电荷转移复合物和光诱导电荷转移聚合

讨论了电子受体和给体的强弱与形成基态、激发态电荷转移复合物的性质、类型等的关系。着重讨论了氧与有机化合物分子形成的接触电荷转移复合物及烯类单体与电子给体或受体形成的光诱导电荷转移复合物。讨论了使烯类单体发生光诱导电荷转移聚合和电子给体的分子结构对它的影响;并从形成激基复合物的观点对自由基阻聚剂酚噻嗪在光照下失去阻聚能力作了解释。     

乙腈溶液中NO3自由基与联苯的反应机理

以硝酸铈铵乙腈溶液激光闪光光解产生的NO3自由基在无氧条件下与联苯作用,采用瞬态光谱技术和GC-MS技术分别对反应过程中产生的中间瞬态产物以及反应的最终产物进行了分析,对反应历程作了明确推断.研究表明,NO3自由基首先从联苯的苯环上夺取电子形成电荷转移复合物,二级反应速率常数为8.24×109L·mol-1·s-1;进而通过消除反应在苯环上定位形成邻-硝基联苯和对-硝基联苯,电荷转移复合物衰减表观的一级反应速率常数为2.30×105s-1.     

三硝基苯-对位取代苯酚负离子荷移复合物从头算研究

运用G94W量子化学程序,在HF/3-21G基组水平上对三硝基苯-对位取代苯酚(取代基:CH~3O-,CH~3-,Cl-)负离子的电荷转移复合物进行从头计算。把电荷转移复合物看成一个超分子,研究该系列复合物的稳定性、电荷转移及几何构型等规律。计算结果表明,苯酚负离子供电中心O沿一倾角指向三硝基苯中的任意相邻两个硝基之间的C位置上,复合物的稳定性按对位取代苯酚取代基CH~3O-,CH~3-,Cl-的次序减小,与实验规律相一致。计算结果还表明,形成该系列复合物具有明显的电荷转移,其稳定性与电荷转移量有关等。     

有机固体电导性的研究 Ⅰ.N-烷基-2-氨基吡啶季铵盐与7,7,8,8-四腈代对苯醌二甲烷的电荷转移复合物的研究

我们以2-氨基吡啶与五种卤代烷反应,制得相应的N-烷基-2-氨基吡啶季铵盐卤化物,再与7,7,8,8-四腈代对苯醌二甲烷(TCNQ)或与锂-7,7,8,8-四腈代对苯醌二甲烷(LiTCNQ)反应,得到离子自由基型电荷转移复合物。对1:1复合物及1:2复合物的制备、紫外-可见吸收光谱、顺磁性及电导性进行了研究。结果表明,在乙腈中生成1:2复合物,而不生成1:1复合物;季铵盐上烷基较大时(如C₄H₉,C₅H₁₁),由于空间阻碍效应,在溶剂中不易生成1:2复合物,不易结晶;烷基大小对生成电荷转移复合物的电导率有影响。这类单盐和复盐用紫外-可见吸收光谱及顺磁共振谱很易鉴别。     

乙腈溶液中NO3自由基与联苯的反应机理

以硝酸铈铵乙腈溶液激光闪光光解产生的NO₃自由基在无氧条件下与联苯作用,采用瞬态光谱技术和GC-MS技术分别对反应过程中产生的中间瞬态产物以及反应的最终产物进行了分析,对反应历程作了明确推断.研究表明,NO₃自由基首先从联苯的苯环上夺取电子形成电荷转移复合物,二级反应速率常数为8.24×10⁹L·mol^-1·s^-1;进而通过消除反应在苯环上定位形成邻-硝基联苯和对-硝基联苯,电荷转移复合物衰减表观的一级反应速率常数为2.30×10⁵s^-1.     

电子给受体复合物中电荷转移吸收光谱和溶剂效应

用MP2/6-31G^**方法研究了二氯甲烷溶剂分子与电子给体、受体以及电子给受体复合物间的相互作用,结果表明,二氯甲烷与电子受体和电子给受体复合物间有弱氢键相互作用.利用CIS/6-31++G^**方法研究了溶剂与溶质分子间形成氢键对激发态的影响.自然键电荷分析表明,电子给受体复合物的S₀→S₁跃迁导致一个电子从电子给体转移到受体.结合非平衡溶剂化处理和自洽反应场方法研究了溶剂分子与复合物间形成氢键时的电荷转移吸收光谱.计算表明氢键作用导致复合物的电荷转移吸收光谱蓝移.     

