(Cyclopentadienyl)chromiumtricarbonyl dimers as a source of metal-centered free-radicals to form stable η-bonded spin-adducts with fullerenes

Spin-adducts (I, IIb-c) of C₆₀ and C₇₀ with metal-centered free radicals CpCr(CO)₃ (I, IIa) have been generated in toluene via interaction between fullerenes and the weakly metal-metal bonded dimeric complexes [CpCr(CO)₃]₂ (Cp = η⁵-C₅H₅ (I); Cp = η⁵-C₅Me₅ (II)). Their structures have been investigated using ESR spectroscopy and DFT-PBE calculations and η²-bonding to the CC bond between two hexagons in C₆₀ has been established. Calculations have been extended to investigate the nature of the intermediate η²-coordinated toluene chromium complexes (I, IId).     

Synthesis of [60]fullerene-based α-amino acid derivatives

N-(2-methyl-5,6,7,8-tetrahydro[60]fullero[1,2-g]quinazolin-4-yl)-α-amino acid derivatives were obtained by Diels-Alder addition of adequately substituted pyrimidine ortho-quinodimethanes to C₆₀. One of the new compounds is a l-lysine derivative were both the amino and the carboxyl groups are free; this compound is suitable to be incorporated in peptides.     

Comparison studies of fullerenes C72, C74, C76 and C78 by tight-binding Monte Carlo and quantum chemical methods

From C₇₂ to C₇₈, the top 20 low-energy isomers screened out from all isomers of each fullerene are optimized and computed by tight-binding Monte Carlo (TBMC), semi-empirical PM3, and ab initio B3LYP/6-31G*//HF/3-21G methods. The comparison results show that the TBMC method can efficiently optimize the structures and correctly predicate the low energy isomers. The relative energies computed by TBMC are in good agreement with the high-lever B3LYP calculation results. Our TBMC and B3LYP results show that the most energetically favorable structure of C₇₂ is not an isomer satisfying the isolated pentagon rule (IPR), which is different with the result by PM3. The symmetry of the most stable IPR isomer tends to low as the fullerene becomes large and several non-isolated-pentagon structures are found to have low symmetries and low energies close to the most stable isomer.     

Isolation and characterisation of both the first fluoroxyfluorofullerene C60F17OF and oxahomofluorofullerenol C60F17O.OH

The first fluoroxyfluorofullerene C₆₀F₁₇OF (A) has been isolated from the fluorination of [60]fullerene with a mixture of MnF₃ and K₂NiF₆ at 480 °C. This compound has a shorter HPLC retention time than the isomeric fluorofullerene ethers (oxahomofullerenes) and is less stable towards EI mass spectrometry. It fragments by losing OF as a single entity and shows no formation of C₆₀O as a fragment ion. By contrast, the ethers fragment by first losing a number of F atoms and then CO, and ultimately show also the presence of C₆₀O, whilst epoxides lose CO as a main fragmentation step and do not give C₆₀O. The first oxahomofluorofullerenol C₆₀F₁₇O.OH (B) has been isolated from the UV-irradiation of a toluene solution of C₆₀F₁₈ in air during 65 h and readily eliminates HF due to adjacent F and OH groups during EI mass spectrometry. The structures of both the compounds have been deduced from 1D and 2D NMR spectroscopy. Just as oxygen inserts into FCCF bonds of C₆₀F₁₈ to give ethers, so insertion into a CF bond gives A. The oxahomofluorofullerenol B is produced by S_N2′ substitution of F by OH, followed by oxygen insertion into a 6:5-bond (αβ to the OH group) giving a motif not seen previously in fluorofullerenes.     

Structure and photoelectrochemical properties of nanostructured SnO2 electrodes deposited electrophoretically with the composite clusters of porphyrin-modified gold nanoparticle with a long spacer and fullerene

Structure and photoelectrochemical properties of nanostructured SnO₂ electrodes deposited electrophoretically with the composite clusters of porphyrin-modified gold nanoparticle with a long, flexible spacer and C₆₀ molecules have been examined to obtain basic information on the development of organic solar cells with a high performance. The photoelectrochemical system with the long, flexible spacer between the porphyrin and the gold nanoparticle in the porphyrin-modified gold nanoparticle exhibited comparable external quantum yield in the UV-vis regions relative to porphyrin-modified gold nanoparticle with a relatively short spacer—C₆₀ composite reference system. These results demonstrate that a suitable spacer to incorporate C₆₀ molecules efficiently between the porphyrins in porphyrin-modified gold nanoparticles is a prerequisite for improving the performance of porphyrin and fullerene-based organic solar cells.     

