基于2，5-二溴对苯二甲酸配体的锰/钴配合物的合成、晶体结构及性质

将有机物2,5-二溴对苯二甲酸(H₂L₁)作为主配体,2,2′-联吡啶(L₂)、1,10-菲咯啉(L₃)分别作为辅配体,通过溶剂热法与一水硫酸锰、六水合硝酸钴分别反应得到配合物[Mn₂(L₁)₂(L₂)₂(H₂O)₂]_n (1)和[Co₂(L₁)₂(L₃)₂(H₂O)₂]_n(2)。通过单晶X射线衍射法、荧光光谱、热重分析等测试手段对这2种配合物进行分析研究。结果表明配合物1是由Mn²⁺配位连接L₁^2-与L₂形成无限延伸的二维网络状结构,各层在分子间氢键和π-π堆积作用...     

带有苯酚侧臂的四氮大环Zn(Ⅱ)配合物催化羧酸酯水解研究

合成并表征了在大环侧臂引入取代苯酚作为功能基团的新型四氮大环配体(L₁,L₂和L₃).对配体L₃的质子化过程及其与Zn(Ⅱ)的配位过程的研究表明,配体中的酚羟基与四氮大环环中的质子之间存在较强的氢键.测得配体及配合物中酚羟基的pK_a分别为8.3和8.5.考察了上述3个配体的Zn(Ⅱ)配合物作为水解锌酶的模拟物催化对硝基苯酚乙酸酯(NA)水解的动力学行为,测得它们催化NA水解的二级反应速率常数k_c/［(mol/L^-1·s^-1］分别为3.48×10^-2、1.52×10^-2和2.85×10^-2.     

新型二硫杂环戊烯硫酮化合物的合成及其对谷氨酸诱导损伤HT22细胞的保护作用

在保留ADT-OH的3H-1,2-二硫杂环戊烯-3-硫酮结构的基础上,用芳乙烯基替换4-羟基苯环,设计并合成了6个二硫杂环戊烯硫酮化合物（L₁~L₆,其中L₂, L₃, L₅和L₆为新化合物）,其结构经¹H NMR, ¹³C NMR和HR-MS(ESI)表征。采用MTT法研究了L₁~L₆对谷氨酸诱导损伤的海马神经元HT22细胞的影响。药理初筛结果表明:给药浓度为10~100 μmol·L^-1时,L₁, L₂, L₄和L₆均能提高受损HT22细胞的存活率(P<0.01);给药浓度为1 μmol·L^-1时,L₃和L₅均可提高损伤HT22细胞的存活率(P<0.01)。     

吡啶二亚胺Ni(Ⅱ)配合物的合成、晶体结构及其催化乙烯聚合的研究

由三齿配体2,6-二[1-(2-甲基苯基亚胺)乙基]吡啶(L₁)和2,6-二[(1-苯基亚胺)乙基]吡啶(L₂)分别与NiCl₂.6H₂O在乙腈中反应,合成了两个吡啶二亚胺基氯化镍配合物L₁Ni(Ⅱ)Cl₂.CH₃CN(1)和L₂Ni(Ⅱ)Cl₂(2).通过元素分析、IR和¹HNMR对配体和配合物进行了结构表征,并测定了配合物1和2的晶体结构.X射线衍射分析结果表明,两个配合物均为五配位扭曲三角双锥构型,属单斜晶系,C_c空间群.配合物1的晶胞参数a=2.5783(5)nm,b=1.4843(3)nm,c=1.5866(3)nm;β=122.82(3),°V=5.1024(18)nm³,Z=4,R₁=0.0708,配合物2的晶胞参数a=1.5772(1)nm,b=0.8594(1)nm,c=1.5459(1)nm;β=103.27(1),°V=2.039(2)nm³,Z=4,R₁=0.0375.配合物1和2经MAO活化后对乙烯聚合表现出较低的催化活性.     

