新型感可见光的染料鎓盐光引发体系

本文报道了一种新型感可见光的引发体系-曙红双(二苯基碘鎓盐)(Eo(IPh_2)_2).在基态,这种体系具有良好的热稳定性,而在激发态时能发生离子对内光诱导电子转移反应,导致其发生漂白和碘鎓盐的分解反应,产生具有引发作用的自由基.该体系适用于一般烯类单体的自由基聚合,其中时丙烯酸酯类单体效果最好.在以甲基丙烯酯甲酯(MMA)为单体时,聚合反应速度满足动力学方程:R_p=l[Eo(IPh_2)_2]~(0.38)[MMA],并求得聚合反应的活化能E_c=7.00kcal/mol.氧在Eo(IPh_2)_2光敏引发聚合中,既起自由基聚合阻聚剂的作用,又起引发剂三重态猝灭剂作用     

笼形聚肟偕亚氨二乙酸钒(Ⅳ)-硫脲体系引发丙烯腈聚合的研究

 研究了笼形聚肟偕亚氨二乙酸钒(CPV)-硫脲(TU)体系在硝酸溶液中引发丙烯腈(AN)聚合反应.表观聚合速度(R_P)是 R_P=1.0×10⁸e(-10.500/RT)[AN]^1.0[CPV]^1.0[TU]^1.5[HNO₃]^3.0 聚合诱导期(τ)随反应温度和物料浓度发生变化,可表示为 1/τ=5.2×10⁹e^-12.800/RT[AN]^1.0[CPV]^1.0[TU]^1.5[HNO₃]^3.0实验结果表明,聚合反应以单基终止为特征,可能是和高分子载体较大的空间位阻有关.     

金属卡宾模板导向的多咪唑鎓盐大环合成

本文报道了一种共价有机大环化合物的高效合成方法。利用双咪唑鎓盐H₂-L1(BF₄)₂(L1=A1,B1)和氧化银反应,生成双核银卡宾大环化合物[Ag₂(L1)₂](BF₄)₂(L1=A1,B1),其中连接在2个卡宾配体上的端烯取代基分别排列在环的两侧。随后,通过金属卡宾模板导向的烯烃复分解反应进行关环,制备得到闭环的双核银卡宾大环化合物[Ag₂(L2)](BF₄)₂(L2=A2,B2)。最后,移除模板银离子即可得到拥有空腔结构的共价有机大环化合物H₄-L2(BF₄)₄(L2=A2,B2)。此类多咪唑鎓盐大环的尺寸和形状可以通过改变氮杂环卡宾前驱体连接单元的长度或者宽度进行精细调节。初步研究表明,该大环受体在碘离子的传感、检测和识别方面具有潜在的应用前景。     

苯氧铜/正丁基锂体系引发MMA负离子聚合及其活性特征的研究

采用苯氧铜/正丁基锂(PhOCu/n-BuLi)体系引发MMA聚合, 通过GPC, ¹H NMR对聚合物进行了表征. 实验结果表明, 该体系聚合反应速度较快, 温度、引发体系组成是影响聚合物分子量及其分布、单体转化率、引发剂引发效率、聚合物的立构规整性的主要因素; －40 ℃时分子量分布比较窄, 但引发效率也比较低(大约15%). 低引发效率、宽分子量分布与引发剂的聚集状态有关. 分子量与单体浓度、引发剂浓度的关系说明, 该体系具有一定程度的活性聚合特点.     

HCF(X~1A’)+SO2反应的动力学研究

用激光光解-激光诱导荧光方法研究了室温下(T＝293 K) HCF(X^~1A^’)自由基与SO₂分子的反应动力学. 实验中HCF(X^~1A^’)自由基是由213 nm激光光解HCFBr₂产生的, 用激光诱导荧光(LIF)检测HCF(X^~1A^’)自由基的相对浓度随着反应时间的变化, 得到此反应的二级反应速率常数为: k＝(1.81±0.15)×10^－12 cm³•molecule^－1•s^－1, 体系总压为1862 Pa. 高精度理论计算表明, HCF(X^~1A^’)和SO₂分子反应的机理是典型的加成-消除反应. 我们运用RRKM-TST理论计算了此二级反应速率常数的温度效应和压力效应, 计算结果和室温下测定的二级反应速率常数符合得较好.     

