吸电子基团

席夫碱芳环上的H被吸电子基团取代后，降低了Y分子筛超笼中封装的钴配合物的量，但能改善催化活性。

Substitution of the aromatic hydrogen atom of the Schiff base ligand with electron withdrawing group decreased the amount of the complex encapsulated in the zeolite cavities , but could improve the catalytic activity of the encapsulated complex .

在第二章中，我们通过在QA骨架的羰基位置引入吸电子基团NC-CH2-COOH设计并合成了两个系列新颖的有机染料。

In chapter 2 , we designed and synthesized two novel series of organic dyes by incorporating NC-CH2-COOH as electron withdrawing group at the carbonyl positions of QA skeleton .

给、吸电子基团对吡嗪衍生物电子结构影响的DFT研究

DFT study on Electronic structures of pyrazine derivatives with donor and acceptor group

而当R为吸电子基团-CHO、-COCH3时，主要发生分子内氮原子上的亲核取代反应，产物为含氮的五员杂环化合物。

In contrast , electro-withdrawing groups CHO and COCH_ 3 on the attacking site will favor the intramolecular nucleophilic substitution of nitrogen and form 5-membered heterocyclic compounds .

给/吸电子基团取代对PPV类电致发光聚合物光电特性的影响

Influence of Donor / Acceptor Substitutions on the Properties of Photo-electricity in PPV-like Electroluminescent Polymers

本文在B3LYP/6-31++G（d，p）水平，通过改变给电子基团或吸电子基团来研究分子内电荷局域激发（LE）和分子内电荷转移（CT）顺序的变化。

The sequence change of charge local excited ( LE ) and charge transfer ( CT ) is investigated by substituted electron donor or acceptor at the B3LYP / 6-31 + + G ( d , p ) level .

在超临界二氧化碳中对其它邻位有吸电子基团的端烯如丙烯醛、丙烯酸的Wacker反应也进行了研究。

In supercritical carbon dioxide , the Wacker oxidations of acrolein and of acrylic acid were also studied .

只有当底物带有强吸电子基团，反应无法进行。

Only when the substrates with strong electron-withdrawing group were failed in this reaction .

如果香豆素衍生物分子上含有吸电子基团，则还原电位正移；

The reductive potential of the derivatives will positively shift provided they contain electron acceptor .

分子内同时含有供电子和吸电子基团的化合物近年来成为人们竞相研究的热点。

The compounds with both electron-donor and electron-acceptor units have become a hot-spot in recently years .

于是我们成功的发展了亚胺和具有两个吸电子基团的环氧化合物的[3+2]环加成反应。

Then we developed the [ 3 + 2 ] cycloaddition of imines and oxiranes with two Electron-withdrawing groups .

分别讨论了它们催化合成苯环上带有-NO2、-CN、-CF3等吸电子基团的含氟芳香族化合物。

The synthesis of aromatic fluorides with substituted - NO2 , - CN , - CF3 are studied respectively .

吸电子基团使还原电位正移，推电子基团使还原电位负移。

Usually , the reduction potential is shifted to more positive by electron-attracting groups and to more negative by electron-repulsing groups .

方程说明5-位苯上引入体积小的吸电子基团可使抗惊活性提高。

Smaller steric volume and more powerful electron withdrawing effect of the substitution on the 5-phenyl ring increased the anticonvulsant activity .

相反，不能进行成环加成反应的反应物有吸电子基团的二烯和二烯烃取代物具有反式结构。

By contrast , the exo adduct possesses a trans relationship between the dienophile electron-withdrawing group and the trans diene substituent .

结果表明在丙烯酸酯的α-位存在供电子或吸电子基团对二聚反应的活性有不同的影响。

The results show that electron-donating or withdrawing groups at the α - site of acrylate can lead to different effect in the reactivity .

发现羰基酯上带有强吸电子基团时，反应不易控制。

It was observed that the reaction could not be controled easily for ketonic ester with strong electron-attracting group such as the nitro group .

吸电子基团能增强该类配合物对皮秒激光的限幅效果，而重原子效应则起相反的作用。

Electron withdrawing groups can enhance the limiting effect for this kind of complexes , but the effect of heavy atom acts opposite role .