三嗪-吡唑钌配合物的合成、结构及光催化活性

光催化具有无污染、安全高效等优点,已成为环保领域的研究热点。 本文选择2,4-二(3,5-二甲基吡唑)-6-二乙基胺-1,3,5-三嗪(L₁)和2, 6-二[3-(5-甲基吡唑基)]吡啶(L₂)为配体、以RuCl₃为金属源,合成了3种配合物[Ru(L₁)Cl₃](1)、[Ru(L₂)₂]·Cl₃(2)和[Ru(L₂)₂]·(H₂BTC)·(HBTC)·H₂O(3),同时进行了IR、UV-Vis、TG及X射线衍射等表征,并对配合物在光催化降解罗丹明B方面进行了探讨,结果表明,配合物13均具有一定程度的光降解效果,降解效果分别为46.8%、44.7%和40.4%。 相同条件下,加入H₂O₂后的配合物13的降解效果比金属盐、配体及H₂O₂单独存在时的降解效果好。     

金纳米团簇在盐酸和十二硫醇刻蚀作用下的原位生长动力学研究

了解金属纳米团簇的形成机制对于进一步发展其化学制备方法是必要的。我们利用盐酸(HCl)和十二硫醇(RSH)共同刻蚀L₃ (L₃: 1, 3-双二苯基膦丙烷)包覆的多分散性的Au_n (15 ≤ n ≤ 60)团簇成功制备出单分散性的Au₁₃(L₃)₂(SR)₄Cl₄纳米团簇,并结合原位同步辐射X射线吸收谱、原位真空紫外-可见吸收光谱和质谱技术,研究了Au₁₃(L₃)₂(SR)₄Cl₄纳米团簇的动力学形成过程。结果表明,Au团簇从多分散到单分散的转变经历了3个明显不同的动力学步骤。首先,尺寸较大的多分散金属团簇Au_n主要在HCl刻蚀作用下,形成尺寸较小的亚稳的中间产物Au₈–Au₁₁团簇。然后,这些中间产物与反应溶液中已有的Au(Ⅰ)-Cl物种反应,并与SR发生部分配体交换,逐渐长大为由SR和L₃保护的Au₁₃团簇。最后,形成的Au₁₃团簇经过一个较缓慢的结构重组过程,最终形成稳定的Au₁₃(L₃)₂(SR)₄Cl₄的纳米团簇。     

γ-射线辐照法制备HDPE/PA6阻隔性材料及其性能研究

研究了富氧气氛中高密度聚乙烯(HDPE)的γ-射线辐照氧化及其与尼龙-6(PA6)的共混增容和共混材料的阻隔性能.FT-IR测试结果表明, 经γ-射线辐照的HDPE与PA6发生了化学反应或产生了弱相互作用.SEM照片显示4γHDPE (4h辐照,66Gy/min)与PA6具有良好的相容性,PA6在共混体系中呈层状分布.共混材料的阻隔性能测试结果表明4γHDPE/PA6共混物对二甲苯的阻隔性较HDPE/PA6共混物有明显提高.力学性能测试显示4γHDPE/PA6共混物力学性能优良.     

1,10-邻菲啰啉衍生物钌配合物的合成、 表征及与DNA和BSA的相互作用

通过2-(4-吡啶)-咪唑[4,5-f]-1,10-邻菲啰啉(L₁)与[Ru(η⁶-cymene)(μ-Cl)Cl]₂反应合成了3种新型芳基钌配合物, 并利用新配体2-(4-咪唑基苯基)咪唑[4,5-f]-1,10-邻菲啰啉(L₂)与RuCl₃反应合成了配合物4. 利用核磁共振波谱、 质谱等对配合物进行了表征. 通过紫外光谱和圆二色谱研究了配合物在缓冲溶液中的稳定性及与CT-DNA的相互作用, 利用荧光光谱研究了配合物与牛血清蛋白的作用, 用乌氏黏度计测试了配合物对DNA黏度的影响, 并通过荧光光谱、 凝胶电泳研究了配合物4在不同pH条件下的荧光响应及与pBR322 DNA的作用. 结果表明, 配合物通过嵌入的方式与DNA作用, 并对DNA的二级结构产生影响; 配合物1~4均可与牛血清蛋白的一个位点发生相互作用并使其发生静态荧光猝灭. 配合物4在光照条件下有活性氧生成, 可以使pBR322 DNA断裂并在酸性溶液中荧光增强.     