氧桥双β-二亚胺钴配合物的合成及结构

Treatment of the lithium β-diketiminate [Li{N(R)C(NMe₂)C(H)C(NMe₂)N(R)}]₂ (1) (R=SiMe₃) with KOBu^t, KOH·H₂O and CoCl₂ in tetrahydrofuran gave in good yields the RO bridged β-diketiminato Co(Ⅱ) complex [Co{N(H)C(NMe₂)C(H)C(NMe₂)N(R)-( μ-OR)}]₂ (2) at ambient condition. The crystal data of (2) are as follows: crystal system, monoclinic; space group, P121/n1; a=0.963 9(3) nm, b=1.077 2(3) nm, c=2.025 0(6) nm, V=2.102 5(10) nm³, Z=2, D_c=1.186 g·cm^-3, F(000)=804, μ(Mo Kα)=0.934 mm^-1, R₁=0.047 8, wR₂=0.097 9. In solid state, complex (2) is a dimer bridged by RO (R=SiMe₃) group and the two Co²⁺ are in distorted tetrahedron. CCDC: 249253.     

阳离子(从有机铵到无机阳离子)对fac-[Fe(CO)3I3]-阴离子的稳定性和毒性的调节

通过无机碘盐(MI_n)与 cis-[Fe(CO)₄I₂]反应制备了 5 个盐类化合物 fac-M[Fe(CO)₃I₃]_n (Mⁿ⁺=Na⁺ (1),K⁺ (2),Mg²⁺ (3),Ca²⁺ (4),NH₄⁺ (5)),探讨了阳离子Mⁿ⁺对fac-[Fe(CO)₃I₃]^-阴离子的稳定性和细胞毒性的影响。通过傅里叶变换红外光谱(FTIR)监测,发现盐 1~5在 DMSO、D₂O、生理盐水等介质中均能缓释 CO,其释放动力学符合一级反应动力学模型;还发现溶液中碘离子的浓度和酸度对该阴离子的缓释CO性能也具有调节作用。通过噻唑蓝(MTT)实验评估了盐1~5对膀胱癌细胞的毒性,其24 h半抑制浓度(IC₅₀)在 25~43 μmol·L^-1。与有机铵阳离子类的盐化合物相比,盐1~5在含水介质中的释放 CO速率下降,毒性亦有下调。研究还发现这类fac-[Fe(CO)₃I₃]^-阴离子在缓释CO的同时释放碘自由基,并能导致线粒体活性氧(ROS)水平、Parkin蛋白表达均上调。铁死亡抑制剂(Ferrostatin-1和Liproxstatin-1)试验结果表明这类化合物可能引发铁死亡通路并促进肿瘤细胞死亡。     

4-(4′-二甲胺基苯乙烯基)-二苯酮/二苯基碘鎓盐——一种新的电子转移光敏化聚合引发体系

一种新的光敏剂,4-(4′-二甲胺基苯乙烯基)-二苯酮(MABP),已经合成并作了光谱特性表征,MABP和二苯基碘鎓盐(DPIO)组成的体系在近紫外和可见光区具有良好的光响应性,MABP和DPIO体系的光解反应通过电子转移过程快速发生,同时产生MABP的光褪色反应和DPIO的裂解反应,生成具有引发作用的苯自由基,MABP的光褪色速度常数测定为30.7(mol^-1·L·s^-1),甲基丙烯酸甲酯(MMA)的光聚合反应在氮气净化的乙腈溶液中进行,得到的动力学数据表明,聚合速度和MABP,DPIO和MMA的浓度成正比,浓度指数值分别为0.46,0.32和1.0,添加巯基化合物显著地加速聚合反应,光引发机理也作了讨论。     

新型的含硫族元素碳硼烷配体的三(3，5-二甲基-1-吡唑)硼氢钼配合物的合成和分子结构(英)

三齿单核三(3，5-二甲基-1-吡唑)硼氢钼配合物Tp^*Mo(O)Cl₂ (1)(Tp^*=三(3，5-二甲基-1-吡唑)硼氢HB(C₃H(Me₂)N₂)₃)与含硫族元素碳硼烷的锂盐[(THF)₂LiE₂C₂B₁₀H₁₀(THF)]<     

