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1.
采用活化能和基于密度泛函理论B3LYP/6-31G(d)水平的计算方法研究了5-硝基-2-呋喃甲醛-N-甲腙和7-氧杂双环[2,2,1]-2,5-二烯基-2,3-庚二酸甲酯的1,3-偶极环加成反应的机理以及区域选择性,计算结果与实验值一致. 该反应通过异步协同机制进行.  相似文献   

2.
用密度泛函理论研究了单重态二甲基亚硅基卡宾与丙酮环加成反应的反应机理,势能面结果表明该反应有两条相互竞争的主反应通道. 反应规律为:二甲基亚硅基卡宾中的π轨道与π键化合物中π轨道的[2+2]环加成作用造成了扭曲四员环中间体和平面四员环产物的形成;平面四员环产物中卡宾C原子的不饱和性,导致了甲基迁移产物和硅杂双环化合物的生成.  相似文献   

3.
制备了Eu (Ⅲ)配合物纳米颗粒并对其进行表面修饰以用于Cu(I)离子的检测。所采用的探测机制是源于Cu(I)离子催化的末端炔基和叠氮基团之间的1,3极性环加成。通过该反应,在Eu3+配合物纳米颗粒(给体)和一种荧光染料分子(受体)之间建立了共振能量传递关系。因为点击反应的速度正比于Cu(I)离子的浓度,因此通过监测染料分子荧光强度的变化即可检测出Cu(I)离子的浓度。基于共振能量传递机制和点击反应的敏感性,浓度为微摩尔量级的Cu(I)离子可以被探测到。  相似文献   

4.
制备了Eu(Ⅲ)配合物纳米颗粒并对其进行表面修饰以用于Cu(I)离子的检测。所采用的探测机制是源于Cu(I)离子催化的末端炔基和叠氮基团之间的1,3极性环加成。通过该反应,在Eu3+配合物纳米颗粒(给体)和一种荧光染料分子(受体)之间建立了共振能量传递关系。因为点击反应的速度正比于Cu(I)离子的浓度,因此通过监测染料分子荧光强度的变化即可检测出Cu(I)离子的浓度。基于共振能量传递机制和点击反应的敏感性,浓度为微摩尔量级的Cu(I)离子可以被探测到。  相似文献   

5.
DTE-甲亚胺叶立德盐(DTE:二噻吩乙烯基)与C60在甲苯中的1,3-偶极环加成反应被用于合成新型的哑铃型富勒烯化合物1.为了与1作比较,还同时合成了单加成物2.并通过HF-3/21G方法计算确定了这两种化合物分子的几何结构,同时在室温下测定了化合物在不同极性溶剂中的紫外-可见光谱和荧光光谱,证明了化合物内给体和受体间光诱导分子内电子转移过程的存在.  相似文献   

6.
糠酸甲酯是随着2,5-呋喃二甲酸二甲酯新合成方法的发展而发展起来的一种新型可再生生物燃料. 本文用CCSD(T)/CBS//M062X/cc-pVTZ方法研究了糠酸甲酯与羟基自由基之间的势能面,包括夺氢反应和加成反应. 确定了异构化和分解反应生成的初级自由基. 结果表明,支链甲基上的夺氢反应是主要的反应通道,呋喃环上的OH加成具有明显的压力依赖性. 本文提出的速率系数为糠酸甲酯燃烧机理的改进提供了重要的动力学数据,为进一步研究实际燃料的燃烧过程奠定了良好的基础.  相似文献   

7.
分子模拟在生物化学中的应用实例   总被引:2,自引:0,他引:2  
分子模拟是一种描述和模拟分子和分子体系运动状态和性质的方法.随着电子计算机技术的飞速发展,分子模拟进入了一个前所未有的新时代.在此之前,人们只能通过机械模型和纸笔计算进行简单的分子模拟,现在通过利用电子计算机人们可以做更为复杂、更为全面的分子模拟.本文通过两个实例来简单阐述了分子模拟在生物化学中的应用.一则是通过模拟膦酰基氧化腈和丙乙腈的1,3偶极环加成反应过程,用密度泛函理论方法在B3LYP/6-31G(d,p)水平上解释了得到2∶1的加成产物的现象,来解释1,3偶极环加成反应得到2:1加成产物的现象.一则是通过结构生物信息学的方法建立H5N1高致病性禽流感病毒蛋白的三维结构,模拟其与一些药物分子的相互作用,研究H5N1的活性中心.  相似文献   