棕榈酸修饰的α-螺旋两亲性多肽的共组装

设计合成了3条棕榈酸修饰的两亲性多肽C₁₅H₃₁CO-(AEELAKK)₃-NH₂(PA1), C₁₅H₃₁CO-(AEALAKK)₃-NH₂(PA2) 和C₁₅H₃₁CO-(AEELAKA)₃-NH₂(PA3), 研究了其在水溶液中的自组装行为以及带净正电荷的PA2 和带净负电荷的PA3 等比例混合后的共组装行为, 并推测了其机理. 圆二色谱分析结果表明, 其二级结构均为α-螺旋结构, PA2和PA3等比例混合后α-螺旋含量升高. 利用透射电镜观察了PA1, PA2, PA3以及PA2+PA3(体积比1: 1)自组装体的形貌, 结果表明, PA2和PA3等比例混合后共组装形成了长的纳米纤维. 芘荧光探针研究了3种两亲性多肽以及PA2+PA3 的临界胶束浓度.     

Ag3PO4溶解热力学函数的晶面效应与温度效应

在室温下制备了立方体{100}、 四面体{111}、 菱形十二面体{110}和块体Ag₃PO₄微晶, 并进行了表征. 测定了其在不同温度下水溶液中的电导率, 结合强电解质溶液和溶解热力学理论, 得到了Ag₃PO₄微晶的溶解热力学函数. 以具有不同晶面的Ag₃PO₄微晶为模型, 研究了纳米材料溶解热力学函数的晶面效应和温度效应. 结果表明, 具有{110}晶面的菱形十二面体Ag₃PO₄的标准摩尔溶解吉布斯自由能()、 标准摩尔溶解焓()和标准摩尔溶解熵()最大, 具有{100}晶面的立方体Ag₃PO₄次之, 具有{111}晶面的四面体Ag₃PO₄最小; 溶解平衡常数(K_{\mathrm{SP}})和随着温度的升高而增大.     

聚甲醛和聚氨酯共混物的微观结构与力学性能

聚甲醛和聚氨酯共混物的微观结构与力学性能徐卫兵，朱士旺，蔡琼英（合肥工业大学化工学院合肥２３０００９）关键词聚甲醛，聚氨酯，共混物，微观结构，力学性能聚甲醛（ＰＯＭ）是６０年代发展起来的新型工程塑料，具有高密度、高结晶性，且坚硬、耐磨、自润滑、耐疲劳...     

酚醛树脂的增容作用对聚甲醛/丁腈橡胶共混物的韧性、结晶形态和亚微相态的影响

考察了酚醛树脂(Novolak)的增容作用对聚甲醛(POM)/丁腈橡胶(NBR)共混物的韧性、结晶形态和亚微相态的影响.实验结果表明,POM与NBR不相容,直接共混不能提高POM的韧性;添加Novolak后,当NBR质量分数为40%时共混物发生“脆-韧”转变.POM/NBR共混物中POM球晶尺寸大,易形成应力集中点,导致增韧效果不佳;Novolak可通过与POM的分子链间相互作用,改变POM分子链固有的规程和排列方式,使球晶显著减小.亚微相态显示,POM/NBR呈现“海-岛”结构相态,NBR在基体中分散性很差;添加Novolak可提高NBR在基体中的分散性;当NBR质量分数达到40%时,NBR在基体中呈现带状网络结构.网带结构能够终止受外力作用而在基体中产生的银纹和剪切屈服,增加了共混物的破裂能,从而使共混物的韧性显著提高.     

注塑温度对POM/TPU共混物分散相及力学性能的影响

研究了注塑温度对聚甲醛(POM)/热塑性聚氨酯弹性体(TPU)共混物形态结构和力学性能的影响.实验结果表明,注塑温度影响POM基体相与TPU分散相的粘度比,195℃时两者粘度相当,在剪切流动过程中,TPU可在POM基体中形成条状分散相,可吸收较多的冲击能并阻止银纹的生长以及裂纹的产生,从而较大幅度提高共混物的缺口冲击强度.     

