Nitrogen Derivatives Of C-60 And C-70 - Interaction Of Fullerenes With Nitrogen In Gas-Phase

Mass spectrometric studies show that contact-arc vaporization of graphite in a partial atmosphere of N2 or NH3 yields nitrogenous products tentatively assigned to species such as C70N2, C59N6, C59N4 and C59N2 involving addition of or substitution by nitrogen along with the species due to C2 and C4 losses. Mass spectrometry and other techniques have been employed to identify products of the nucleophilic addition of aliphatic amines to C60 and C70 in solution phase.

Preparation, Characterization And Properties Of C-60 And C-70 - Spectroscopy, Structure, Anions, Interaction With Electron-Donors And Superconductivity

Preparation and characterization of the fullerenes, C60 and C70, are described in detail, including the design of the generators fabricated locally. The characterization techniques employed are UV-visible, IR, Raman and C-13 NMR spectroscopies, scanning as well as transmission electron microscopy and mass spectrometry. The electron energy level diagram of C60 as well as the one-electron reductions of C60 and C70 leading to various anions are discussed. Electronic absorption spectra of C60- and C60(2-) are reported. Phase transitions from the plastic to the crystalline states of C60 and C70 are examined. Based on a C-13 NMR study in a mixture of nematic liquid crystals, it has been demonstrated that C60 retains its extraordinary symmetry in solution phase as well. Interaction of C60 and C70 with strong electron-donor molecules has been investigated employing cyclic voltammetry. Superconductivity of K(x)C60 has been studied by non-resonant microwave absorption; Na(x)C60 as well as K(c)C70 are shown to be non-superconducting. Doping C60 with iodine does not make it superconducting. Interaction of C60 with SbCl5 and liquid Br2 gives rise to halogenated products.

GAS-PHASE ACETYLATION OF C-60 AND C-70 BY ION/MOLECULE REACTIONS

Gas phase reactions of C-60 and C-70 with the ion system of acetone under chemical ionization conditions have been studied. C-60 and C-70 can react with acetyl and oxonium ions, which come from self-chemical ionization of acetone, to form adduct ions. In addition, C-60 and C-70 can accept protons to produce protonated ions. C-70 is more active in the above reactions than C-60 because of its stronger gas-phase basicity. A sigma-bond between C-60 and an acyl carbon atom can be formed to produce stable acetylated C-60 ions. The above results may be relevant to the acetylation reactions of C-60 in the condensed phase.

Gas-phase Ion-molecular Reactions of C-60 and C-70 with Acetone and Quantum Chemistry Study

Gas-phase ion-molecular reactions of C-60 and C-70 with the ion system of acetone have been studied in this paper. The ions of protoned and acetylized C-60 and C-70 were formed by the reactions of C-60 and C-70 with some ions which existed in the ion system when mass spectrometer worked on chemical ionization conditions. The reactivity of C-70 is greater than that of C-60. Results of quantum chemical calculation for the adduct ions showed a sigma bond between the acyl carbon atom and C-60 may be Formed. These results will provide some valuable informations on the condense-phase acetylization of C-60.