2-乙烯基萘/反丁烯二腈光照下共聚合

2-乙烯基萘与反丁烯二腈可以在365nm光照下共聚合,生成1:1交替共聚物。研究了聚合反应的引发机理,认为通过二者的基态电荷转移复合物受光激发和2-乙烯基萘的定域激发形成激发态复合物,其进一步反应生成1,4-双自由基,引发链增长。     

α-蒎烯的光氧化反应研究

α-蒎烯和氧能在基态条件下形成CCT复合物,在与CCT复合物吸收相应波长的光辐照下,有利于促进蒎烯的光氧化反应。在氧化反应中,存在着明显的溶剂极性的影响,极性愈大,反应的速度愈快。这一切都说明电荷转移在反应中起着重要的作用。此外,正由于存在着基态的CCT复合物,因此α-蒎烯的氧化反应也能在暗的条件下进行。根据蒎烯光氧化和暗氧化反应产物的分析,可以肯定蒎烯在本工作实验条件下的氧化反应是通过自由基机理而进行的。     

芳环光取代反应的单电子转移模式

基于实验观察和反应物的MO计算, 发现长波长光照下的SRN1反应活性与电子加到ArX-LUMO的难易程度有关, 由ArBr和碳负离子形成的基态电荷转移复合物的激发可能是SRN1光诱导的主要通道。     

电荷转移复合物的量子化学研究(1)列—1,3,5-三硝基苯与对位取代苯酚钾系

用CNDO/2法对1,3,5-三硝基苯与苯酚钾系列的电荷转移复合物作了研究以解释该系列稳定性的实验规律并探讨其稳定构型。在溶液中形成电荷转移复合物联系着不少生命过程,故颇受研究者重视。例如Wallwork利用X-光数据讨论了三硝基苯与一些芳烃生成的复合物的构型。仅能在溶液中存在的复合物则宜用量子化学法,例如严继民等用EHMO法计算苯与四氰乙烯生成的复合物以研究其构型。     

Theoretical Study on the Dark Oxidation Reaction Mechanism of Ethers

1 INTRODUCTION Ethers are a kind of organic compounds that are easily oxidized under the conditions of lacking light and any additional excitement. According to dif- ferent mechanisms, the oxidation reactions could be classified into two types: photooxidation reaction and dark oxidation reaction. The former is the reaction with excited state oxygen molecule (singlet state), while the latter is the reaction with ground state oxygen molecule (triple state) without illuminance or any exciter…     

气相芳香亲电取代反应研究进展

对气相芳香亲电取代反应的一般机理、小碎片正离子的亲电取代反应特性、反应中间体结构及质子在芳香环内和芳香环间的迁移反应作了评述。     

N-芳基马来酰亚胺与硫代硫酸钠的电荷转移络合物研究

本文以硫代硫酸根离子作为电荷给体(D),系列N-芳基取代马来酰亚胺(RPhMI)作为电荷受体(A),用含水5%的二甲基亚砜(95%DMSO)为溶剂,以紫外可见分光光度法研究了RPhMI与S₂O₃^2-作用生成的电荷转移(CT)络合物。以其CT光谱计算了RPhMI的电子亲合能(E_A).测定了CT络合物的生成常数K.结果显示,弱的受体N-马来酰亚胺与强的给体硫代硫酸根负离子可以生成稳定的CT络合物。文章还讨论了CT络合物的可能结构及取代基极性与CT络合物的稳定性关系。     

Spectrophotometric study on the charge transfer reaction between 2-amino-4-methylpyridine with chloranilic acid in polar solvents

Charge transfer (CT) complexes formed between 2-amino-4-methylpyridine as electron donor, chloranilic acid as electron acceptor was investigated spectrophotometrically in acetonitrile (AN), methanol (MeOH) and binary mixture of acetonitrile 50% + methanol 50% (MeOH-AN). Minimum–maximum absorbance method has been used for estimating the formation constants of the CT reactions (K_CT). Job’s method of continuous variation and photometric titration studies were used to detect the stoichiometric ratios of the formed complexes, and they showed that 1:1 complexes were produced. The molar extinction coefficient (e), oscillator strength (f), dipole moment (l), CT energy (E_CT), ionisation potential (I_P) and the dissociation energy (W) of the formed complexes were estimated; they reached acceptable values suggesting the stability of the formed CT complexes. The solid CT complexes were synthesised and characterised by elemental analyses, ¹H NMR and FTIR spectroscopies where the formed complexes included proton and electron transfer.     

Equilibrium shift in the rhodium-catalyzed acyl transfer reactions

Rhodium/phosphine complexes catalyze equilibrium acyl transfer reactions between acid fluorides, aryl esters, acylphosphine sulfides, and thioesters. The use of appropriate co-substrates to accept heteroatom groups shifted the equilibrium to desired products. Acylphosphine sulfides and aryl esters were converted to acid fluorides using benzoylpentafluorobenzene as the fluoride donor, and the fluorination reaction of thioesters employed (4-tolylthio)pentafluorobenzene. Acid fluorides were converted into acylphosphine sulfides and thioesters using diphosphine disulfides and disulfides/triphenylphosphine, respectively. Aryl esters were obtained from acid fluorides and phenols in the presence of triphenylsilane. Aryl esters, acylphosphine sulfides, and thioesters were also interconverted in the presence of rhodium complexes. These rhodium-catalyzed acyl transfer reactions proceeded under neutral conditions without using acid or base. The involvement of acyl rhodium intermediates in these reactions was suggested by the carbothiolation reaction of thioesters and alkynes.     

