加成基团对富勒烯电化学性质的影响

采用循环伏安法和微分脉冲伏安法对比地研究了包括五种Ｃ６０的衍生物及四种Ｃ７０的衍生物的电化学性质。结果表明，推电子基团的引入使得富勒烯的氧化还原电位负移，这种负移的程度与加成基团的性质，个数和富勒烯的性质有关。     

含磷C_(60)衍生物的电化学性能研究

利用循环伏安法测试了 3种新合成的C60 膦酸酯衍生物的电化学性能 .通过比较不同取代基的C60 衍生物的电化学性能 ,研究引入基团的结构特性与其得电子能力之间的关系     

香豆素及其衍生物在二甲基亚砜中的电还原性质

采用循环伏安法对香豆素及其衍生物的电还原进行研究；香豆素的电还原发生在羰基上；如果香豆素衍生物分子上含有吸电子基团，则还原电位正移；如果含有给电子基因，则还原电位负移；如果同时含有吸电子和给电子基因，则表现综合结果。     

1,2-H(XPhCH2)C60衍生物中取代基团对NMR及电化学性质的影响

为了考察取代基团对C60衍生物性质的影响,分别进行了一系列1,2-H(XPhCH2)C60(X=H,o-CH3,m-CH3,p-CH3,o-Br,m-Br,p-Br)的1H NMR、13C NMR和电化学循环伏安测试。 结果表明,邻位取代基团对苄基中亚甲基氢原子和碳原子的核磁响应具有较大的影响,而取代基团位置对C60-H和C60sp3碳原子核磁响应影响较小;在循环伏安中,苄基上的-CH3和-Br基团位置对C60衍生物的氧化还原电势并未表现出显著影响,但与1,2-H(PhCH2)C60相比,所有具有CH3PhCH2-基团的化合物氧化还原电势均表现出负移,而具有BrPhCH2-基团的化合物氧化还原电势均表现出正移,表明诱导效应是影响C60衍生物性质的主要因素,因此,可通过调控衍生物的电子结构来探究其性质。     

Effect of Addition Groups on the Redox Properties of Fullerenes

采用循环伏安法和微分脉冲伏安法对比地研究了包括五种Ｃ６０的衍生物及四种Ｃ７０的衍生物的电化学性质．结果表明，推电子基团的引入使得富勒烯的氧化还原电位负移，这种负移的程度与加成基团的性质、个数和富勒烯的性质有关．对于Ｃ６０和Ｃ７０的单加成产物，负移的范围是０．０８～０．２０Ｖ．而对于Ｃ６０的双加成和三加成产物负移的范围分别为０．３０～０．３２Ｖ和０．５３～０．５８Ｖ．同时由于电位的负移大部分衍生物在低于＋１．５Ｖ（ｖｓ．ＳＣＥ）观察到了氧化峰，而Ｃ６０和Ｃ７０本身的氧化高达＋１．７Ｖ（ｖｓ．ＳＣＥ）．特别是对于Ｃ７０的双加成产物在＋０．４５Ｖ（ｖｓ．ＳＣＥ）出现了一个不可逆氧化峰，但是，对于同样加成基团的Ｃ６０双加成产物的氧化却在＋０．９０Ｖ（ｖｓ．ＳＣＥ），说明由于推电子基团的双加成引入，明显改变了Ｃ７０的电负性．     

C60负离子化学的研究进展

中性的C60是很强的缺电子体,主要和亲核试剂进行化学反应.与之不同的是C60经还原生成负离子后,由缺电子变为富含电子,具有很强的亲核性质,可与亲电试剂进行反应.由于这种电子结构的变化,C60负离子进行的反应从机理至产物均有可能与中性富勒烯不同.从而丰富了富勒烯的反应方式和富勒烯产物的类型.结合我们的工作综述了C60负离子化学的研究进展,对丰富富勒烯化学、扩展富勒烯衍生物的种类及制备方法具有一定意义.     

辅酶B_(12)模型化合物的研究 α.RCo(salen) L(R=n-C_3H_7,i-C_4H_9;L=H_2O,py,γ-pic)的电化学性质

用循环伏安法研究了辅酶 B1 2 模型化合物 RCo(salen) L (R=n- C3 H7,i- C4H9;L=H2 O,py,γ-pic)的电化学行为 ,讨论了轴向碱基 L对氧化还原电位的影响。结果表明 :随着碱基 L给电子能力的增强 ,其氧化还原电位均发生负移。     

三苯基咪唑富勒烯吡咯烷衍生物的合成及其紫外、荧光和光限幅性质的研究

通过1,3-偶极环加成合成了四种三苯基咪唑富勒烯吡咯烷衍生物3a～3d,用FT-IR,NMR,MS和元素分析进行其结构测定和表征;用循环伏安法测定了其电化学性质,结果表明,与参比化合物C60相比还原电位发生负移,更容易形成电子受体;用纳秒和飞秒激光研究了四种化合物的光限幅性质,结果表明化合物3a和3c的纳秒光限幅性质明显,而3b则观察不到光限幅现象,说明化合物中硝基的引入不利于光限幅效应.     