Energetic analysis of 24 C20 isomers

Twenty-four individual geometric structures of the 20-carbon system are investigated using hybrid Hartree–Fock/density functional theory (DFT-B3LYP) in combination with the 6-31G and 6-311G* basis sets. These computations are carried out in order to evaluate the relative energies of the various C₂₀ isomers utilizing both geometry optimization and single-point energy calculations. The relative energies of the three most widely studied C₂₀ isomers (ring, bowl, and cage) are compared to the energies of other cyclic, bowl-like, and miscellaneous isomers. Although the ring and the bowl isomers are predicted to be the two most stable species, we have identified three to four additional cyclic structures that are predicted to be energetically competitive with the fullerene structure.     

电弧法和成笼内含铒的金属富勒烯Er@ C2n

Endohedral metallofullerenes Er@ C2n were synthesized using the carbonarc discharge method of activating the Er2O3- containing graphite anode in situ and bask-burning technique. A toluene soxhlet and pyridine high-temperature high-pressure extraction technique were employed for the effective extraction of Er@ C2n. The formation of Er@ C2n was confirmed by LD-TOF and DEIMS characterization.     

Anhydride-functionalized fullerene: a versatile precursor for fullerene-based materials

Soluble phthalic anhydride-functionalized fullerene was generated via simple pyrolysis of the corresponding di-t-butyl phthalate precursor at 200 °C for 120 min. This non-chemical method for generating electrophilic fullerene may be advantageous for the preparation of various fullerene-containing materials. The utility of the resulting fullerene anhydride was demonstrated by solution coupling reaction with PEG-amine, surface reaction with amine-functionalized glass, and hydrolysis reaction to form amphiphilic fullerene.     

Synthesis, crystal structure and photoconductivity of new molecular complex of C60 with tetrabenzo(1,2-bis[4H-thiopyran-4-ylidene]ethene): Bz4BTPE C60

A new molecular complex of C₆₀ with tetrabenzo(1,2-bis[4H-thiopyran-4-ylidene]ethene), Bz₄BTPE C₆₀ (1) has been obtained. The complex has a layered structure in which closely packed hexagonal layers of C₆₀ alternate with the layers composed of Bz₄BTPE molecules. The complex has a neutral ground state according to UV-vis-NIR spectrum. It has been found that single crystals of 1 show low ‘dark’ conductivity of σ∼10⁻¹⁰ (Ω cm)⁻¹. A 10² increase in photocurrent has been observed upon illuminating the crystal with white light. Photoconductivity of 1 is sensitive to magnetic field with B₀<1 T and increases up to 5% in magnetic field. The photoconductivity spectra of the complex indicate that free charge carriers are generated in the UV-visible range mainly by the Bz₄BTPE excitation (the peaks at 622, 562, 472 and 348 nm) with a possible contribution of charge transfer excitations between neighboring C₆₀ molecules (the peak at 472 nm).     

碳笼烯(C_(60)/C_(70))载体钕系催化异戊二烯聚合

较系统地研究了Ｎｄ（ｎａｐｈ）３ Ｃ６０Ｘ Ａｌ（ｉ Ｂｕ）３碳笼烯钕系催化异戊二烯配位聚合的反应规律，并测定了聚合物分子量、分子量分布和微观结构．碳笼烯钕系为一均相体系．Ａｌ／Ｎｄ及Ｃｌ／Ｎｄ摩尔比对催化体系的活性、聚合物分子量都有较大的影响，活性中心的形成有很好的时间和温度的稳定性．ＰＩｐ的特性粘数［η］在２左右，分子量分布ＭＷ／Ｍｎ在３左右，均小于传统钕催化体系．ＰＩｐ的顺式含量大于９７％．