酚酞型聚芳醚砜共聚物与共混物－(PP/BiS-T) PES共聚物和(PPS/PES-C)、(PPO/PES-C)共混物的合成、结构与性能研究

本工作旨在通过共聚、共混技术制备酚酞型聚芳醚砜共聚物(PP/BiS-T) PES和共混物(PPS/PES-C)、PPO/PES-C，以便改善酚酞型聚芳醚砜（PES－C）的加工性能（特别是注射加工性能）和耐溶剂性能。通过研究共聚物和共混物的微观结构，聚集态结构与性能的关系，探索改善酚酞型聚芳醚硕性能的有效途径第一部分：(PP/BiS-T) PES共聚物的合成、结构与性能(PP/BiS-T) PES共聚物是以4，4'二氯二苯砜（DCDPS）、酚酞（PP）和4，4'－二羟基二苯硫醚(BiS-T)为单体，采用固体无水K_2CO_3/NMP/TMSO_2 混合溶剂反应体系合成的。共聚反应规律研究表明：在NMP/TMSO_2混合溶剂中，共聚反应可以顺利进行，避免了交联反应的发生，并成功地合成了高分子量的(PP/BiS-T) PES共聚物。DSC分析结果表明(PP/BiS-T) PES系列属于无定形的均相共聚物体系，每一组成比例对应的共聚物只具有一个玻璃化转变温度。且随组成比例的改变呈线性变化，TBA分析结果与DSC基本一致，并证实了(PP/BiS-T) PES属于均相共聚物体系，而不是均聚物的共混物。TG分析表明：共聚物具有良好的耐热氧化稳定性BiS-T链节在分子链中起到了提高自身抗氧性的作用。1R光谱对共聚物的结构进行表征。~(13)C-NMR分析确认共聚物多属于无规共聚物。动态力学试验表明共聚物(PP/BiS-T) PES以及PES－C，在－100 ℃附近和0－100 ℃，存在着次级松驰与转变，并发现水分子的存在对这种转变（次级松驰）有一定的影响。共聚物的熔融流动性试验和溶解性试验表明共聚物(PP/BiS-T) PES具有稍好于PES－C的熔融流动性；溶解性与PES－C类似。力学试验说明共聚物属于强而硬类型的聚合物。第二部分：PPS/PES－C共混物的制备、聚集态结构与性能PPS/PES－C共混物是以联苯/二苯硕混合物为溶剂，采用溶液沉析方法制备的，DSC、WAXD，SEM和1R分析手段对共混物的聚集态结构和微观结构进行了表征。DSC分析认为共混物属于多相体系，PPS的结晶性随着PES－C含量增加而降低。DSC和SEM观察结果表明：相转变发生在PPS占40％左右。PPS占25％时，DSC曲线呈现出界面相玻璃化转变温度。共混物具有良好的耐热氧化稳定性和耐热分解稳定性。微晶大小计算结果：PES－C存在导致了PPS微晶大小降低。WAXD曲线表明PPS占50％，共混物中的PPS具有较好的结晶性。SEM观察发现：随着PES－C含量增加，PES－C由分散相（PES－C50％）变为连续相（PES－C70％）。PPS占50％或低于50％时，共混物体系不仅发生了微观相分离，而且发生了宏观相分离。M.I.指数表明共混物中PPS为连续相时，共混物具有良好的熔融流动性。溶解性试验结果：共混物具有较好的耐溶剂性。第三部分：PPO/PES－C共混物的合成、结构与性能 PPO/PES－C共混物系用溶液－涂膜法，以氯彷为溶剂制备的。讨论了由同一共混物溶液浓度下制备的共混物的互溶性随组成的改变而变化。DSC分析结果：PPO/PES－C属于部分相溶性体系。利用Fox方程推导式计算结果表明PPO在富PES－C相中具有良好的分散性；而PES－C在富PPO相中的分散性较差。共混物(PPO/PES－C)试样经丙酮浸泡后，PPO（>50％）发生了溶剂诱导结晶现象，同时丙酮促使共混物发生完全相分离。结晶溶化热显示共混物中少量的PES－C存在有利于PPO的溶剂诱导结晶。TG分析表明共混物具有良好的耐热分解稳定性和耐热氧化分解稳定性。偏光显微镜下观察到PPO球晶的存在。SEM和FT－1R分别对共混物的形态结构和微观结构进行了表征。WAXD试验证实了丙酮处理的(PPO/PES－C)（70/30），（90/10）共混物中PPO的结晶性。溶解性试验表明：PPO掺入有助于 PES－C的耐溶剂性提高。

Formation of heterocyclic C-60 derivative by gas-phase ion/molecule reaction

Ion/molecule reactions of C-60 with vinyl acetate under chemical ionization conditions have been studied here. Compared with C2H3O+ from acetone, C2H3O+ from vinyl acetate undergoes the reactions more easily, a new heterocycle between C-60 and the studied ion is formed The generation of two sigma-bonds and little angle tensile force of pentatomic ring make it more stable.

C-118 from fullerenols: Formation, structure and intermolecular nC(2) transfer reactions in mass spectrometry

In fast atom bombardment, two fullerenols C-60(OH)(x) (x=13-15) and C-60(OH)(x) (x-24-26) gave rise to a group of ions centered at C-118 with intervals of 24 mass units in the high mass region. In contrast, no such ions appeared in the mass spectra of pure C-60, C-70 and other fullerene derivatives such as C-60(C6H5)(10), under the same conditions. It is proposed that the pinacol rearrangement of C-60(OH)(2), resulting from partial rupture of the polyhydroxy molecules, produces C-59 with two carbon atoms bearing an unpaired electron, and that dimerization of this reactive intermediate is responsible for the formation of the predominant product C-118. An intermolecular nC(2) transfer process is used to explain the symmetrical abundance distribution of these product ions in the spectra of fullerenols.

Synthesis and Photodynamic Effect of New Highly Photostable Decacationically Armed [60]- and [70]Fullerene Decaiodide Monoadducts To Target Pathogenic Bacteria and Cancer Cells

Novel water-soluble decacationically armed C-60 and C-70 decaiodide monoadducts, C-60- and C-70[>M(C3N6+C3)(2)], were synthesized, characterized, and applied as photosensitizers and potential nano-PDT agents against pathogenic bacteria and cancer cells. A high number of cationic charges per fullerene cage and H-bonding moieties were designed for rapid binding to the anionic residues displayed on the outer parts of bacterial cell walls. In the presence of a high number of electron-donating iodide anions as parts of quaternary ammonium salts in the arm region, we found that C-70[>M(C3N6+C3)(2)] produced more HO center dot than C-60[>M(C3N6+C3)(2)], in addition to O-1(2). This finding offers an explanation of the preferential killing of Gram-positive and Gram-negative bacteria by C-60[>M(C3N6+C3)(2)] and C-70[>M(C3N6+C3)(2)], respectively. The hypothesis is that O-1(2) can diffuse more easily into porous cell walls of Gram-positive bacteria to reach sensitive sites, while the less permeable Gram-negative bacterial cell wall needs the more reactive HO center dot to cause real damage.