含C60的苯乙烯和丙烯酰胺共聚物的合成与表征

在高分子领域中,C60的高分子化一直是C60材料化的一个重要途径.迄今为止,制备含C60高分子的方法有以下几种:(1)采用自由基引发剂、阴离子引发剂或阳离子引发剂引发C60与烯类单体共聚[1,2];(2)对C60进行表面修饰,引入可聚合官能团,合成含C60的单体,随后聚合成含C60的高分子[3];(3)制备出带有功能基团的高分子前体,再通过功能化反应将C60引入高分子链[4～9].     

单加成环丙烷富勒烯膦酸酯衍生物的合成与电化学性能

在Mn(OAc)₃•2H₂O催化下, C₆₀分别和亚甲基二膦酸四乙酯、氰基亚甲基膦酸二乙酯或乙氧羰基亚甲基膦酸二乙酯在氯苯中回流, 生成3个单加成环丙烷富勒烯膦酸衍生物C₆₀C(R)PO(OEt)₂ [1, R＝PO(OEt)₂; 2, R＝COOEt; 3, R＝CN]. 与以前报道的Bingel反应法相比, 该方法副产物少并且缩短了反应时间. 采用循环伏安法发现1, 2的还原电位相对于C₆₀发生负移, 而3的还原电位相对于C₆₀却正移40 mV, 表明引入象氰基一样具有很强吸电子能力的取代基团, 可以改善富勒烯球的电化学性能, 合成电子接受能力较强的富勒烯衍生物.     

Electronic Tuning of Mixed Quinoidal‐Aromatic Conjugated Polyelectrolytes: Direct Ionic Substitution on Polymer Main‐Chains

The synthesis of conjugated polymers with ionic substituents directly bound to their main chain repeat units is a strategy for generating strongly electron‐accepting conjugated polyelectrolytes, as demonstrated through the synthesis of a series of ionic azaquinodimethane (iAQM) compounds. The introduction of cationic substituents onto the quinoidal para‐azaquinodimethane (AQM) core gives rise to a strongly electron‐accepting building block, which can be employed in the synthesis of ionic small molecules and conjugated polyelectrolytes (CPEs). Electrochemical measurements alongside theoretical calculations indicate notably low‐lying LUMO values for the iAQMs. The optical band gaps measured for these compounds are highly tunable based on structure, ranging from 2.30 eV in small molecules down to 1.22 eV in polymers. The iAQM small molecules and CPEs showcase the band gap reduction effects of combining the donor‐acceptor strategy with the bond‐length alternation reduction strategy. As a demonstration of their utility, the iAQM CPEs so generated were used as active agents in photothermal therapy.     

Length of Soliton Wave in the Excited State in the Cations of Symmetrical Pyridocyanines and Their Carbo and Hetero Analogs

Quantum-chemical calculations in the AM1 approximation were undertaken for the optimized geometry of the cations of polymethine dyes [R⁺—(CH=CH) _n —CH=R], where R represents phenyl substituents or pyridinium, pyrylium, and thiopyrylium groups and n = 1-6, in the ground state and for the electron density distribution in the Frank – Condon excited state. It was found that excitation of the molecule by a light quantum leads to a decrease in the length of the charge wave (soliton). It was shown that the length of the soliton depends on the electron-donating character of the terminal groups R and on the length of the conjugated chain, while shortening of the soliton in the thiopyrylocyanines leads to disruption of its symmetry.     

C_(60)与含受电子生色基团聚合物的电荷转移现象

Ｃ６０与含受电子生色基团聚合物的电荷转移现象邱健姚光庆周锡煌李福绵（北京大学化学与分子工程学院北京１００８７１）关键词Ｃ６０，聚［Ｎ （４ 氰基苯基）丙烯酰胺］，电荷转移现象，荧光光谱随着对球壳烯性质的深入认识，球壳烯与电子给、受体的电荷转移现象日...     

Formazanate Complexes of Hypervalent Group 14 Elements as Precursors to Electronically Stabilized Radicals

The stability of molecular radicals containing main‐group elements usually hinges on the presence of bulky substituents that shield the reactive radical center. We describe a family of Group 14 formazanate complexes whose chemical reduction allows access to radicals that are stabilized instead by geometric and electron‐delocalization effects, specifically by the square‐pyramidal coordination geometry adopted by the Group 14 atom (Si, Ge, Sn) within the framework of the heteroatom‐rich formazanate ligands. The reduction potentials of the Si, Ge, and Sn complexes as determined by cyclic voltammetry become more negative in that order. Examination of the solid‐state structures of these complexes suggested that their electron‐accepting ability decreases with increasing size of the Group 14 atom because a larger central atom increases the nonplanarity of the ligand‐based conjugated π‐electron system of the complex. The experimental findings were supported by density‐functional calculations on the parent complexes and the corresponding radical anions.     

