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151.
We discuss the high pressure properties of different silicon clathrate structures that we have investigated by means of X-ray diffraction and ab initio calculations. Compressibility, transition pressures or phase transformations are interpreted as a function of the nature of the guest atom intercalation. The compressibility of the clathrate structure is in all cases close to that of silicon diamond whereas transition pressures or the high pressure phases are extremely depending on the nature of the guest atom. We address the implications for obtaining a metallic material as hard as diamond. 相似文献
152.
Beatriz Jurado-Sánchez Evaristo Ballesteros Mercedes Gallego 《Journal of chromatography. A》2009,1216(7):1200-1205
The detection of N-nitrosamines (NAms) in water supplies is an environmental and public health issue because many NAms are classified as probable human carcinogens. Non-aromatic (aliphatic and cyclic) NAms are more toxic than aromatic ones as their maximum admissible concentration is limited in drinking water (20–2000 ng L−1). From that premise, a simple and novel method to discriminate between both fractions of NAms according to their toxicity was proposed. An automatic solid-phase extraction unit containing two sequential sorbent columns was constructed. A sample volume of 25 mL was passed through a C60 fullerene column in which only the aromatic fraction was retained, and the effluent was then passed through a Merck LiChrolut EN column where the non-aromatic fraction was retained. Following elution of the non-aromatic NAms with 150 μL of ethyl acetate–acetonitrile (9:1), 1 μL of the extract was injected into a GC/MS. A comparative study of C60 and C70 fullerenes and nanotubes revealed C60 fullerene to be the best choice to selectively retain the aromatic fraction. The method exhibits a linear range of 15–20,000 ng L−1; limits of detection of 4–15 ng L−1; and an RSD of ∼5%. Recoveries throughout the whole method were between 95% and 102% for six non-aromatic NAms spiked into several types of waters. Our study demonstrates that a simple and fast SPE system (10 min per sample) with a customary GC–MS instrument permits the quantification of these amines in complex matrices with considerable sensitivity and selectivity. 相似文献
153.
Mircea V. Diudea 《Journal of mathematical chemistry》2009,45(2):354-363
Operations on maps are topological-geometrical tools used for transforming a given polyhedral tessellation. Investigation
of fullerene structure often needs information on the original map which transformed into a larger molecular structure. Operations
leading to the previous, smaller structures are called Retro-operations. They appear particularly useful in studies of structure
elucidation or stability of series of fullerenes. The paper presents the first structure affiliation of the well-known C60 fullerene to a family of Leapfrog fullerenes with relatedness being established by map operation. Thus, the tessellation
of C60 is described as an Archimedean, joint Sumanene-hexagon covering, in tetrahedral disposition. The other members of family
show essentially the same covering and predicted good stability. Related Leapfrog fullerenes showing a disjoint Sumanene covering
are also given. 相似文献
154.
Daisuke Sukeguchi Shuichi Nakamura Yasuhiko Hayashi Tetsuo Soga 《Journal of fluorine chemistry》2009,130(3):361-5525
Synthesis and spectroscopic investigation of trifluoroethoxy-coated phthalocyanine-fullerene dyad 2 has been described. While nonfluorinated phthalocyanine-fullerene dyad 1 showed an efficient property of intramolecular photoinduced electron transfer, dyad 2, regardless of its covalently linked dyad system, appears not to show any electronic communication between fullerene and phthalocyanine. This observation is presumably due to the strong electron withdrawing nature of 12 trifluoroethoxy groups; fluorine leads phthalocyanine to become an acceptor whose electronic accepting property is equivalent to that of fullerene. This is a unique example that fluorine can terminate electronic communication in the covalently fullerene-phthalocyanine dyad system. 相似文献
155.
One isomer of C60(i-C3F7)8, three isomers of C60(i-C3F7)6, and the first mixed perfluoroalkylated fullerene, C60(CF3)2(i-C3F7)2, have been isolated by HPLC from a mixture prepared by reaction of C60 with heptafluoroisopropyl iodide in a glass ampoule at 260-290 °C. The molecular structures of the four new compounds have been determined by means of X-ray single crystal diffraction partially also by use of synchrotron radiation. Theoretical calculations at the DFT level of theory have been employed to rationalize the energetics of isomers and of C60-Rf binding. 相似文献
156.