Effect of ionomers on mechanical properties, morphology, and rheology of polyoxymethylene and its blends with methyl methacrylate-styrene-butadiene copolymer

Two ionomers, ethylene-methacrylic acid copolymer ionized with sodium cation (EMA-Na) and zinc cation (EMA-Zn), were employed as impact modifiers to prepare blends with polyoxymethylene (POM) via a melt extrusion. A copolymer of methyl methacrylate-styrene-butadiene (MBS) used as a co-impact modifier was also incorporated into the blends. The mechanical properties, thermal properties, morphology, and rheology were studied. A moderate toughening was observed for POM/ionomer binary blends, which was attributable to the rubbery natural and good adhesion of the ionomers. EMA-Zn exhibited a much better toughening effect than EMA-Na because of its higher elasticity and stronger interaction with POM. The incorporation of the ionomers into POM/MBS blends resulted in an improvement of mechanical properties, which was attributable to the compatibilizing effect of ionomer on POM/MBS blending system. The observation of scanning electron microscopy demonstrated that the finer phase domains were caused by incorporation of ionomers, which, acting as a compatibilizer as well as an impact modifier, reduced the interfacial tension and improved the interfacial adhesion between the phases. Differential scanning calorimetry investigation indicated that the presence of ionomer in the blends disturbed the crystallization of POM and resulted in a decrease in the crystallinity of POM. The evaluation of melt flow index revealed an increase in viscosity of the blends by incorporation of the ionomers, which was caused the ionic interaction between POM and the ionomers.     

聚甲醛与热塑性酚醛树脂相容性研究

考察了聚甲醛(POM)与热塑性酚醛树脂(Novolak)的相容性;浊点法研究结果表明,POM/Novolak共混物存在一个低位临界相转变温度.DSC测试表明,POM与Novolak共混后,共混物的熔点下降;通过DSC测试得到数据,采用Hoffman-Weeks平衡熔点外推法和Flory熔点下降方程推算出POM与Novolak的相互作用参数(χ)约为-0.032.FTIR研究表明,Novolak的羟基能够与POM的醚氧基形成氢键,导致共混物中Novolak的羟基峰向高频偏移.研究结果表明,POM与Novolak能够达到热力学相容.     

POM／EVA共混物的研究

用力学测试、扫描电镜（ＳＥＭ）、热分析（ＤＳＣ）等手段研究了聚甲醛（ＰＯＭ）与乙烯－醋酸乙烯酯共聚物（ＥＶＡ）共混物（ＰＯＭ／ＥＶＡ）的力学性能及其微同形态；用聚甲醛与马来酸二丁酯（ＤＢＭ）的接枝物（ＰＯＭ－ｇ－ＤＢＭ）作相溶剂，能改变共的两相间的粘结力，从而提出了共混物的力学性能，ＳＥＭ观察表明接枝物的加入改变了ＰＯＭ／ＥＶＡ共混物的断裂方式，微观形态及结晶性能，对其热性能影响不大；通过改变ＰＯ     

Carbon Monoxide Oxidation by Polyoxometalate‐Supported Gold Nanoparticulate Catalysts: Activity,Stability, and Temperature‐ Dependent Activation Properties

Nanoparticulate gold supported on a Keggin‐type polyoxometalate (POM), Cs₄[α‐SiW₁₂O₄₀]?n H₂O, was prepared by the sol immobilization method. The size of the gold nanoparticles (NPs) was approximately 2 nm, which was almost the same as the size of the gold colloid precursor. Deposition of gold NPs smaller than 2 nm onto POM (Au/POM) was essential for a high catalytic activity for CO oxidation. The temperature for 50 % CO conversion was ?67 °C. The catalyst showed extremely high stability for at least one month at 0 °C with full conversion. The catalytic activity and the reaction mechanism drastically changed at temperatures higher than 40 °C, showing a unique behavior called a U‐shaped curve. It was revealed by IR measurement that Au^δ+ was a CO adsorption site and that adsorbed water promoted CO oxidation for the Au/POM catalyst. This is the first report on CO oxidation utilizing Au/POMs catalysts, and there is a potential for expansion to various gas‐phase reactions.     

