2,2,6,6-四甲基哌啶氧铵盐与吩噻嗪类化合物单电子转移反应动力学——Marcus理论的应用

2 ,2 ,6 ,6 四甲基哌啶氧铵盐 ( 1a ,1b)与吩噻嗪类化合物 ( 2a～ 2g)迅速反应 ,生成相应的氮氧自由基 ( 3a ,3b)和吩噻嗪类化合物的正离子自由基 ( 4a～ 4g) .通过EPR和NMR的谱线增宽效应 ,测定了乙腈中 1和 3以及 2和 4之间的电子自交换反应速率常数 ,应用Marcus理论研究了 1和 2之间的反应动力学     

吩噻嗪、N-甲基吩噻嗪及其自由基正离子的结构和电子光谱的理论研究

用INDO系列方法对吩噻嗪、N-甲基吩噻嗪及其自由基正离子进行了几何构型优化,中性分子为蝶状折叠形,自由基正离子为平面构型.以优化构型为基础,计算了上述四种分子、离子的电荷密度、自旋密度、键序和电子光谱,对光谱进行理论指认的同时,讨论了从中性分子到离子谱带红移的原因.所有理论计算值均与实验值一致.     

N—乙基吩噻嗪及其自由基正离子的结构和电子光谱的理论研究

用ＩＮＤＯ系列方法对Ｎ－乙基吩噻嗪及其自由基正离子进行了几何构型优化，得到中性分子为蝶状折叠形，自由基正离子为平面构型，以优化构型为基础计算其电荷密度，自旋密度键序和电子光谱。对光谱进行理论指认并讨论了从中性分子到离子谱带红移的原因，理论计算结果法与实验结果一致。     

吩噻嗪、N-甲基吩噻嗪及其自由基正离子的结构和电子光谱的理论研究

用INDO系列方法对吩噻嗪、N-甲基吩噻嗪及其自由基正离子进行了几何构型优化, 中性分子为蝶状折叠形, 自由基正离子为平面构型。以优化构型为基础,计算了上述四种分子、离子的电荷密度、自旋密度、键序和电子光谱, 对光谱进行理论指认的同时, 讨论了从中性分子到离子谱带红移的原因。所有理论计算值均与实验值一致。     

β-环糊精负载四甲基哌啶氮氧化物的合成及其在分子氧氧化醇反应中的催化性能

以乙烯基二胺为连接臂将四甲基哌啶氮氧化物(TEMPO)负载于β-环糊精(β-CD)上,得到负载型催化剂β-CD-TEMPO.采用~1H NMR、~(13)C NMR以及FT-IR等手段对β-CD-TEMPO进行了表征.将β-CD-TEMPO、CuBr_2以及K_2CO_3结合构成催化体系,用于分子氧为氧化剂的醇的选择性氧化反应,结果表明该体系对苄基以及烯丙基伯醇的氧化显示出良好的催化活性和选择性.在负载催化剂中,乙烯基二胺既作为连接臂又作为配体与铜离子配位,使氧化反应顺利进行.负载型催化剂β-CD-TEMPO与产物容易分离,能够循环使用.     

电子转移的外电场效应──苯分子与苯正离子自由基间电子转移的从头算研究

基于半经典电子转移理论,结合量子化学计算,在HF/DZP水平上,研究外电场作用下平行的苯分子-苯正离子自由基体系(C₆H₄)₂⁺的分子内电子转移问题.在给体和受体几何构型优化的基础上,用线性反应坐标确定电子转移过渡态,分别用两态变分方法和基于Koopmans定理的分子轨道跃迁能方法计算电子转移矩阵元V_AB,讨论了V_AB对给体和受体中心距d的指数衰减关系.取中心距为0.6nm,研究了外电场对反应热的影响,计算得到在不同外电场强度下分子内气相电子转移的速率常数k.     

电子转移的外电场效应——苯分子与苯正离子自由基间电子 …

基于半经典电子转移理论，结合量子化学计算，城ＨＦ／ＤＺＰ水平上，研究外电场作用下平行的苯分子－苯正离子自由基体系（Ｃ６Ｈ４）２＾＋的分子内电子转移问题。在给体和受体几何构型优化的基础上，用线性反应坐标确定电子转移过渡态，分别用两态变分方法和基于Ｋｏｏｐｍａｎｓ定理的分子轨道跃迁能方法计算电子转移矩阵元ＶＡＢ，讨论了ＶＡＢ对给体和受体中心距ｄ的指数衰减关系，取中心距为０．６ｎｍ，研究了外电场对反应热     

三乙胺与2-氯-5-甲氧基对苯醌光电子转移反应的CIDNP研究

用化学诱导动态核极化（CIDNP）方法研究了三乙胺与2-氯-5-甲氧基对苯醌在 C6D6，CH3CN溶剂中的反应机理，实验结果表明反应过程中首先形成基态电荷转移 络合物（CTC），在CD3CN中，光照电荷分离形成离子自由基对，使三乙胺亚甲基产 生发射极化信号。同时用UV-vis实验证实CTC的存在。     

Electron diffraction study of the molecular structure of gaseous 1,1-dibromo-3,3,5,5-tetramethyl-1-stanna-3,5-disila-4-oxacyclohexane,Br2Sn(CH2SiMe2)2O

