碳酸基替代的1,4,5,8-甲二胺在水溶液中的活性
Bindu Abraham1, Sun McMasters, Mellisa A Mullan
1Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, Maryland, USA.
Journal of the American Chemical Society
|April 1, 2004
概括
研究人员探索了水溶性纳二胺衍生物. 他们发现,碳酸盐替代化合物经历了分子内电子转移,形成潜在的激素生成的反应性物种.
科学领域:
- 摄影化学的使用.
- 有机化学 有机化学
- 超分子化学 超分子化学
背景情况:
- 1,4,5,8-纳二胺 (NDI) 衍生物是具有可调节的氧化还原和光物理性质的多功能有机分子.
- 了解激发状态动力学和反应性对于设计新的功能材料和光化学过程至关重要.
研究的目的:
- 为了合成和表征水溶性NDI衍生物与不同的替代剂.
- 通过激光闪光光学分析来研究这些NDI衍生物的兴奋状态反应性.
- 阐明电子转移和激素形成的机制.
主要方法:
- 合成水溶性1,4,5,8-纳二甲基二胺衍生物.
- 氧化还原和光物理性质的表征.
- 纳米秒激光闪光光电解研究与各种电子捐赠者和接受者.
- 热力学驱动力的计算.
主要成果:
- N,N'-bis[2-(N-pyridinium) ethyl]-1,4,5,8-naphthalene diimide (NDI-pyr) 显示了其三重激发状态的预期氧化火由电子捐赠者.
- 与α-和β-碳酸替代物的NDI衍生物表现出明显的反应性,激发状态与电子受体迅速反应.
- 在碳酸盐替代的NDI中形成的短暂物种被确定为从碳酸盐到NDI单片激发状态的分子内部电子转移的产物.
结论:
- NDI衍生物的光化学在很大程度上取决于替代物的性质.
- 碳酸盐替代NDI中的分子内电子转移为产生反应性物种提供了有效的途径.
- 这些发现为以碳为中心的激素的光化学生产开辟了新的途径.
相关概念视频
01:11Nucleophilic Aromatic Substitution: Elimination–Addition
Simple aryl halides do not react with nucleophiles. However, nucleophilic aromatic substitutions can be forced under certain conditions, such as high temperatures or strong bases. The mechanism of substitution under such conditions involves the highly unstable and reactive benzyne intermediate. Benzyne contains equivalent carbon centers at both ends of the triple bond, each of which is equally susceptible to nucleophilic attack. This 50–50 distribution of products is confirmed through isotopic...
01:13Relative Reactivity of Carboxylic Acid Derivatives
Carboxylic acid derivatives such as acid halides, anhydrides, esters, and amides undergo nucleophilic acyl substitution reactions with varying degrees of reactivity.
A key factor in assessing the reactivity of the acid derivatives is the basicity of the substituent or the leaving group. The lower the basicity of the leaving group, the higher the reactivity of the derivative. The basicity of the leaving group follows this order:
Halide ions < Acyloxy ions < Alkoxy ions < Amine ions
A key factor in assessing the reactivity of the acid derivatives is the basicity of the substituent or the leaving group. The lower the basicity of the leaving group, the higher the reactivity of the derivative. The basicity of the leaving group follows this order:
Halide ions < Acyloxy ions < Alkoxy ions < Amine ions
01:13meta-Directing Deactivators: –NO2, –CN, –CHO, –CO2R, –COR, –CO2H
All meta-directing substituents are deactivating groups. These substituents withdraw electrons from the aromatic ring, making the ring less reactive toward electrophilic substitution. For example, the nitration of nitrobenzene is 100,000 times slower than that of benzene because of the deactivating effect of the nitro group. The first step in an electrophilic aromatic substitution is the addition of an electrophile to form a resonance-stabilized carbocation. The energy diagrams for the...
01:14Nucleophilic Aromatic Substitution of Aryldiazonium Salts: Aromatic SN1
Treating arylamines with nitrous acid gives aryldiazonium salts that are effective substrates in nucleophilic aromatic substitution reactions. The diazonio group in these salts can be easily displaced by different nucleophiles, yielding a wide variety of substituted benzenes. The leaving group departs as nitrogen gas, and this easy elimination is the driving force for the substitution reaction.
In the Sandmeyer reaction, for example, the diazonio group is replaced by a chloro, bromo, or cyano...
In the Sandmeyer reaction, for example, the diazonio group is replaced by a chloro, bromo, or cyano...
01:20Diazonium Group Substitution with Halogens and Cyanide: Sandmeyer and Schiemann Reactions
Arenediazonium substitution reactions occur when the diazonium group is substituted by various functional groups such as halides, hydroxyl, nitrile, etc. For instance, arenediazonium salts react with copper(I) salts of chloride, bromide, or cyanide to form corresponding aryl chlorides, bromides, and nitriles. These reactions are named Sandmeyer reactions. Although the mechanism of this reaction is complicated, as illustrated in Figure 1, they are believed to progress via an aryl copper...
01:19Diazonium Group Substitution: –OH and –H
Nitrous acid, a weak acid, is prepared in situ via the reaction of sodium nitrite with a strong acid under cold conditions. This nitrous acid prepared in situ reacts with primary arylamines to form arenediazonium salts. Such reactions are known as diazotization reactions. As shown in Figure 1, the formation of arenediazonium salts begins with the decomposition of nitrous acid in an acidic solution to give nitrosonium ions.