Complexes of C60 fullerene with simple donor molecules: Theoretical study

The complex formation between fullerene C60 and simple donor molecules such as dimethyl ether, dimethylamine, dimethylsulfide, furan, pyrrole, and thiophene has been studied applying the hybrid MP2/6‐31G(d′):PM3 ONIOM approach for geometry optimization. Local implementation of Møller–Plesset perturbation theory in combination with 6‐31G(d) and 6‐311G(d,p) basis sets was used for binding energies estimation of fullerene complexes. Two factors were found to contribute most to the complex stability: the polarizability and molecular volume of donor molecule. As follows from positive stabilization energies at the Hartree–Fock level, the stabilization of fullerene complexes is entirely due to dispersion interactions in accordance with available experimental data. The calculations show that for donors of similar molecular volume the binding energy of molecular complex increases with polarizability of donor molecules. Similarly, for such complexes the partial charges on molecules increase with decreasing of ionization potentials of donor molecules. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002     

Theoretical study of structure and stability of fullerene derivative: C50O

A total of eight possible isomers of C₅₀O, an oxide of fullerene C₅₀ (D_5h), have been investigated by B3LYP/3‐21G calculations. The isomer, which has an annulene‐like structure with oxygen bridging across a [5,6] type C? C bond at the site between the pole and the equatorial belt, is found being the ground state of C₅₀O. Four isomers are relatively more stable and the energy differences between them are not large. This result indicates that more than one C₅₀O isomer will coexist once C₅₀O is synthesized. The relative stabilities of the C₅₀O isomers may be determined mainly by the strain release and by the formation of the cyclic phenylene substructure at the equatorial belt of the cage. The calculated nucleus independent chemical shifts (NICS) of the C₅₀O isomers will be useful because from them one can expect outstanding NMR properties that can lead to their identification and characterization. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

Theoretical studies of C60/C70 fullerene derivatives: C60O and C70O

A semiempirical (AM1) calculation on the structures and stabilities of isomers of the fullerene derivatives C₆₀O and C₇₀O is carried out. The ozonolysis reaction mechanism and the thermodynamics of the compounds are studied. The two isomers of C₆₀O (56 bond and 66 bond) formed by an oxygen atom bridging across a C-C bond have an epoxide-like or an annulene-like structure. According to the ozonolysis reaction mechanism and kinetic factor analysis, the possible products of this ozonolysis reaction are C₆₀O with oxygen bridging over the 66 bond (C_2v) as an epoxide-like isomer and that with oxygen bridging over the 56 bond (C_s) as an annulene-like isomer. Further, the sixteen isomers of C₇₀O (both epoxide-like and annulene-like structures) have been studied with respect to the same reaction mechanism. The most possible product in this ozonolysis reaction contains oxygen bridging across in the upper part (66 bond in C₇₀O-2 or C₇₀O-4) as an epoxide-like structure. The other possible product is C₇₀O-8 (annulene-like structure), in which oxygen bridges across an broken equatorial CC bond in C₇₀ (D_5h). The vibrational frequency analysis and the electronic structure of the selected C₆₀O and C₇₀O isomers are generated for experimental characterisation. The experimental results indicate that C₆₀O and C₇₀O may decompose into the odd number fullerenes C₅₉ and C₆₉. We therefore studied the structures of C₅₉ and C₆₉ also.     

Theoretical investigation of an energetic fullerene derivative

A self‐consistent estimation method for the thermochemical properties of N‐methyl‐3‐(2′,4′,6′‐trinitrobenzene)‐fulleropyrrolidine (MTNBFP) is presented. This method is based on enthalpy of formation (Δ_fH) and enthalpy of combustion obtained from BLYP/DNP calculations of the total energies and frequencies for MTNBFP. The enthalpy of formation was calculated by an optimized set of isodesmic reactions given the available experimental Δ_fH of relative compounds. MTNBFP has a high enthalpy of formation, 2782.2 kJ/mol. Detonation velocity and detonation pressure were also presented in terms of Kamlet and Jacobs equations. Drop hammer impact sensitivity tests and blasting point per 5 s tests indicate MTNBFP may be a potential candidate primary explosive. To understand the test results well, we proposed a series of chemical reaction mechanisms and interpreted the relationship between impact sensitivity and electronic structures from the viewpoint of nitro group charge, electrostatic potential, and vibrational modes. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010     

Influence of fullerene C60 on the structure and mechanical properties of polyethylene

Influence of fullerene C₆₀ on the structure and mechanical properties of low-density polyethylene samples cast from a melt and a solution was studied.     