Inner Sphere Reorganization Energy for the Electron Transfer Reactions between M-C_6H_6 and M~ -C_6H_6 Complexes in Gaseous phase: An ab initio Computation

IntroductionTheelectrontransfer(ET)reactionisanfundamentalchemicalprocessandhasbecomethefocusoftheoreticalandexperimentalstudies1-3.AsuitableapproachtowardunderstandingtheETreactivitypatternsistoseparatethevariouscontributionsintoexponentialandpre-exponentialfactors.Theexponentialparts,i.e.,theFrank-Condonfactor,isacompositeofthestructuralreorganizationofthereactingsystemimmediate1yaftertheelectrontransfered.Basedonthecharacteristicsofthereactingsystem'sstructure,thereorganizationenergy(RE…     

Electron-transfer reduction of dinuclear copper peroxo and bis-μ-oxo complexes leading to the catalytic four-electron reduction of dioxygen to water

The four-electron reduction of dioxygen by decamethylferrocene (Fc*) to water is efficiently catalyzed by a binuclear copper(II) complex (1) and a mononuclear copper(II) complex (2) in the presence of trifluoroacetic acid in acetone at 298 K. Fast electron transfer from Fc* to 1 and 2 affords the corresponding Cu(I) complexes, which react at low temperature (193 K) with dioxygen to afford the η(2):η(2)-peroxo dicopper(II) (3) and bis-μ-oxo dicopper(III) (4) intermediates, respectively. The rate constants for electron transfer from Fc* and octamethylferrocene (Me(8)Fc) to 1 as well as electron transfer from Fc* and Me(8)Fc to 3 were determined at various temperatures, leading to activation enthalpies and entropies. The activation entropies of electron transfer from Fc* and Me(8)Fc to 1 were determined to be close to zero, as expected for outer-sphere electron-transfer reactions without formation of any intermediates. For electron transfer from Fc* and Me(8)Fc to 3, the activation entropies were also found to be close to zero. Such agreement indicates that the η(2):η(2)-peroxo complex (3) is directly reduced by Fc* rather than via the conversion to the corresponding bis-μ-oxo complex, followed by the electron-transfer reduction by Fc* leading to the four-electron reduction of dioxygen to water. The bis-μ-oxo species (4) is reduced by Fc* with a much faster rate than the η(2):η(2)-peroxo complex (3), but this also leads to the four-electron reduction of dioxygen to water.     

2，5－二甲氧基苯基烷基酮与t－BuMgCl反应的机理研究

２，５－二甲氧基苯基烷基酮１_（ａ－ｄ）（烷基分别为甲基、乙基、异丙基和叔丁基）与ｔ－ＢｕＭｇＣｌ反应后，主要生成了１，２－加成产物、１．６－共轭加成产物及还原产物，产物及其分布在不同程度上受酮的结构、反应介质以及金属镁中过渡金属杂质的含量等因素的影响。据此，提出了反应的可能机理。     

2,5-二甲氧基苯基烷基酮与t-BuMgCl反应的机理研究

2,5-二甲氧基苯基烷基酮1_(a-d)(烷基分别为甲基、乙基、异丙基和叔丁基)与t-BuMgCl反应后,主要生成了1,2-加成产物、1.6-共轭加成产物及还原产物,产物及其分布在不同程度上受酮的结构、反应介质以及金属镁中过渡金属杂质的含量等因素的影响。据此,提出了反应的可能机理。     

Charge transfer complexes between 4,4′-disubstituted diphenyldiacetylenes: experimental and theoretical study

Novel charge transfer (CT) complexes containing donor and acceptor derivatives of diphenyldiacetylene have been synthesised and characterised. The structure of CT complexes was modelled at the B3LYP/6-31G(d)//B3LYP/6-31G(d) level of theory. It was found that the complex formation is mainly due to dipole–dipole interaction between side groups of diacetylene molecules and there was no significant charge transfer between donor and acceptor in the ground state. On the other hand, optical excitation of CT complexes leads to strong charge transfer from donor to acceptor molecule as followed from the modelling using time-dependent density functional theory (DFT) method. Diacetylene molecules adopt strongly bent configuration in CT complexes which is prohibitive for solid-state topochemical polymerisation of diacetylenes