Semiempirical molecular dynamics studies of C60/C70 fullerene oxides: C60O, C60O2 and C70O

The spectral analysis indicates that all isomers of C₆₀O, C₇₀O and C₆₀O₂ have an epoxide-like structure (an oxygen atom bridging across a C–C bond). According to the geometrical structure analysis, there are two isomers of fullerene monoxide C₆₀O (the 5,6 bond and the 6,6 bond), eight isomers of fullerene monoxide C₇₀O and eight isomers of fullerene dioxide C₆₀O₂. In order to simulate the real reaction conditions at 300 K, the calculation of the different isomers of C₆₀O, C₆₀O₂ and C₇₀O fullerene oxides was carried out using the semiempirical molecular dynamics method with two different approaches: (a) consideration of the geometries and thermodynamic stabilities, and (b) consideration of the ozonolysis mechanism. According to the semiempirical molecular dynamic calculation analysis, the probable product of this ozonolysis reaction is C₆₀O with oxygen bridging over the 6–6 bond (C_2v). The most probable product in this reaction contains oxygen bridging across in the upper part of C₇₀ (6–6 bond in C₇₀O-2 or C₇₀O-4) an epoxide-like structure. C₆₀O₂-1, C₆₀O₂-3 and C₆₀O₂-5 are the most probable products for the fullerene dioxides. All of these reaction products are consistent with the experimental results. It is confirmed that the calculation results with the semiempirical molecular dynamics method are close to the experimental work. The semiempirical molecular dynamics method can offer both the reaction temperature effect by molecular dynamics and electronic structure, dipole moment by quantum chemistry calculation.     

The hydrogenolysis of C60 and C70

Temperature-programmed reaction (TPR) of C₆₀ and C₇₀ with H₂ was carried out on nickel in order to investigate the thermal stability of the fullerenes in the catalytic hydrogenation. The TPR profiles showed two methanation peaks and the corresponding weight decrease above 420°C, indicating the hydrogenolysis to CH₄. This revised version was published online in June 2006 with corrections to the Cover Date.     

Catalytic hydrogenation of C60 on transition metals

The catalytic hydrogenation of C₆₀ on Ru, Rh and Ir produced C₆₀H₁₈ mainly, while Pd, Pt, Co and Ni catalysts gave C₆₀H₃₆ principally. Very little activity was observed on Au and Fe. The higher hydrogenated fullerene obtained on Pd, Pt, Co and Ni was ascribed to the smaller % d-character of the metallic bond, on which the fullerene and hydrogen may more strongly be adsorbed. This revised version was published online in August 2006 with corrections to the Cover Date.     

氯化锌催化下C60与枞酸的反应

拟利用枞酸分子中的非同环共轭二烯在氯化锌作用下异构化成具有同环共轭二烯的海松酸结构, 再与C₆₀进行Diels-Alder加成反应, 预测可以得到Diels-Alder加成产物. C₆₀、枞酸及氯化锌在邻二氯苯溶剂中, 在氮气保护下于175～180 ℃反应8 h, 将反应物洗涤后进行硅胶柱层析分离, 采用FT-IR, ¹³C NMR, ¹H NMR和MALDI-TOF-MS等分析方法对反应主要产物进行结构测定, 却意外发现得到C₆₀与枞酸的加成过程中发生了脱羧脱氢反应且产物含有芳环的化学结构.     

Theoretical investigation on the two-photon absorption of C60

We present a theoretical study on the two-photon absorption (TPA) properties of C₆₀. On the basis of the equilibrium geometry optimized by B3LYP/6-31G method, we employ the ZINDO method combined SOS formula to investigate the second hyperpolarizability and TPA cross section of C₆₀. The calculated result of the real part of the second hyperpolarizability of C₆₀ is in good agreement with the previous calculation and the experimental observation. In the 400–1000 nm range of TPA wavelength, we calculated TPA cross sections corresponding to all two photon allowed states. As a result, we find that there is only a TPA cross section maximum—995.7×10⁻⁵⁰ cm⁴ s/photon at 518 nm. Another interesting phenomenon is that C₆₀ possesses the distinct TPA process in contrast to other conjugated molecules in terms of three-state approximation. This paper provides a theoretical basis of further studying TPA properties of C₆₀.     