8.
刘海波  许明  袁铃 《波谱学杂志》2013,30(4):594-601
通过Cu(I)催化有机叠氮化物和端基炔之间的1,3-偶极Huisgen环加成反应,又称“点击化学”, 可快速、高效合成专一的1,4-二取代-1,2,3-三唑产物. 为得到含有末端炔的喹啉酮衍生物,以7,8-二氢-2,5(1H,6H)-二酮(1)为原料,通过烷基化反应将端基炔引入到化合物1中,合成了1-(2-炔丙基)-7,8-二氢喹啉-2,5(1H, 6H) 二酮(3),并利用重结晶和硅胶柱分离两种化学手段,得到了该化合物的两种构型异构体. 采用DEPT、1H NMR、13C NMR、1H-1H COSY、NOESY、HMQC多种NMR实验测试分析方法,对该化合物的构型异构体进行了验证和区分,并分别对其1H NMR和13C NMR谱的信号进行了归属.  相似文献   

9.
环加成反应是在光或热的条件下,两个或多个不饱和分子通过双键相互加成生成环状化合物的反应。本研究以1,4-二[2-(4-吡啶)乙烯基]苯(BPEB)为前驱体,通过二甲基亚砜(DMSO)液相光诱导反应获得了BPEP二聚体。与在晶体固相中制备方法相比,该方法不需要模版剂或培养特定结构的晶体、能耗少、操作简单。同其他液相中2+2环加成反应相比,该方法不需要使用催化剂。该研究通过核磁以及红外光谱对环加成产物进行表征,此方法获得的目标产物特异性好及产率高等特点。  相似文献   

10.
以呋咱环为基本结构单元可以构建多系列性能优异的新型呋咱含能衍生物,它们一般具有能量密度高,标准生成焓大,氮含量高以及分子热力学稳定性较好等优点。3-叠氮-4-氨基呋咱(AAF)作为合成三唑联呋咱、多叠氮基呋咱、呋咱醚、腈基呋咱等多类含能化合物的重要中间体,而且本身也是一个高能量密度化合物,因此探讨其合成方法具有一定的意义。3-叠氮-4-氨基呋咱的合成路线如图1所示,合成分为3步:第一步是乙二醛与盐酸羟胺在氢氧化钠溶液中发生加成缩合反应得N-氨基乙二肟(DAG)。该反应具有强放热性,实验操作应小心。  相似文献   

11.
The inhibition effect of Schiff bases benzylidene-(2-methoxy-phenyl)-amine (A), (2-methoxy-phenyl)-(4-methyl-benzylidene)-amine (B), (4-chloro-benzylidene)-(2-methoxy-phenyl)-amine (C) and (4-nitro-bezylidene)-(2-methoxy-phenyl)-amine (D) on the corrosion of aluminum in 1 M HCl has been studied by polarization, electrochemical impedance spectroscopy (EIS) and weight loss measurements. It has been found that all the studied Schiff bases are excellent inhibitors. Maximum inhibition was obtained for 0.01 M Schiff base A. Results show that the inhibition efficiency increases with decreasing in temperature and increasing in concentration of Schiff base. Polarization curves reveal that the used inhibitors are mixed type inhibitors. The surface adsorption of the Schiff bases leads to a decrease of double layer capacitance as well as an increase of polarization resistance. The inhibitor performance depends strongly on the type of function groups substituted on benzene ring. The adsorption of used compounds on the aluminum surface obeys a Langmuir isotherm and has a physical mechanism. Thermodynamic parameters for both dissolution and adsorption processes were determined. The quantum chemical study of the corrosion inhibition efficiency of the Schiff bases on Al in molar HCl was carried out.  相似文献   

12.
郭雅慧  孙元红  陶丽敏  赵珂  王传奎 《中国物理》2005,14(11):2202-2207
Time-dependent hybrid density functional theory in combination with polarized continuum model is applied to study the solvent effects on the geometrical and electronic structures as well as one- and two-photon absorption processes, of a newly synthesized asymmetrical charge-transfer organic molecule bis-(4-bromo-phenyl)-[4-(2-pyridin-4-yl-vinyl)phenyl]-amine (BPYPA). There exist two charge-transfer states for the compound in visible region. The two-photon absorption cross section calculated by a three-state model and solvatochromic shift of the charge-transfer states are found to be solvent-dependent, where a nonmonotonic behaviour with respect to the polarity of the solvents is observed. The numerical results show that the organic molecule exhibits a rather large two-photon absorption cross section as compared with the compound 4-trans-[p-(N, N-Di-n-butylamino)-p-stilbenyl vinyl] pyridine (DBASVP) reported previously, and is predicted to be a good two-photon polymerization initiator. The hydrogen-bond effect is analysed. The computational results are in good agreement with the measurements.  相似文献   