聚2,7-咔唑材料的衍生物通过与吸电子基团共轭链接能够形成一类新型窄带隙光活性给体材料。

Poly ( 2,7-carbazole ) derivatives , incorporated by electron-withdrawing group in the main chain , form a new low band gap photoactive donor materials .

为进一步研究在氮的位置上引入吸电子基团的聚苯胺类衍生物的物理性质与化学结构之间的关系提供了依据。

It can be provided with some information on studying of the relationship between physical properties and chemical structure by introduction of the electron-withdrawing groups to the nitrogen of aniline .

三种染料与其母核染料的光降解对比试验说明，甲川链上引入吸电子基团使得染料光稳定性提高，而供电子基团则光稳定性下降。

The photodegradation experiment showed that the introduction of electron withdrawing group on methane chain would improve the photo-stability of the dye , while electron donating group would decrease the photo-stability .

并且对亲核试剂的体积效应、溶剂效应对亲核性影响，底物上吸电子基团的数目、吸电子能力对亲电性的影响，以及亲核取代反应的发生部位受哪些因素影响进行探讨。

At the same time , discuss about the impact factor to nucleophilicity such as the number of attract electron group 、 ability of attract electron and the nucleophilic substitution reaction part .

该研究结果表明，侧链不同吸电子基团可以导致其相应聚合物的能隙发生变化，从而使其具有不同的颜色显示。

All the results show that the band gap of the polymer can be tuned by the acceptor group of the side-chain , which leads to the different colors showing under different applied potentials .

在碱金属亚硝酸盐和碳酸盐存在下，被强吸电子基团取代的硝基苯在非质子极性溶剂中能发生自身缩合反应，生成结构对称的双取代二苯醚，收率较高。

In the present of alkali nitrite and carbonate , some nitrobenzenes substituted by strongly electron withdrawing groups undergo a self condensation in an aprotic polar solvent to give symmetrical disubstituted diphenyl ethers in good yields .

结果表明分子的前线轨道与分子的激发态结构关系密切，酯键取代导致电荷向吸电子基团移动，化合物的有效共轭长度缩短，偶极矩差变小，能隙变大，光谱明显蓝移。

Ester as substituent leads the negative charge transfer to electron-Withdrawing group , the effective conjugation length and dipole moment difference becomes small . Energy gap is enlarged , and thus the absorption spectral nature exhibits blue-shift significantly .

与此同时，国内外的大量文献已报道含有吸电子基团的第二类和第三类金属卟啉比第一类金属卟啉有更强的催化性能。

At the same time , a lot of literatures at home and abroad have reported that the second and third generations of metalloporphyrins with electron-withdrawing substituents shows higher catalytic activity for the oxidation of alkane than the first .

通过苯乙烯与二乙烯苯聚合、共聚物纯化、引入吸电子基团、磺化、活性基因稳定化过程，合成耐温强酸阳离子交换树脂催化剂。

The macroporous , strongly acidic , high thermally stable canon exchange resin catalysts were synthesized in the steps of polymerization of styrene and divinylbenzene , purifying copolymer , introducing electron withdrawing group , sulfonation and stabilizing active sites .

当3位上有H原子或供电子基团时，羰基化可在2位上进行，但3位上的吸电子取代基团会抑制羰基化。

When an H atom or electron donating group ( i.e. , CH 3 ) was present at the 3 position , hydroxylation proceeded at the 2 position , but the presence of electron withdrawing substituent groups ( i.e. , OH or COOH ) at the 3 position inhibited hydroxylation .

香豆素类化合物具有较好的荧光性能，荧光强度与7位供电基向香豆素环内的内酯键中的羰基发生分子内电荷转移有关，各种荧光性能可通过香豆素母体上吸供电子基团的修饰来实现。

Coumarin compounds have good fluorescence performance , fluorescence intensity has some to do with C-7 electron-donating group transferring charge intra-molecularly to carbonyl in coumarin ring lactone , all kinds of fluorescence performance can be achieved by modifying electronic groups in coumarin structure .

结果表明，具有高度离域的共轭体系及强的吸电子和供电子基团导致分子具有大的第一超极化率。

Results indicate that molecule units containing highly delocalized conjugated system and strong electron acceptor and electron donor lead to molecules'large molecular first hyperpolarizabilities .