共查询到19条相似文献,搜索用时 72 毫秒
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建立了MmL1S型三元复合物催化反应通用的数学模型 ,获得了催化反应有关的热力学和动力学参数 ,考察了 30℃ ,pH 7 0 0、N 甲基二乙醇胺Ni2 + ,Zn2 + ,Co2 + 配合物对α 吡啶甲酸对硝基苯酚酯 (PNPP)水解反应的催化作用 ,以及非离子表面活性剂Brij 35对催化水解反应的影响 ,结果表明 ,配体中活化的羟基作为亲核物种对羧酸酯有较强的亲核反应能力 ,能有效地促进PNPP的水解 ,金属离子活性的大小顺序为Ni2 + >Zn2 + >Co2 + 。 相似文献
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带有苯酚侧臂的四氮大环Zn(Ⅱ)配合物催化羟酸酯水解研究 总被引:3,自引:0,他引:3
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配合羟基的PKdisplay status 相似文献
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大环钴(Ⅱ)配合物模拟水解酶催化羧酸酯水解的比较研究 总被引:4,自引:0,他引:4
在Brij35胶束溶液中,比较研究了四氮大环席夫碱(5,7,7,12,14,14-六甲基-1,4,8,11-四氮杂十四环-二烯,L)的钴(Ⅱ)配合物1催化对硝基苯酚吡啶甲酸酯(PNPP)及对硝基苯酚乙酸酯(PNPA)水解的动力学。结果表明:配合物1对PNPP及PNPA的催化作用具有酸碱催化的特征,催化活性物种为与金属离子结合的氢氧根离子CoL-OH-;配合物1催化PNPP水解的速度远远大于其催化PNPA水解的速度,在pH 7.40、30℃时,表观二级速率常数kc分别为0.997mol-1·L·s-1和1.12×10-3mol-1·L·s-1,这种反应速率的差异可归因于反应机理的不同;Brij35胶束对PNPP及PNPA的水解均有抑制作用。 相似文献
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合成了链酚胺型 N3O配体 N-(2-羟基苄基 )-二乙烯三胺 (HL),用元素分析 ,IR和 1H NMR等手段进行了表征。用 pH电位滴定法,在 25± 0.1℃ ,I=0.10(KNO3)条件下,研究了该配体质子化及其与 Zn?离子配位热力学。在 25± 0.1℃ ,I =0.10(KNO3), pH =7~ 9(50mmol· L- 1缓冲溶液 )范围内,通过分光光度法测定了配合物催化对硝基苯酚乙酸酯 (NA)水解动力学,得到了 NA催化水解二级反应速率常数 kc。结果表明: Zn?离子与配体的氨基和酚羟基配位之后,还与一个水分子配位。配位酚羟基和水分子的离解常数 pKa值分别为 5.22和 9.47。在中性 pH值可以产生亲核试剂 Zn?…- OH,对 NA水解有较好的催化效果, pH=9.0时, kc=3.2× 10- 2mol- 1· L- 1· s- 1。 相似文献
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多羟乙基双核大环多胺La(Ⅲ)配合物对双对硝基苯酚磷酸二酯和DNA催化水解作用研究 总被引:1,自引:1,他引:1
合成了一类新型多羟乙基双核大环多胺La(Ⅲ)配合物,其结构经1H NMR,MS,元素分析等表征.通过紫外分光光谱法和琼脂糖凝胶电泳技术,研究了双核大环多胺La(Ⅲ)配合物催化双对硝基苯酚磷酸二酯的水解反应和对质粒DNA(pUC18)的催化水解作用.结果表明:双核大环多胺La(Ⅲ)配合物可以有效催化双对硝基苯酚磷酸二酯水解和促进质粒DNA在生理条件下的水解裂解.双对硝基苯酚磷酸二酯的水解速率提高了2.36×104倍.讨论了配合物结构对水解反应的影响. 相似文献
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Kou Xingming Meng Xiangguang Xie Jiaqing Zeng Xiancheng 《Transition Metal Chemistry》2003,28(7):777-781
The comparative kinetic investigation of the hydrolysis of p-nitrophenyl picolinate (PNPP) and p-nitrophenyl acetate (PNPA) catalyzed by the tetracoordinate macrocyclic Schiff base complex of zinc(II) (1) at 30 °C is reported. The results indicate that the (1) catalyzed hydrolyses of PNPP and PNPA are acid-base catalytic processes and that the active species is the metal bound hydroxide ion, namely, ZnL—OH–. (1) promoted hydrolysis of PNPP proceeds much faster than that of PNPA. At pH 7.51, the apparent second-order rate constants k
c for hydrolysis of PNPP and PNPA are 0.254 and 7.28 × 10–3 mol–1 dm3 s–1, respectively. The difference in hydrolytic rates may be attributed to the difference of hydrolytic mechanisms by which the PNPP and PNPA operate. The reasons are discussed in detail. 相似文献
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研究羧酸酯和磷酸酯的水解在环境和生物应用等方面具有越来越重要的意义。为实现对环境友好、高经济效益的生产过程,许多研究者致力于研发反应条件温和、催化效率高和高度专一性的催化剂。因而,仿酶研究倍受人们的关注,其中,水解金属酶是被研究得较为广泛的一类。我们曾报道过异羟肟酸过渡金属配合物仿生催化氧化性能和二氧亲合性能。本文我们将4种聚醚桥连二异羟肟酸过渡金属铜(Ⅱ)、锌(Ⅱ)、钴(Ⅱ)和锰(Ⅱ)配合物(见图1)作为仿水解酶模型,在底物浓度高于催化剂浓度10倍以上的条件下,研究了配合物在缓冲溶液中催化α-吡啶甲酸对硝基苯酯(PNPP)的水解反应的机理,并建立了相应的动力学数学模型;考查了配合物中心金属离子、溶液酸度和反应温度等对催化PNPP水解反应性能的影响。 相似文献
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Salassa G Castilla AM Kleij AW 《Dalton transactions (Cambridge, England : 2003)》2011,40(19):5236-5243