Synthesis and properties of water-soluble derivatives of fullerene C60

Procedures for synthesized of water-soluble forms of fullerene C₆₀ and its derivatives were developed.     

两种C~6~0双炔衍生物的结构、光谱和二阶非线性光学性质的 理论研究

用INDO/2和INDO/SCI方法,计算了C~6~0C(C=CH)~2基态电子结构和电子光谱,所得结果与实验结果基本一致.在此基础上,设计了C60(C=CH)~2,并用同样方法计算了电子结构和光谱.在正确的电子光谱基础上,用ZINDO-SOS方法计算了2个分子的二阶非线性光学系数β~i~j~k和β~μ,并对其结果进行了分析和讨论.结论是,乙炔基与C~6~0(C=CH)~2有更大的非线性光学系数,是有希望的非线性光学备选材料分子。     

Hyperpolarizability of the C60 fullerene cluster

Motivated by a discrepancy of five orders of magnitude between three different hyperpolarizability measurements on the C₆₀ fullerene, we calculated the optical response of this cluster using a tight-binding Hamiltonian and compared the results to those for a benzene molecule. Our Hamiltonian reproduces the linear polarizability and hyperpolarizability of benzene reasonably well. For C₆₀, our calculations of the bare polarizability agree only with two of the optical response measurements and indicate that the corresponding linear and nonlinear response of C₆₀ is much larger than that of C₆H₆. We find that screening effects decrease this difference strongly, and also reduce the calculated hyperpolarizability of C₆₀ to a value which is two orders of magnitude below the favored measurements.     

Aqueous dispersions of C60 fullerene by use of amphiphilic block copolymers: preparation and nonlinear optical properties

The dispersion of the otherwise insoluble C60 fullerene in water is discussed. Amphiphilic block copolymers, namely, polystyrene-b-polyethylene oxide (PS-PEO), were found to be able to disperse C60 in aqueous solutions, where the polymer forms micelles with a hydrophobic PS core. The preparation protocol of the final solutions was found to play a crucial role in the ability of the block copolymer to disperse the C60 molecules. The C60 containing aggregates were studied using optical spectroscopy, light scattering, and scanning electron microscopy. In addition, their optical limiting action and nonlinear optical properties under visible nanosecond laser excitation were studied and compared with that of C60-toluene solutions.     

Adsorption of ascorbic acid on the C60 fullerene

Adsorption of ascorbic acid (AsA) on C60 is investigated using classical molecular mechanics and density functional theory (DFT). Classical annealing was performed to explore the space of molecular configurations of ascorbic acid adsorbed on C60, searching for optimal geometries. From the structure with the smallest total energy, 10 initial configurations were prepared by applying rotations of 90 degrees about three orthogonal axes. Each one of these configurations was optimized using DFT (for both LDA and GGA exchange-correlation functionals), and an estimate of their total and adsorption energies was found. Different configurations have minimal adsorption energies (defined here as the total energy of the adsorbate minus the total energy of the separate molecules) from -0.54 to -0.10 eV, with distinct optimal distances between the AsA and C60 centers of mass. According to a Hirshfeld population analysis, AsA is, in general, an acceptor of electrons from C60. Our results demonstrate the feasibility of noncovalent functionalization of C60 with AsA and provide minimal energy values for the several different configurations investigated. These results should be considered in reactions as a possible way to prevent against the oxidative damage and toxicity of C60. The beneficial effects of using AsA-C60 includes its action when administered together with levodopa, against the neurotoxicity generated by levodopa isolated, which opens new strategies for the Parkinson's disease treatment.     

Solvent Effects on the Solubility of C60 fullerene

The solubility of C₆₀ fullerene in organic liquids is not directly related to any of their physicohemical characteristics, but can be quantitatively described by linear multiparameter equations. The solubility increases with increasing solvent polarizability and decreases with increasing solvent polarity and cohesive energy density. Various types of multiparameter equations proposed in the literature were compared to show that they all are suitable but Koppel-Palm's equation is preferred.     

Electrochemical polymerization of fullerene C60

Cyclic voltammetry data show that fullerene C₆₀ films on the Pt electrode surface in MeCN are electropolymerized to form polymeric C₆₀. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 863–865, April, 1997.     