13.
The second‐order rate constants k (dm3 mol?1 s?1) for the alkaline hydrolysis of phenyl esters of meta‐, para‐ and ortho‐substituted benzoic acids in aqueous 5.3 M NaClO4 and 1.0 M Bu4NBr were measured by UV/Vis spectrophotometry at 25 °C. The variations in the ortho inductive, ortho resonance, as well as meta and para polar effects with solvent parameters were studied using data for the alkaline hydrolysis of phenyl esters of substituted benzoic acids in various media. The dependence of the ortho substituent effect on solvent can be precisely described with the following equation: Δlog kortho = log kortho ? log kH = 0.059 + 2.19σI + 0.304σ°R + 2.79E ? 0.016ΔI ? 0.085Δ°R, where ΔE is the solvent electrophilicity, ΔE = ES ? EH2O, characterizing the hydrogen‐bond donating power of the solvent. The increase in the meta and para polar substituent effects with decrease in the solvent hydrogen‐bond donor capacity (electrophilicity) was approximately to the same extent (?0.068Δ°m,p) as the resonance term for the ortho substituents. The steric term of ortho substituents was independent of the solvent parameters. The variations in the ortho inductive, ortho resonance, as well as meta and para polar substituent effects with the solvent electrophilicity were to the same extent as in phenyl benzoates containing the substituents in the phenyl part. The substituent effects in the alkaline hydrolysis of ethyl benzoates appeared to vary with the solvent electrophilicity nearly to the same extent as in the alkaline hydrolysis of substituted phenyl esters of benzoic acids. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

14.
光谱法研究3H-吲哚季铵盐探针分子与牛血清底的相互作用   总被引:3,自引:0,他引:3  
合成了一种新型的荧光探针分子2-(对-十二烷基氨基)苯基-3, 3-二甲基-5-乙酯基-3H-吲哚基-甲基-二-十六烷基碘化铵, 并运用荧光光谱探讨它与牛血清蛋白的作用. 结果表明, 探针分子与牛血清蛋白(BSA)的结合作用可使3H-吲哚的荧光强度增强, 而对蛋白质却具有猝灭性质, 其结合常数和结合位点数分别为Ka=1.995×105 dm3*mol-1和n=1.12.  相似文献   

15.
The optical properties of several azobenzene derivatives were modulated by varying the dipole moments and conjugation lengths of the D‐π‐A systems. The relationship between the structure and absorption spectrum and polarizability was studied in the gas phase, THF and MeOH solutions, respectively, by using the density functional theory. The calculated absorption spectra and second‐order polarizabilities are in good agreement with the available experimental observations. In comparison with the D‐π‐A monomer, the H‐shaped D‐π‐A dimer almost doubles the dipole moments and hence increases the second‐order polarizabilities, without a significant shift in the maximum absorption bands. The addition of another azobenzol group between electron‐donating and ‐accepting groups increases the second‐order polarizabilities by 4–6 times, but leads to an evident red‐shift of about 65–80 nm in spectra. The relative second‐order polarizability of the halogen‐substituted derivatives is in the sequence of ? CF3 > ? F > ? Cl > ? Br, without obvious substituent effects on the optical transparency. The D‐π‐A chromophores with the strong electron‐donating (amino) and ‐accepting (acetyl) substituent present the larger second‐order polarizabilities, at the cost of about 20 nm red‐shift of the maximum absorption lengths relative to the halogen‐substituted species. It is also demonstrated that both the linear and nonlinear optical properties augment with the increase in solvent polarity, accompanied by a red‐shift in the wavelengths of maximum absorption by about 18 and 23 nm, respectively, in THF and MeOH solutions. The changes in optical properties upon the structural modifications are further rationalized by the electronic structures of various H‐shaped dimers. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