Carbon Monoxide Oxidation by Polyoxometalate‐Supported Gold Nanoparticulate Catalysts: Activity,Stability, and Temperature‐ Dependent Activation Properties

Nanoparticulate gold supported on a Keggin‐type polyoxometalate (POM), Cs₄[α‐SiW₁₂O₄₀]⋅n H₂O, was prepared by the sol immobilization method. The size of the gold nanoparticles (NPs) was approximately 2 nm, which was almost the same as the size of the gold colloid precursor. Deposition of gold NPs smaller than 2 nm onto POM (Au/POM) was essential for a high catalytic activity for CO oxidation. The temperature for 50 % CO conversion was −67 °C. The catalyst showed extremely high stability for at least one month at 0 °C with full conversion. The catalytic activity and the reaction mechanism drastically changed at temperatures higher than 40 °C, showing a unique behavior called a U‐shaped curve. It was revealed by IR measurement that Au^δ+ was a CO adsorption site and that adsorbed water promoted CO oxidation for the Au/POM catalyst. This is the first report on CO oxidation utilizing Au/POMs catalysts, and there is a potential for expansion to various gas‐phase reactions.     

Independence of the brittle–ductile transition from the rubber particle size for impact‐modified poly(vinyl chloride)

A series of acrylic impact modifiers (AIMs) with different particle sizes ranging from 55.2 to 927.0 nm were synthesized by seeded emulsion polymerization, and the effect of the particle size on the brittle–ductile transition of impact‐modified poly(vinyl chloride) (PVC) was investigated. For each AIM, a series of PVC/AIM blends with compositions of 6, 8, 10, 12, and 15 phr AIM in 100 phr PVC were prepared, and the Izod impact strengths of these blends were tested at 23 °C. For AIMs with particle sizes of 55.2, 59.8, 125.2, 243.2, and 341.1 nm, the blends fractured in the brittle mode when the concentration of AIM was lower than 10 phr, whereas the blends showed ductile fracture when the AIM concentration reached 10 phr. It was concluded that the brittle–ductile transition of the PVC/AIM blends was independent of the particle size in the range of 55.2–341.1 nm. When the particle size was greater than 341.1 nm, however, the brittle–ductile transition shifted to a higher AIM concentration with an increase in the particle size. Furthermore, the critical interparticle distance was found not to be the criterion of the brittle–ductile transition for the PVC/AIM blends. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 696–702, 2006     

Polyoxometalate-stabilized Pt nanoparticles and their electrocatalytic activities

The synthesis of long-term stable polyoxometalate (POM)-stabilized Pt nanoparticles (NPs) is described here. By means of controlled bulk electrolysis, the reduced POM anions, SiW(12)O(40)(4-) (or SiW(12)) and H(2)W(12)O(40)(6-) (or H(2)W(12)), respectively, served the dual role of reductant and protecting/stabilizing ligand for the Pt NPs. Transmission electron microscopy (TEM) images confirmed the formation of 3 to 4 nm sized Pt NPs, which coincidently was in the same size range of the commercial Pt black that was used as a reference. Elemental XPS analyses showed W/Pt ratios of 0.12 for the SiW(12)- and 0.18 for the H(2)W(12)-stabilized Pt NPs, but found no evidence of the presence of Cl(-) anion in the samples. Controlled electrochemical (EC), UV-Vis, and IR data provided unambiguous evidence for the structural integrity of the POM anions on the Pt NP surface. CO stripping, methanol oxidation reaction (MOR), and oxygen reduction reaction (ORR) were used to assess their electrocatalytic activities. It was found that both SiW(12)- and H(2)W(12)-stabilized Pt NPs showed enhanced activities in MOR and ORR as compared to that of Pt black, with the latter having higher enhancement. These observations clearly demonstrated that the stabilizing POM anions have a profound influence on the electrocatalytic activity of the underlying Pt NPs.