首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 265 毫秒
1.
桑大永  田娟  计国桢 《中国化学》2006,24(9):1109-1116
基于芘的荧光发射单体峰的相对强度对环境极性的敏感这一性质,设计并合成了芘标记的长链荧光探针。采用稳态荧光发射光谱和激发光谱以及紫外吸收光谱研究了该探针的簇集行为。发现其极性在临界簇集浓度附近发生突变,可以用来表征簇集。随后用它作为极性探针,研究了三个长链烷烃,三个胆固醇酯和三个含支甲基的化合物的结构与它们形成的簇集体的极性的关系,并用链长效应和支甲基效应对这些关系做了讨论。根据这些结果对簇集体的结构性质做了推测。  相似文献   

2.
通过还原、溴代、氰化、Wittig反应等七步反应设计合成了一新二元电子给体-受体(D-A)化合物:4-[2-(9,10-二氰蒽)乙烯基]-N-甲基-N-十六烷基苯胺(DCACMA,反式)并初步研究了其吸收光谱行为。研究表明,基态下DCACMA分子中电子给体与电子受体(CMA与DCA)间存在显著的电荷转移相互作用,在LB膜及簇集态(DMSO-H2O二元体系中)下,DCACMA分子呈H-型簇集排列。  相似文献   

3.
本文以对-三氰基乙烯基-N,N-二烷基苯胺为模型化合物,开展共轭π电子体系分子内光致电子转移及电荷分离的研究。通过吸收光谱和荧光光谱探讨了这类分子的电荷分离作用以及在DMSO-H_2O中的簇集作用。  相似文献   

4.
通过3-乙氧甲酰基-4-羟基-2-氢(甲基)-2H-1,2-苯并噻嗪-1,1-二氧化物与取代嘧啶胺或均三嗪胺的胺解反应,合成了标题化合物。生物活性测定结果表明多数化合物具有较好的除草活性,部分化合物显示好的植物生长调节活性和抗炎免疫活性。  相似文献   

5.
通过3-乙氧甲酰基-4-羟基-2-氢(甲基)-2H-1,2-苯并噻嗪-1,1-二氧化物与取代嘧啶胺或均三嗪胺的胺解反应,合成了标题化合物。生物活性测定结果表明多数化合物具有较好的除草活性,部分化合物显示好的植物生长调节活性和抗炎免疫活性。  相似文献   

6.
以膦酰甲酸(PFA)为先导化合物,将氨基酸酯引入PFA中,使其N-端与磷原子相连,利用膦酰氯与氨基酸酯盐酸盐在碱存在下反应,合成了化合物(Ⅰ),(Ⅰ)胺解得化合物(Ⅱ)。以l-氨基酸为原料反应,对其产物的异构体进行了分离和测定;通过用光学活性的(Ⅰ)进行胺解和分离非消旋体胺解混合物两种途径,均得到了单一构型的(Ⅱ),并经(Ⅱ)的单晶X-线衍射,证实了化合物的绝对构型。  相似文献   

7.
三级胺及酰胺硝解研究进展   总被引:1,自引:0,他引:1  
综述了三级叔胺及酰胺硝解的近期研究进展,重点是已作为或有可能成为高能量密度化合物硝胺的合成。讨论了三级胺及酰胺的硝解历程,汇集了常用的硝化及硝解系统。详细阐述了烷基叔胺、叔酰胺、烷基酰基叔胺。特别是多环笼形叔胺和叔酰胺的硝解反应及硝解条件。  相似文献   

8.
合成了一系列含有1,5-二氧萘基仿生体系的线性供体和折叠体, 用稳态荧光光谱法定量研究了它们的临界簇集浓度(CAgC)及其影响因素. 结果显示, DX(1,4-二氧六环, Dioxane)-H2O和CH3CN-H2O二元溶剂中的簇集程度与Ф值(有机溶剂的体积分数)有关. 在DX-H2O和CH3CN-H2O体系中, 分子间与分子内π-π芳环堆积作用能促进簇集. 折叠体的分子内折叠加强了簇集程度. 线性供体的自卷曲程度随Ф值的增大而变小, 随分子中1,5-二氧萘基数目的增多而增大.  相似文献   

9.
蒋锡夔  计国桢 《化学通报》2003,66(3):147-161
有机分子簇集和自卷是研究疏水亲脂作用(HLI)最基本和最简单的模型,它直接影响受体分子的反应性和生物功能,用物理有机化学的概念和方法研究簇集和自卷是了解HLI最好的途径之一。自由基化学研究中,取代三氟苯乙烯是迄今为止唯一可真正拆分取代基极性效应和自旋离域效应的体系。σJJ是最可靠和种类最多的反映取代基自旋离域能力的参数,首次提出一般情况下,可用双参数方程系数|ρ^+/ρJJ|比值作为取代基极性效应和自旋离域效应相对权重的判别尺度,将自由基反应及波谱参数的相关分析分为四种类型,成功解决了长期困扰自由基化学界如何评估这两种效应的重大问题。  相似文献   

10.
卤代化合物的光化学反应研究进展   总被引:1,自引:0,他引:1  
介绍近年来卤代化合物在光照射下的偶联反应、醇解反应、消去反应、开环反 应,尤其是卤代杂环化合物的光化学反应,得到了许多用热反应或催化反应无法替 代的具有生物(理)活性的中间体.  相似文献   

11.
A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.  相似文献   

12.
The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp3)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp2)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp2)?H and aliphatic 1,5- and 1,6-C(sp3)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp3)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp2)?H insertion.  相似文献   

13.
N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).  相似文献   

14.
An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y1 and Y2. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.  相似文献   

15.
In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.  相似文献   

16.
An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.  相似文献   

17.
Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.  相似文献   

18.
用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.  相似文献   

19.
An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6ag and imidazo[1,5-a]quinoxalines 7ah by the reaction of 2-imidazolyl anilines 4ac with aryl aldehydes 5ak under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4ab was found to be instrumental for the success of the reaction.  相似文献   

20.
The Diels-Alder reactivity of 1,2-heteroborines (H4C4B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号