The molecular structure of gaseous Br₂Sn(CH₂SiMe₂)₂O was studied by electron diffraction. The six-membered ring has a chair conformation whereas the entire molecule possessesC _s symmetry. The existence of a boat conformer cannot be completely excluded. The results of theoretical calculations for a twisted-boat conformation are at variance with the experimental data. Steric strain caused by mutual repulsion of the two axial methyl groups is reduced to the tilt of the Me₂Si fragments in opposite directions. This results in an increase (up to 26°C) in the angle formed by the bisector of the C_M-Si-C_M angle with the C_cSiO plane. The main geometrical parameters are as follows:r _g (Å): Si-O 1.708(20); Si-C_M 1.862(20); Si-C_c 1.882(9); Sn-C 2.108(26); Sn-Br 2.456(3); C-H 1.099(30); (degr.): C-Sn-C 105(2); Br-Sn-Br 107.9(1.2); Si-O-Si 129.6(3); C_M-Si-C_M 112; Si-C-H 113 (fixed value in accordance with experiment); C_c-Si-O 107(2); Sn-C-Si 109(2); torsion angles: (Si-C) 52(2); (Si-O) 62(1); (C_c-Sn) 54(1). The average amplitudes were fixed at the values calculated from the force field. Structural parameters of molecules with similar structures were analyzed and compared.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 384–387, February, 1993.     

Electron Transfer Reaction Between Desoxyadenosine and Triplet 2-Methyl-l, 4-naphthaquinone： A Laser Photolysis Study

Introduction Electron transfer oxidation of DNA by triplet artificial photonuclease reveals a bright prospect of its application in biology and medicine. Both molecular orbital calculation and laser experiments have indicated that the homo guanine sequence should be the final localization site of photoexcited hole via long range migration within DNA. However, the direct observation of the produced ion pairs of biomolecules especially the stabilized radical cation DNA or its components is hampered by the overwhelming transient absorption of protonated radical anion of photosensitizers, such as 2-methyl-1,4-naphthaguinonel （MQ）.     

Electron Transfer Reaction Between Desoxyadenosine and Triplet 2-Methyl-1,4-naphthaquinone:A Laser Photolysis Study

Introduction ElectrontransferoxidationofDNAbytripletartifi cialphotonucleaserevealsabrightprospectofitsappli cationinbiologyandmedicine.Bothmolecularorbital calculationandlaserexperimentshaveindicatedthat thehomoguaninesequenceshouldbethefinallocaliza tio…     

Theoretical Study on the NO2＋NO2^— Electron Transfer Reaction

The NO2 NO2^- electron transfer reaction was studied with DFT-B3LYP method at 6-311 G^* basis set level for the eight selected structures:four species favor the structure of “head to head”.The geometry of transition state was obtained by the linear corrdinate method.Three parameters,non-adiabatic activation energy(Ead),coupling matrix element(Hif) and reorganization energy(λ) for electron transfer reaction can be calculated.According to the reorganization energy of the ET reaction,the values obtained from George-Griffith-Marcus (GGM) method(the contribution only from diagonal elements of force constant matrix) are larger than those obtained from Hessian matrix method(including the contribution from both diagonal and off-diagonal elements), which suggests that the coupling interactions between different vibrational modes are important to the inner-sphere reorganization energy for the ET reactions in gaseous phase.The value of rate constant was obtained by using above three activation parameters.     

Reaction of 2-substituted 4-oxo-5, 6-benzo-1, 3, 2-dioxaphosphorinanes with ethyl pyruvate

The reaction of 2-substituted 4-oxo-5, 6-benzo-1, 3, 2-dioxaphosphorinanes with ethyl pyruvate affords ring-expansion products, i.e., diastereomeric 2-substituted 2, 5-dioxo-6, 7benzo-1, 3, 2-dioxaphosphepanes.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 565–567, March, 1993.The authors are grateful to Ye.I.Gol'dfarb for recording the 31_P-(1_H) NMR spectra.     

三氯化铝催化1,1,2,2-四甲基-1,2-二氯二硅烷的裂解机理研究

采用DFT和MP2方法对1,1,2,2-四甲基-1,2-二氯二硅烷的催化裂解机理进行了研究. 结果表明, 催化剂三氯化铝先与二硅烷反应, 生成中间产物后再与裂解气三氯甲烷作用并生成产物. 反应分3步进行, 各步活化能分别为: 152.543, 79.322和128.889 kJ•mol^－1. 速控步为第一步反应, 3步的焓变分别为: 83.785, －275.771和－120.712 kJ•mol^－1, 总焓变为－312.698 kJ•mol^－1, 即为放热的. 反应的标准摩尔吉布斯自由能为－306.462 kJ•mol^－1, 裂解反应的平衡常数 ＝4.9295×10⁵³, 在常温常压下反应的理论产率较高, 与实验结果一致.     

Reaction of 1, 1-Di-p-methoxyphenyl-2, 2-dinitroethylene and 1, 1-Di-O-methoxyphenyl-2, 2-dinitroethylene with 1-Benzyl-1, 4-dihydronicotinamide： Evidence for Concerted Electron-hydrogen Atom Transfer Mechanism

1,1-Di-p-methoxyphenyl-2, 2-dinitroethylene reacts with 1-benzyl-1, 4-dihydronicotinamide (BNAH) in deaerated acetonitrile to give 1,1-di-p-methoxyphenyl-2, 2-dinitroethane,while 1,1-di-O-methoxyphenyl-2, 2-dinitroethylene fails to react with BNAH under the same conditions, which provides evidence for a concerted electron-hydrogen atom transfer mechanism.     

Theoretical Study on the Kinetics of Electron Transfer for Bond—breaking Reaction

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新试剂6-(2,4-二羟基苯基偶氮)-2,3-二氢-1,4酞嗪二酮的电致化学发光研究

本文研究了6-(2,4-二羟基苯基偶氮)-2,3-二氢-1,4酞嗪二酮(新试剂DHDHD)的电致化学发光的条件及产生电化学发光的机理。