C60及其衍生物非线性光学材料的研究进展

介绍了非线性光学性质的原理以及目前研究的具有这种特殊性质的功能材料的结构特点和应用. C₆₀具有的特殊结构, 使其在众多领域成为了研究的重点. C₆₀本身就具有良好的非线性光学性能, 对其修饰得到的各种衍生物更体现优良的性质, 尤其是目前人们大量研究的富勒烯高分子化功能材料具有非常快速的非线性响应时间. 因此重点介绍了C₆₀及其衍生物的结构、非线性光学原理、性质和国内外最新的研究状况.     

C60睛胺类衍生物的合成及三阶非线性光学性质

Ｃ６０的三阶非线性光学性质的研究是近年来富勒烯物理化学性质的研究热点之一［１］．研究显示,尽管Ｃ６０具有三维共轭的π电子体系,其本身并不具有大的三阶非线性系数［２,３］．但由于Ｃ６０分子具有较低的三重简并ＬＵＭＯ能级,显示出较强的电负性,能够与适当的?..     

Complexes of a bio-molecule and a C60 cage

C₆₀ is the most important fullerene cage and glycine is the simplest representative of a backbone unit of a protein. In this paper, the structures and the energies of glycine–C₆₀ complexes were calculated at the B3LYP/6-31G(d) level DFT. It was found that the binding of glycine to C₆₀ generated a slightly unstable complex via its amino nitrogen, a moderately unstable complex via its hydroxyl oxygen, and a very unstable complex via its carbonyl oxygen. This indicates that fullerene cages might be unable to form stable bindings to proteins via their amino nitrogen, hydroxyl oxygen and carbonyl oxygen active sites.     

Co-aggregation of fullerene C60 and thiophene in the non-aromatic solvent cyclohexene

Co-aggregation of fullerene C₆₀ and thiophene has been studied calorimetrically in cyclohexene at 25 °C. The total aggregation heat is found to depend on initial concentration of thiophene and fall between −1.9 and −5.8 kJ mol⁻¹. The corresponding thiophene/fullerene molar ratio (“co-aggregation number”) ranges from 7 to 12. The data are rationalized by formation of heteromolecular nanoaggregates with intermolecular contacts of both fullerene–thiophene and fullerene–fullerene types. A physical model describing interaction between fullerenes and π-donors in solution is substantiated and used to explain heterogeneity of composites containing fullerenes.     

C60的加成反应

富勒烯化学是以全碳分子球烯为母体的新兴有机化学领域, 在材料、医学及立体化学合成方法等方面具有广泛的应用和发展前景。本文综述了C₆₀的加成反应, 较全面地展示了富勒烯的化学性质。     

富勒烯[C60]杂环化合物的合成进展

综述了近年来通过环加成反应合成三元、五元、六元和七元杂环C₆₀衍生物的进展.     

The intermolecular potential function of Smith–Thakkar type for C60

The intermolecular potential function of Smith–Thakkar type for C₆₀ has been proposed, and its expression is as follows

The unit of u(r) is J/mol, r is the distance between two C₆₀ molecules center and the unit is nm. Some properties of C₆₀ in the gas and crystal have been studied using the interaction potential of Smith–Thakkar type, such as stability of C₆₀ crystals, virial coefficient and lattice dynamics.     

甲基紫精对三乙胺与C60反应的催化作用

采用ESR技术对甲基紫精(MV2 )在三乙胺与C60的电子转移反应中的催化作用进行了研究.反应体系无MV2 存在时,三乙胺与C60并不发生电子转移反应,得不到电荷的分离态;在MV2 存在的条件下,由三乙胺向C60分子的电子转移得以实现,并检测到活泼中间体MV ·及电荷分离态C-·60,MV2 　实质上起到催化剂的作用.     