阳离子(从有机铵到无机阳离子)对fac-[Fe(CO)3I3]-阴离子的稳定性和毒性的调节

通过无机碘盐(MI_n)与cis-[Fe (CO)₄I₂]反应制备了5个盐类化合物fac-M[Fe (CO)₃I₃]_n(Mⁿ⁺=Na⁺(1),K⁺(2),Mg²⁺(3),Ca²⁺(4),NH⁴⁺(5)),探讨了阳离子Mⁿ⁺对fac-[Fe (CO)₃I₃]^-阴离子的稳定性和细胞毒性的影响。通过傅里叶变换红外光谱(FTIR)监测,发现盐1~5在DMSO、D₂O、生理盐水等介质中均能缓释CO,其释放动力学符合一级反应动力学模型;还发现溶液中碘离子的浓度和酸度对该阴离子的缓释CO性能也具有调节作用。通过噻唑蓝(MTT)实验评估了盐1~5对膀胱癌细胞的毒性,其24 h半抑制浓度(IC₅₀)在25~43 μmol·L^-1。与有机铵阳离子类的盐化合物相比,盐1~5在含水介质中的释放CO速率下降,毒性亦有下调。研究还发现这类fac-[Fe (CO)₃I₃]^-阴离子在缓释CO的同时释放碘自由基,并能导致线粒体活性氧(ROS)水平、Parkin蛋白表达均上调。铁死亡抑制剂(Ferrostatin-1和Liproxstatin-1)试验结果表明这类化合物可能引发铁死亡通路并促进肿瘤细胞死亡。     

Cyclopentadienyl(iron)arene-bis-(p-N,N-dimethylaminobenzylidene)-cyclopentanone Photoinitiated Polymerization of Methyl Methacrylate and Styrene

Abstract

Polymerization of methyl methacrylate and styrene can be effectively photoinitiated by a binary photoinitiator system consisting of cyclopentadienyl(iron)arene hexafluorophosphonate salt and bis(p-N, N-dimethylaminobenzylidene)cyclopentanone in the spectral range of 400–500 nm. The amine-type radical formed from the exciplex of the binary photoinitiator system is probably responsible for the radical polymerization of vinyl monomers. A probable mechanism of initiation of polymerization is discussed.     

Propenyl ethers. III. Study of the photoinitiated cationic polymerization of propenyl ether monomers

The effects of photoinitiator structure and variations in the experimental parameters on the rate and extent of the photoinitiated cationic polymerization of propenyl ether monomers were studied. It was found that the photoinitiators can be divided into two classes: those which exhibit an induction period and those which do not. It was demonstrated that in those propenyl ether polymerizations using iodonium salts and certain sulfonium salts which do not have an induction period, a free radical chain-induced decomposition of the onium salt takes place. The reactivity of a particular onium salt photoinitiator was shown to be related to its reduction potential. It was also shown that the structure of the monomer plays a major role in the free radical induced decomposition reaction. © 1993 John Wiley & Sons, Inc.     

丙烯酸酯/环氧的自由基/阳离子同步光聚合混合体系的研究

科学技术的进步,对新材料的要求逐步向着多功能和高性能的方向发展,单组分材料已难于满足这种要求,在高分子材料方面,人们采用了共混、接枝、嵌段等方法以达到改善和提高性能的目的。感光性高分子是一类很重要的功能材料,至今,大部分采用自由基聚合方式制备。近年来,阳离子引发体系发展很快,特别鎓盐光引发体系受到很大的重视,发展迅速。     

A new visible light sensitive photoinitiator system for the cationic polymerization of epoxides

This communication reports the development of an efficient three‐component visible light sensitive photoinitiator system for the cationic ring‐opening photopolymerization of epoxide monomers and epoxide functional oligomers. The photoinitiator system consists of camphorquinone in combination with a benzyl alcohol to generate free radicals by the absorption of visible light. Subsequently, the radicals participate in the free radical chain induced decomposition of a diaryliodonium salt. The resulting strong Brønsted acid derived from this process catalyzes the cationic ring‐opening polymerization of a variety of epoxide substrates. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 866–875, 2009     

Photopolymerization of Methyl Methacrylate and other Acrylates with the Use of [Hydroxy(tosyloxy)iodo]benzene as Photoinitiator