A metal template approach affords in high yield a tetra-Zn(salphen) macrocycle (3) which shows strong and cooperative self-assembly mediated by the formation of Zn(salphen) dimer units held together via μ(2)-phenoxo interactions. A cooperative binding mode for the tetranuclear Zn(4) macrocycle 3 is supported by comparison of UV-vis and fluorescence titration data recorded for 3 when compared with respective mononuclear and dinuclear Zn(salphen) model compounds. UV-vis dilution experiments carried out for Zn(4) macrocycle 3 and its Pd(4) analogue 4, as well as comparative TEM studies involving the same tetranuclear macrocycles further support the strong assembly behavior of 3. This self-assembly seems to be primarily dictated by its ability to form multiple, self-assembled dimeric [Zn(salphen)](2) units. 相似文献
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Two Schiff base Co(II) complexes were synthesized and used to catalyze the hydrolysis of p-nitrophenyl picolinate (PNPP) in Gemini 16-2-16 micellar solution. For comparison, hydrolytic kinetics of PNPP was respectively
investigated in the micellar solutions of three kinds of conventional single-chain cationic, anionic, and nonionic surfactants,
i.e., hexadecyltrimethylammonium bromide (CTAB), n-lauroylsarcosine sodium (LSS), and polyoxyethylene(23) lauryl ether (Brij35). Experimental results showed that the one complex
with small Schiff base ligands exhibited better catalytic activity than the other one with bigger ligands towards the PNPP
hydrolysis under comparable conditions, which testified that a relatively open catalytic site is essential for tuning the
activities of the two mimic hydrolases. Moreover, compared effects of various micellar solutions demonstrated that Gemini
16-2-16 micellar solution is the best reaction medium relative to its single-chain analogs. 相似文献
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Neodymium-based heterocyclic Schiff base complex was prepared and applied for the coordination polymerization of isoprene. This complex polymerized isoprene to afford products featuring high cis-1,4 stereospecificity (ca. 95%) and high molecular weight (ca, 10^5) in the presence of the triisobutyl aluminium (AliBu3) as cocatalyst, The microstructure of obtained polyisoprene was investigated by FTIR, 1^H NMR. Two different kinds of active centers in the catalyst system were examined by GPC method. 相似文献
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25 0±0 01℃时,研究了带有咪唑基团的配体与二价过渡金属离子生成的配合物在三种不同的表面活性剂(CTAB,Brij35和LSS)中催化对硝基苯酚吡啶甲酸酯(PNPP)水解的动力学。运用金属胶束催化的三元复合物动力学模型对所得的实验结果进行定量处理,得到了相关的动力学和热力学参数。结果表明:pH7 00时,在任何一种配合物与不同的表面活性剂生成的金属胶束溶液中,PNPP的水解速率都有较大的增加,尤其是铜(Ⅱ)配合物与两性离子表面活性剂(LSS)以及非离子表面活性剂生成的金属胶束对PNPP的水解反应表现出较高的催化活性,而在阳离子表面活性剂中,配合物催化PNPP水解反应的效率却并不高,这可能归因于阳离子表面活性剂带正电的极性头与金属离子之间的静电相斥作用;在所研究的三种配合物中,尽管Cu(Ⅱ)配合物具有最低的pKa值,但是在弱碱性条件下,Zn(Ⅱ)配合物却表现出更高的催化活性,这可能与催化剂在胶束溶液中的离子化状态以及不同配合物中活性物种的不同亲核能力有关。 相似文献
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A new methodological approach for the determination of Ag+ by the perturbations caused by different amounts of Ag+ on a novel Belousov-Zhabotinskii oscillating system is proposed. Such a novel oscillating system involves the participation
of an unsaturated macrocyclic Cu(II) complex, [CuL](ClO4)2, as catalyst and malic acid as substrate. The ligand L in the complex is 5,7,7,12,14,14-hexemethyl-1,4,8,11-tetraazacy-clotetradeca-4,11-diene.
The linear relationship between the change in the oscillating period of the chemical system and the logarithm of [Ag+] is found in the range 6.25 × 10−5 to 1.00 × 10−7 M. The obtained RSD is 0.8%. The probable mechanism involving the perturbation of Ag+ is also discussed.
The text was submitted by the authors in English. 相似文献