Electrochemical reduction of some methanofullerenes. On the mechanism of the retro-Bingel reaction

The reactions of electrochemical reduction of methanofullerenes bearing phosphonate and alkoxycarbonyl groups at theexo-carbon atom were studied. The mechanism of the retro-Bingel reaction as the cleavage of two C−C bonds between the C(61) atom and the fullerene shell accompanied by electrochemical electron transfer was proposed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 426–429, March. 2000.     

中性富勒烯分子的直接电喷雾质谱分析

电喷雾电离是新近发展的一种质谱技术, 适用于分析在溶液中呈离子状态的物质, 具有无碎片的特点。本文根据富勒烯分子的电子亲和性能, 将富勒烯混合物的甲苯溶液直接进行电喷雾质谱分析, 检出了C60, C70, C76, C80, C82, C84, C86,C88, C90, C92, C94和C96等的负离子峰。并用萘钾作还原剂,将富勒烯混合物预先还原, 制得富勒烯负离子溶液后再作电喷雾质谱分析, 得到相同的结果。表明各类富勒烯分子在电喷雾过程中俘获电子的能力与被萘钾还原的能力相一致。     

One-electron oxidation and reduction potentials of nitroxide antioxidants: a theoretical study

High-level ab initio calculations have been used to determine the oxidation and reduction potentials of a large number of nitroxides including derivatives of piperidine, pyrrolidine, isoindoline, and azaphenalene, substituted with COOH, NH2, NH3+, OCH3, OH, and NO2 groups, with a view to (a) identifying a low-cost theoretical procedures for the determination of electrode potentials of nitroxides and (b) studying the effect of substituents on these systems. Accurate oxidation and reduction potentials to within 40 mV (3.9 kJ mol(-1)) of experimental values were found using G3(MP2)-RAD//B3-LYP/6-31G(d) gas-phase energies and PCM solvation calculations at the B3-LYP/6-31G(d) level. For larger systems, an ONIOM method in which G3(MP2)-RAD calculations for the core are combined with lower-cost RMP2/6-311+G(3df,2p) calculations for the full system, was able to approximate G3(MP2)-RAD values (to within 1.6 kJ mol(-1)) at a fraction of the computational cost. The overall ring structure has more effect on the electrode potentials than the inclusion of substituents. Azaphenalene derivatives display the lowest oxidation potentials and least negative reduction potentials and are thus the most promising target to function as antioxidants in biological systems. Piperidine and pyrrolidine derivatives have intermediate oxidation potentials but on average pyrrolidine derivatives display more negative reduction potentials. Isoindoline derivatives show higher oxidation potentials and more negative reduction potentials. Within a ring, the substituents have a relatively small effect with electron donating groups such as amino and hydroxy groups stabilizing the oxidized species and electron withdrawing groups such as carboxy groups stabilizing the reduced species, as expected.     

Deoxygenation of some α-dicarbonyl compounds by tris(diethylamino)phosphine in the presence of fullerene C60

The reactions of such cyclic α-diketones as acenaphthenequinone, aceanthrenequinone, and N-alkylisatins, with hexaethyltriaminophosphine in the presence of the fullerene C(60), lead to the formation of methanofullerene derivatives under mild conditions. This process proceeds via deoxygenation of the dicarbonyl compound by the P(III) derivative and is likely to involve the intermediate formation of α-ketocarbenes. The structure of some methanofullerenes has been confirmed by NMR and XRD. The electrochemical behavior of the methanofullerenes was also investigated.     

Symmetry breaking in cationic and anionic polymethine dyes

The electron density distribution and equilibrium molecular geometry of ionic polymethine dyes containing both the simplest terminal groups and carbo and heterocyclic residues were investigated by ab initio and AM1 methods. It is shown that charge waves and wave of the carbon–carbon bond lengths in the conjugated chain are of solitonic nature. The dimensions of the charge (electron or hole) soliton and geometrical (topological) soliton are practically unsensitive to the chain lengths, while the wave shape depends on the donor/acceptor strength of the terminal groups. If the length of the chromophore exceeds the dimension of the solitons, then the soliton center in the substituted ionic conjugated systems shifted to one of the chain ends, what leads to an appearance of the asymmetrical form. The conditions of this symmetry breaking (crucial number of the vinylene groups in the chain, effective length and donor/acceptor strength of the terminal residues, total charge) was found and was established that no moving of the solitons occurs in the unsubstituted conjugated ions.