16.
The second‐order rate constants k (dm3mol?1s?1) for alkaline hydrolysis of meta‐, para‐ and ortho‐substituted phenyl esters of benzoic acid, C6H5CO2C6H4‐X, in aqueous 50.9% (v/v) acetonitrile have been measured spectrophotometrically at 25 °C. In substituted phenyl benzoates, C6H5CO2C6H4‐X, the substituent effects log kX ? log kH in aqueous 50.9% acetonitrile at 25 °C for para, meta and ortho derivatives showed good correlations with the Taft and Charton equations, respectively. Using the log k values for various media at 25 °C, the variation of the ortho substituent effect with solvent was found to be precisely described with the following equation: Δlog kortho = log kortho ? log kH = 1.57σI + 0.93σ°R + 1.08EsB ? 0.030ΔEσI ? 0.069ΔEσ°R, where ΔE is the solvent electrophilicity, ΔE = ES ? EH20, characterizing the hydrogen‐bond donating power of the solvent. We found that the experimental log k values for ortho‐, para‐ and meta‐substituted phenyl benzoates in aqueous 50.9% acetonitrile at 25 °C, determined in the present work, precisely coincided with the log k values predicted with the equation (log kX)calc = (log kHAN)exp + (Δlog kX)calc where the substituent effect (Δlog kX)calc was calculated from equation describing the variation of the substituent effect with the solvent electrophilicity parameter, using for aqueous 50.9% CH3CN the solvent electrophilicity parameter, ΔE = ?5.84. In going from water to aqueous 50.9% CH3CN, the ortho inductive term grows twice less as compared with the para polar effect. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

17.
结晶紫和结晶紫母体在强有机酸中,其甲基峰都移向低场。在取代的芳烃溶剂中,甲基峰都移向高场,而且彼此间的化学位移有线性关系,并与Hammett取代基常数及改正的Hammett取代基常数间有线性关系。讨论了电子移动度的应用以及取代基常数σ与σ~-间的线性关系。  相似文献   

18.
双丙酮丙烯酰胺的紫外光谱研究   总被引:2,自引:0,他引:2  
双丙酮丙烯酰胺(DAAM)是一种应用广泛的聚合物单体,可与其他乙烯基单体共聚得到性能各异的聚合物材料,而对DAAM的光谱研究报道较少。文章主要研究了DAAM在水、乙腈、甲醇和环己烷四种溶剂中的紫外光谱。结果发现,在这四种溶剂中,DAAM溶液的紫外光谱主要在200 nm左右及226 nm左右有2个强吸收峰。200 nm左右的吸收峰对溶剂的极性及溶液的浓度非常敏感。在极性溶剂中200 nm吸收峰发生蓝移,在极性较大的乙腈及水中,蓝移更大;在各种溶剂中,200 nm吸收峰都随溶液浓度增大而发生红移。而226 nm左右的吸收峰在各种极性不同的溶剂中吸收峰的位置变化不明显,对溶液浓度也不敏感。因此,DAAM在226 nm吸收峰可以用于DAAM的定量分析,而200 nm吸收峰可用于研究DAAM与其他分子的相互作用。另外,溶剂极性对2个吸收峰强度的影响也不相同。  相似文献   

19.
齐德林  王东 《波谱学杂志》1991,8(2):187-194
结晶紫和结晶紫母体在强有机酸中,其甲基峰都移向低场。在取代的芳烃溶剂中,甲基峰都移向高场,而且彼此间的化学位移有线性关系,并与Hammett取代基常数及改正的Hammett取代基常数间有线性关系。讨论了电子移动度的应用以及取代基常数σ与σ-间的线性关系。  相似文献   

20.
DFT computations were performed on the SN1 and SN2 solvolyses of substituted cumyl chlorides and benzyl chlorides in ethanol and water, by increasing stepwise the C? Cl distance and by optimization. The total energy increases with the increase in the Cl? C distance in SN1 reactions, while free energy of activation pass through maximum. To validate the results, the calculated free energies of activation were compared with data obtained by kinetic measurements. The structural parameters of the transition states were correlated with the Hammett substituent constants and compared with the data of hydrolyses of tert‐butyl chloride and methyl chloride, which proceed with known mechanisms. Conclusions on the mechanisms of the reactions were driven from the effect of substituents on free energies of activation. Cumyl chlorides substituted with electron‐donating (e‐d) groups solvolyze with SN1 mechanism, while the reactions of substrates that bear electron‐withdrawing groups proceed with weak nucleophilic assistance of the solvent. Benzyl chlorides hydrolyze through an SN2 pathway except those derivatives that have strongly e‐d groups, where the reaction has SN1 character, but a weak nucleophilic assistance of the water should also be taken into consideration. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

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