Toward chiral polyhydroxylated dendrimers. Preparation and chiroptical properties

Four dendrimers (1b-4b) containing chiral vicinal diol-based subunits were prepared from their acetonide-protected precursors (1a-4a). The optical activity of these chiral dendritic structures was successfully modeled using structurally similar, low molecular weight model compounds. Using the [Phi](d) values of the low molecular weight model compounds 5b-7b, we calculated [Phi](d) values for dendrimers 1b-4b that agree to within 4.5% of the observed values. Agreement between the optical activity of the model compounds and that of the dendrimers leads to the conclusion that the conformational equilibria of the dendrimer subunits are not perturbed relative to those of the model compounds.     

Nonlinear optical properties of ferrocene- and porphyrin-[60]fullerene dyads.

A series of novel [60]fullerene-ferrocene and [60]fullerene-porphyrin dyads, in which a fullerene and an electron donating moiety are attached through a flexible triethylene glycol linker are synthesized and their nonlinear optical (NLO) response studied. Specifically, the third-order susceptibility chi(3) of all fullerene derivatives are measured in toluene solutions by the optical Kerr effect (OKE) technique using 532 nm, 35 ps laser pulses and their second hyperpolarizability gamma are determined. All fullerene dyads studied exhibit enhancement of their NLO response compared to pristine fullerenes which has been attributed to the formation of a charge separated state. All experimentally measured hyperpolarizability gamma values are also calculated by the semiempirical methods AM1 and PM3. A good correlation is found between the theoretical and experimental values, suggesting that simple semiempirical methods can be employed for the designing and optimization of the fullerene-containing dyads displaying improved nonlinear responses.     

ESR study of spin-adducts of trimethylaminoboryl radicals with fullerene C60

It was established by ESR that trimethylaminoboryl radicals formed by UV irradiation of BH₃NMe_6w in the presence of di-tert-butyl peroxide in saturated benzene solutions of fullerene C₆₀, add to fullerenes to give C₆₀-BH₂NMe₃ spin-adducts. The latter undergo dimerization with a rate constant ofca. 2.5 · 10⁶ L mol^–1 s^–1. A more prolonged photolysis of excess BH₃NMe₃ in a benzene solution of C₆₀ results in multiple addition of the trimethylaminoboryl radicals to the fullerene to give stable radicals C₆₀[BH₂NMe₃]_n.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 673–675, April, 1994.     

The reaction of fullerene C(60) with 4,6-dimethyl-1,2,3-triazine: formation of an open-cage fullerene derivative.

A thermal reaction of fullerene C(60) with 4,6-dimethyl-1,2,3-triazine (4) in o-dichlorobenzene gave azacyclohexadiene-fused fullerene derivative 5, by the reaction with intermediate azete 11, and then, after flash chromatography over SiO(2), open-cage fullerene derivative 6 having an eight-membered ring orifice on the C(60) cage. Compound 6 is assumed to be formed via addition of diradical intermediate 13 to C(60). Compound 6 underwent a further photochemical reaction with singlet oxygen with the cleavage of one of the double bonds at the rim of the orifice to afford triketone derivative 8 having a 12-membered ring orifice.     

Characteristics of fullerene C60-doped polymers

The results of studying the characteristics of various polymers that possess different structures and are used for various applications after their modification by minor amounts of fullerene C₆₀ are summarized. The character of bonds that arise in fullerene-doped polymer compositions is considered. Mechanical, physicochemical, and physical characteristics of fullerene-containing polymers that show promise for modern technologies are described. The reasons for improving the performance of fullerene-containing polymers are analyzed.     

N－甲基-吡咯烷并[3,4]C60衍生物的结构、电子光谱 和二阶非线性光学性质的 理论研究

利用半经验AM1量子化学方法研究了N－甲基－吡咯烷并[3,4]C60(MPC)及其噻吩取代衍生物(TMPC)的几何结构。电子结构研究表明,MPC及TMPC衍生物的前沿轨道主要由C60部分决定,C60母体与成基团之间存在较强的分子内电荷转移,C60部分是电子受体,而噻吩环部分和吡咯环部分为电子给体。在AM1优化几何构型的基础上,用INDO/SCI方法计算了MPC及TMPC的电子光谱,用完全态求和(SOS)公式计算了其二阶非线性光学性质。结果表明,MPC与TMPC在400nm以上均存在吸收峰,TMPC的这些吸收峰(400nm以上)比MPC的吸收峰强得多,与实验所得结果一致。对于TMPC来说,其二阶非线性光学系数β0值随分子构型不同而有较大的变化,β0值最大可达60×10^-30esu。