Shengqiang Xiao Andrew C. Stuart Shubin Liu Huaxing Zhou Wei You 《Advanced functional materials》2010,20(4):635-643
Polycyclic aromatics offer great flexibility in tuning the energy levels and bandgaps of resulting conjugated polymers. These features have been exploited in the recent examples of benzo[2,1‐b:3,4‐b']dithiophene ( BDT )‐based polymers for bulk heterojunction (BHJ) photovoltaics (ACS Appl. Mater. Interfaces 2009 , 1, 1613). Taking one step further, a simple oxidative photocyclization is used here to convert the BDT with two pendent thiophene units into an enlarged planar polycyclic aromatic ring— q uadra t hieno n aphthalene ( QTN ). The reduced steric hindrance and more planar structure promotes the intermolecular interaction of QTN‐ based polymers, leading to increased hole mobility in related polymers. As‐synthesized homopolymer ( HMPQTN ) and donor–acceptor polymer ( PQTN ‐ BT ) maintain a low highest occupied molecular orbital (HOMO) energy level, ascribable to the polycyclic aromatic ( QTN ) moiety, which leads to a good open‐circuit voltage in BHJ devices of these polymers blended with PCBM ([6,6]‐phenyl‐C61‐butyric acid methyl ester; HMPQTN : 0.76 V, PQTN ‐ BT : 0.72 V). The donor–acceptor polymer ( PQTN ‐ BT ) has a smaller optical bandgap (1.6 eV) than that of HMPQTN (2.0 eV), which explains its current (5.69 mA cm?2) being slightly higher than that of HMPQTN (5.02 mA cm?2). Overall efficiencies over 2% are achieved for BHJ devices fabricated from either polymer with PCBM as the acceptor. 相似文献
157.
Mototada Kobayashi Nozomu Kimata Satoshi Heguri 《Journal of Physics and Chemistry of Solids》2010,71(4):689-691
The X-ray diffraction (XRD), magnetic susceptibility and electron spin resonance (ESR) measurements have been carried out for NaxC60. The XRD profiles with x<4 can be assigned to a face-centered cubic (fcc) lattice, while those with 4≦x to a hexagonal one. The temperature dependence of magnetic susceptibility χ for NaxC60 using SQUID was fitted to the Curie law, and estimated temperature-independent component χ0. The composition x dependence of the χ0 for NaxC60 shows two maxima at around x=3 and x=10, and minimum at x=6. The absence of Pauli contribution at x=6 was confirmed using ESR. A trace of superconducting transition at 14 K has been found for some NaxC60 specimens with 8<x<9. 相似文献
158.
Takeo Oku Tatsuya Noma Atsushi Suzuki Kenji Kikuchi Shiomi Kikuchi 《Journal of Physics and Chemistry of Solids》2010,71(4):551-5167
Fullerene/porphyrin bulk heterojunction solar cells were fabricated and, the electronic and optical properties were investigated. Effects of exciton-diffusion blocking layer of perylene derivative on the solar cells between active layer and metal layer were also investigated. Optimized structures with the exciton-diffusion blocking layer improved conversion efficiencies. Energy levels of the molecules were calculated and discussed. Nanostructures of the solar cells were investigated by X-ray and electron diffraction, which indicated formation of fullerene/porphyrin mixed crystals. Electronic structures of the molecules were investigated by molecular orbital calculation, and energy levels of the solar cells were discussed. 相似文献
159.
Carbon nanomaterials are receiving an increasingly large interest in a variety of fields, including also nanomedicine. In this area, much attention is devoted to investigating and modeling the behavior of these nanomaterials when they interact with biological fluids and with biological macromolecules, in particular proteins and oligopeptides. The interaction with these molecules is in fact crucial to understand and predict the efficacy of nanomaterials as drug carriers or therapeutic agents as well as their potential toxicity when they occupy the active site of a protein or severely affect the secondary and tertiary structure, or even the local dynamics, thus inhibiting their biological function. In this review, therefore, we describe the most recent work carried out in the last few years to model the interaction between carbon nanomaterials, either pristine or functionalized, and proteins or oligopeptides using classical atomistic methods, mainly molecular dynamics simulations. The attention is focused on 0-dimensional fullerenes, mainly C60, on 1-dimensional carbon nanotubes, mostly the single-walled armchair and some chiral ones, and on 2-dimensional graphene and graphyne, the latter containing also sp hybridized atoms in addition to the sp2 ones common to the other carbon nanomaterials. 相似文献
160.
Can Polymer Solar Cells Open the Path to Sustainable and Efficient Photovoltaic Windows Fabrication?
Varun Vohra 《Chemical record (New York, N.Y.)》2019,19(7):1166-1178
Sunlight is among the most abundant energy sources available on our planet. Finding adequate solutions to properly and efficiently harvest it is of major importance to potentially solve the global energy crisis. Polymer solar cells have been introduced in the late 20th century as low‐cost and easily processed alternative to the state‐of‐the‐art silicon photovoltaics. Their power conversion efficiencies, which were initially rather low, are constantly improving and now reach values close to 15 %. As their optical properties can be easily tuned, designing active layer which absorb homogeneously throughout the visible spectrum is relatively simple. These peculiar characteristics enable the possibility to fabricate visibly transparent solar cells with high color rendering indices which can be employed as photovoltaic windows. After reviewing some of the most successful examples of polymer solar cell‐based transparent photovoltaic window fabrication, I will discuss the possibility to produce these devices in a sustainable and/or eco‐friendly manner while maintaining their performances. 相似文献