Easily characterized systems of C60 grafted on SiO2

Fullerenes grafted on silica with cleavable anchors give materials that can be easily characterized after thermal/chemical treatment or use as catalysts. Transesterification of an ester linkage leads to detachment of the fullerene moiety from the silica and permits study with standard spectroscopic methods. In particular, UV-vis spectroscopy was proved to be a valuable tool permitting structure analysis and quantitative determination at the same time.     

Higher trifluoromethylated derivatives of C60, C60(CF3)16 and C60(CF3)18: Synthesis, structure, and theoretical study

Three isomers of C₆₀(CF₃)₁₆ and one isomer of C₆₀(CF₃)₁₈ have been isolated by HPLC from a mixture prepared by trifluoromethylation of C₆₀ with CF₃I in a glass ampoule at 380-400 °C. The molecular structures of the four new compounds have been determined by means of X-ray single crystal diffraction and discussed in terms of mechanistic pathways of their formation and relative stability according to the DFT calculations.     

He+C60↔(He@C60)的反应势垒研究

The reaction barriers of (He+C60(He＠60)) have been calculated by the quantum-chemical method EHMO/ASED in the following four paths: (1) penetrate through the pentagon on the C60 cage; (2) penetrate through the hexagon on the C60 cage,(3) penetrate through the short bond; (4) penetrate through the long bond. Corresponding to each path, there are two choices: (a) while He penetrate C60 cage, the distances of the C’s which are the most adjacent to He are changed with a planar extension and a concerned window is formed; (b) while He penetrate C60 cage, the distances of the C’s which are the most adjacent to He are changed with a spherical extension and a concerned window is formed. The results are given in Figs. 1-2 and Tables 1-2. It is shown that the reaction through path(4) with choice (a) has the least reaction barrier, being optimum. At that case, a window of 9-membered ring is formed. Because the window extension of C6H6 is more free than that of C60, the barrier of He penetrating through C6H6 will be lower than that of He penetrating through C60.     

内嵌复合物X@C60中相互作用的变化规律与键本质

系统地研究了内嵌复合物Ｘ＠Ｃ６０（Ｘ＝第ＩＡ簇或第ＶＩＩＡ族元素）形成过程的能量变化,以及其中笼环境下Ｘ与Ｃ６０间相互作用的变化特征与键本质。结果表明：（１）Ｃ６０笼环境力场具有球对称性;（２）各种分解与总相互作用与内嵌原子的原子序数或原子半径呈现出规则的递变规律;（３）除Ｉ外,其余元素原子与Ｃ６０间的作用对各自复合物的稳定性都有正效应的较大贡献;（４）Ｘ在Ｃ６０笼环境中居心或偏心的稳定位置是各种     

C60微电极伏安法研究

The microdisk electrode voltammetric behaviors of C_(60) are reported in this communication. This was accomplished by use of a mixed solvent system as Acetonotrile:Xylene=1:4 and a supporting electrolyte as 0.1 mol·L~(-1) Bu_4NPF_6. Au, Pt and Hg (Pt) were used as working electrode. In this new conditions, the successive six step reduction of C60 were obtained at below 15 ℃. It was found that the former five steps are all the single electron reversible reduction, but behaviors of the sixth steps are like EC' processes. Several electrochemical data were determined.     

One-pot three-component reaction of C60, amino acid and fluorinated benzaldehyde to C60-pyrrolidine derivatives

A series of fluorinated 2,5-disubstituted C₆₀-pyrrolidine derivatives were synthesized via one-pot three-component reaction of C₆₀, amino acid and fluorinated benzaldehyde under reflux in toluene or microwave irradiation. The cis- and trans-isomers could be isolated by chromatography and fully confirmed by ¹H NMR.