper-limit of k(3)(298 K) < 4 × 10(-16) cm(3) molecule(-1) s(-1) was obtained experimentally; theoretical analysis suggests that the true rate coefficient is more than ten orders of magnitude smaller. An upper-limit of k(4)(296 K) < 3 × 10(-25) cm(3) molecule(-1) s(-1) was obtained in experiments to investigate O(3) + NF(3) (R4). Altogether these results underpin calculations of a long (several hundred year) lifetime for NF(3). In the course of this work rate coefficients (in units of 10(-11) cm(3) molecule(-1) s(-1)) for removal of O((1)D) by n-C(5)H(12), k(6) = (50 ± 5) and by N(2), k(7) = (3.1 ± 0.2) were obtained. Uncertainties quoted throughout are 2σ precision only.     

Indole derivatives

5-(3-Indolylmethyl)barbituric and 5-(3-indolylmethyl)thiobarbituric acids were obtained by condensation of 3-indolylmethylmalonic ester with urea and thiourea in monoglyme (1,2-di-methoxyethane) in the presence of lithium methoxide. The first of the two acids was also obtained by catalytic hydrogenation of 5- (3-indolylmethylene)barbituric acid.     

四乙基二氟化氢铵催化的基团转移聚合

用三种引发剂进行了二氟化氢负离子催化的基团转移聚合,得到了窄分布的,实测分子量和理论分子量相近的一系列聚甲基丙烯酸酯产物,合成了分子量达20万以上的聚甲基丙烯酸甲酯,探讨了引发剂和催化剂用量对产物的分子量和分散性的影响,认为过量的催化剂使产物的分散性加大和实测(?)_n大于理论M_n。得到了控制聚合的最佳催化剂和引发剂浓度比。     

Large-scale synthesis of tungsten oxide nanofibers by electrospinning

We show in this communication that large-scale synthesis of orthorhombic WO3 nanofibers can be obtained via a simple electrospinning method. The morphology and the crystal structure are investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), FTIR, X-ray diffraction patterns (XRD) and X-ray photoelectron spectra (XPS) spectra. SEM and TEM images showed that the diameter of the obtained WO3 nanofibers is between 100 and 500 nm. The structure of the obtained WO3 nanofibers was characterized by FTIR, XRD, and XPS spectra. The photoluminescence of the obtained WO3 nanofibers were also investigated.     

Neuartige Merocyanine vom Typ des «Bindons»

The title compounds (new type of merocyanines) were obtained from the reaction of heterocyclic enamines with indan-1,3-dione, biindantrione, 2-(3-methoxy-inden-1-yliden)-indan-1, 3-dione, or 2-(3-chloro-inden-1-yliden)-indan-1, 3-dione respectively. The enamines were obtained from the corresponding quaternary salts and reacted in situ.