Abstract

[Hydroxy(tosyloxy)iodo]benzene (HTIB) was found to be an effective photoinitiator for the solution polymerization of methyl methacrylate. The polymerization is strongly inhibited in the presence of hydroquinone, it is not affected by air, and it is favored in the presence of nucleophilic solvents. A kinetic study of solution polymerization in N,N-dimethylformamide indicated a free radical polymerization mechanism involving complexation of initiator molecules with the solvent prior to radical generation, and bimolecular termination of chain radicals. Methyl acrylate and 2-hydroxyethyl methacrylate were also polymerized with HTIB as photoinitiator, but styrene could not be polymerized under similar conditions.     

Radical-Promoted Visible Light Photoinitiated Cationic Polymerization of Epoxides

Herein is described the development of a three-component photoinitiator system that employs the free radical promoted decomposition of diaryliodonium salts for the visible light induced cationic polymerization of epoxides. A long wavelength, titanium-complex free radical photoinitiator is used to generate radicals that abstract hydrogen atoms from benzyl alcohol synergists. The resulting benzyl radical species efficiently reduce diaryliodonium salts thereby generating oxycarbenium ions that spontaneously fragment to form the corresponding aldehyde and a Br?nsted superacid. The superacid subsequently initiates the cationic ring-opening polymerization of a wide variety of epoxide monomers.     

光引发阳离子聚合反应的研究——Ⅱ.硫鎓盐DPTS引发乙烯基正丁醚光聚合动力学

以二苯基-4-苯硫基代苯基硫鎓盐(DPTS)为光引发剂,研究了乙烯基正丁醚的本体和溶液光聚合。在本体聚合中,聚合速率(R_p)与引发剂浓度成正比;在15～35℃范围内,聚合活化能几乎为零。分别以CHCl₃(CH₂Cl)₂和C₆H₅Cl作溶剂的溶液聚合,其R_p均比本体聚合者大,同时单体浓度对R_p的影响则表现出复杂的关系。根据普遍接受的硫鎓盐光解机理并假设溶剂和单体均可不同程度地参与引发反应,解释了溶液聚合中单体影响的动力学规律。     

4-N,N-Dimethylamino-4'-Isopropylbenzophenone as polymerization photoinitiator. Effect of solvent and photoinitiator concentration on its photoreactivity and on the polymerization process

Several kinetics aspects of the methyl methacrylate (MMA) polymerization using 4-dimethylamino-4'-isopropylbenzophenone (PI) as photoinitiator have been studied. The order of the polymerization reaction with respect to monomer and initiator concentrations have been investigated, as well as the polymerization behavior under well-stirred and unstirred conditions; values of initiation quantum yield (?_i) and k_p/k_t^1/2 have also been determined. It has been found that the nature of the polymerization-initiating radicals depends on the type of solvent and the photoinitiator concentration ([PI]). In cyclohexane solution and at low [PI] (< 5 x 10^-5M), the cyclohexyl radical is practically the only polymerization initiating radical, while at higher [PI] both radicals, cyclohexyl and the aminoalkyl derived from PI, participate in the initiation step, increasing the participation of the later as the [PI] increases. When benzene is used as solvent both phenyl and aminoalkyl radicals participate in the initiation step at any [PI] employed. Efficiencies of the radicals derived from solvent and photoinitiator have been determined.     

The synthesis and cationic photopolymerization of monomers based on dicyclopentadiene

Several new epoxide monomers based on dicyclopentadiene (DCPD) were prepared using straightforward reaction chemistry. Those monomer-bearing groups in addition to the epoxy moiety, which can stabilize free radicals, display a pronounced acceleration of the rate of cationic ring-opening polymerization in the presence of diaryliodonium salt photoinitiators. Mechanistic studies conducted with the aid of model compounds have shown that the apparent rate acceleration is due to the free radical chain-induced decomposition of the photoinitiator. One of the chain carriers in this reaction involves a monomer-derived free radical. Also prepared was dicyclopentadiene monomer (V) bearing polymerizable epoxide and 1-propenyl ether groups in the same molecule. The functional groups in V appear to undergo independent vinyl and epoxide ring-opening polymerization. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3427–3440, 1999