Copper nanoparticles on graphene support: An efficient photocatalyst for coupling of nitroaromatics in visible light

Copper is a low-cost plasmonic metal. Efficient photocatalysts of copper nanoparticles on graphene support are successfully developed for controllably catalyzing the coupling reactions of aromatic nitro compounds to the corresponding azoxy or azo compounds under visible-light irradiation. The coupling of nitrobenzene produces azoxybenzene with a yield of 90 % at 60 °C, but azobenzene with a yield of 96 % at 90 °C. When irradiated with natural sunlight (mean light intensity of 0.044 W cm−2) at about 35 °C, 70 % of the nitrobenzene is converted and 57 % of the product is azobenzene. The electrons of the copper nanoparticles gain the energy of the incident light through a localized surface plasmon resonance effect and photoexcitation of the bound electrons. The excited energetic electrons at the surface of the copper nanoparticles facilitate the cleavage of the NO bonds in the aromatic nitro compounds. Hence, the catalyzed coupling reaction can proceed under light irradiation and moderate conditions. This study provides a green photocatalytic route for the production of azo compounds and highlights a potential application for graphene.

Temperature dependent vibrational lifetimes in supercritical fluids near the critical point

Vibrational relaxation measurements on the CO asymmetric stretching mode (similar to 1980 cm(-1)) of tungsten hexacarbonyl (W(CO)(6)) as a function of temperature at constant density in several supercritical solvents in the vicinity of the critical point are presented. In supercritical ethane, at the critical density, there is a region above the critical temperature (Tc) in which the lifetime increases with increasing temperature. When the temperature is raised sufficiently (similar to T-c + 70 degrees C), the lifetime decreases with further increase in temperature. A recent hydrodynamic/thermodynamic theory of vibrational relaxation in supercritical fluids reproduces this behavior semiquantitatively. The temperature dependent data for fixed densities somewhat above and below the critical density is in better agreement with the theory. In fluoroform solvent at the critical density, the vibrational lifetime also initially increases with increasing temperature. However, in supercritical CO2 at the critical density, the temperature dependent vibrational lifetime decreases approximately linearly with temperature beginning almost immediately above T-c. The theory does not reproduce this behavior. A comparison between the absolute lifetimes in the three solvents and the temperature trends is made.

Pressure-Induced transitions in amorphous TlxSe100-x alloys

The electrical resistivity of bulk semiconducting amorphous TlxSe100-x alloys with 0 ≤ x ≤ 25 has been investigated up to a pressure of 14 GPa and down to liquidnitrogen temperature by use of a Bridgman anvil device. All the glasses undergo a discontinuous pressure-induced semiconducting-to-metal transition. X-ray diffraction studies on the pressure-recovered samples show that the high-pressure phase is the crystalline phase. The pressure-induced crystalline products are identified to be a mixture of Se having a hexagonal structure with a = 4·37 Aring and c = 4·95 Aring and TlSe having a tetragonal structure with a = 8·0 Aring and c = 7·0 Aring

Evidence for extensive population structure in the white-spotted eagle ray within the Indo-Pacific inferred from mitochondrial gene sequences

The white-spotted eagle ray Aetobatus narinari is a species complex that occurs circumglobally throughout warm-temperate waters. Aetobatus narinari is semi-pelagic and large (up to 300 cm disc width), suggesting high dispersal capabilities and gene flow on a wide spatial scale. Sequence data from two mitochondrial genes, cytochrome b (cytb) and NADH dehydrogenase subunit 4 (ND4), were used to determine the genetic variability within and among 18 sampling locations in the central Indo-Pacific biogeographical region. Populations in the Indo-Pacific were highly genetically structured with c. 70% of the total genetic variation found among three geographical regions (East China Sea, Southeast Asia and Australia). FST was 0.64 for cytb and 0.53 for ND4, with φST values being even larger, that is, 0.78 for cytb and 0.65 for ND4. This high-level genetic partitioning provides strong evidence against extensive gene flow in A. narinari. The degree of genetic population structuring in the Indo-Pacific was similar to that found on a global scale. Global FST was 0.63 for cytb and 0.57 for ND4, and global φST values were 0.94 for cytb and 0.82 for ND4. This suggests that the A. narinari complex may be more speciose than the two or three species proposed to date. Further sampling and genetic analyses are likely to uncover the ‘evolutionarily significant’ and ‘management’ units that are critical to determine the susceptibilities of individual populations to regional fishing pressures and to provide advice on management options. Network analyses showed a close genetic relationship between haplotypes from the central Indo-Pacific and South Africa, providing support for a proposed dispersal pathway from the possible centre of origin of the A. narinari species complex in the Indo-Pacific into the Atlantic Ocean.