Raman Spectroscopy of the Charge Transfer Complex (TTF)x C60 Br8

We report Raman studies on powder samples of the charge transfer complex (TTF)_x C₆₀Br₈ at room temperature. The phonons show considerable softening with respect to the frequencies observed in the Raman spectrum of solid C₆₀ Brg. The strongest mode at 1464 cm^-1 in C₆₀Br₈ is red shifted to a doublet with peaks at 1414 and 1421 cm^-1, implying an average phonon softening Δω of -47 cm^-1. A comparison with the phonon softening of the corresponding A_g(2) mode in alkali-doped C₆₀ (Δω ~ - 36 cm^-1 for A₆C₆₀, A = K, Rb or Cs) suggests that 8 electrons are transferred per C₆₀Br₈ molecule in the charge transfer complex. The mode at 503 cm_--1 in C₆₀Br₈ is shifted upwards, similar to that in A₆ C₆₀ compounds.     

Optical Spectra of C60 Complexes At High Pressures

A new absorption band assigned to C₆₀^- was observed around 1000 nm in the electronic spectra of (BEDT-TTF)₂C₆₀ and (ferrocene)₂C₆₀ at high pressures. The result suggests an increase in the ionicity of the complexes with increasing pressure.     

Spontaneous Decay of Highly-Charged Fullerene Ions C60Z and C58z

Using isotope-resolved, two sector field mass spectrometric techniques we have identified and investigated quantitatively the energetics and kinetics (in particular the kinetic energy release, KER) of the spontaneous decay reactions C_60-2m^z+ → C_60-2m-p(z-1)+ ₊ C_p⁺ with m = 0 or 1, z ranging from 3 to 6 and p = 2 and 4. The obtained KER results are not compatible with the properties expected for a single-step fissioning reaction as described by the liquid drop model. Therefore the present data had to be interpreted by a different fragmentation mechanism. This novel reaction sequence, termed auto charge transfer (ACT) reaction, is initiated by the statistically driven neutral C₂ (or C₄₎ evaporation followed by an electron transfer process from the receding C₂ (or C₄) fragment to the remaining highly-charged fullerene ion thereby leading finally to the two charged reaction products observed in the exit channel of the decay reaction. Moreover, in the case that a C₂⁺ loss from C₆₀z+ is occurring in the first field-free region we have been able to demonstrate that it is possible to observe in the second field-free region a subsequent C₂ evaporation from the C₅₈(z-1)⁺ fragment ion.     

13C and Alkali NMR Studies of Electronic and Structural Properties of Alkali Fullerides

Extensive NMR experiments have been performed both on the ¹³C and the alkali NMR in A_nC₆₀. In the superconducting A₃C₆₀. evidences for uniaxial molecular rotations of the C₆₀ and for a low T structural anomaly will be given. The linear chain structure of A₁C₆₀ is revealed by Magic Angle Spinning NMR, while its magnetic properties are studied by ¹³C and ⁸⁷Rb wideband NMR.     

软模板导向合成多级孔丝光沸石及其苯的苄基化催化性能

通常认为丝光沸石是具有一维孔道结构的微孔沸石, 在涉及大分子的催化反应中存在较为严重的扩散限制。以双季铵型表面活性剂C₁₈H₃₇N⁺(CH₃)₂C₆H₁₂N⁺(CH₃)₂C₆H₁₃(Br^-)₂(C_18-6-6Br₂)作为软模板, 在水热条件下制备了多级孔丝光沸石分子筛。采用XRD、FT-IR、SEM、TEM、TG-DTG、N₂物理吸附、NH₃-TPD等手段对样品的晶体结构和物化性能进行了表征。结果表明, 加入C_18-6-6Br₂制备了纳米棒定向排列的多级孔丝光沸石, 而且可通过改变合成体系中C_18-6-6Br₂/SiO₂的比值, 对样品的晶粒尺寸、介孔表面积和介孔孔容进行系统调变。在苯与苯甲醇的苄基化反应中, 多级孔样品比传统微孔丝光沸石表现出更好的苄基化反应催化性能和显著提高的反应速率。多级孔丝光沸石优异的催化性能归因于介孔的存在使其具有更多的可接近活性位和更优异的质量传输性质, 这种独特的多级孔丝光沸石在大分子催化转化反应中具有较大的应用潜力。     

Magnetic Properties of CsxC60

Magnetic properties of Cs_xC₆₀ have been studies by the magnetic susceptibility and ESR. The observation of Pauli and Curie-Weiss susceptibilities implies the existence of a metallic phase Cs₁C₆₀ and a paramagnetic phase Cs₄C₆₀.     

Thermally Activated Decay Processes of Isolated Superhot C60 in Molecular Beams

We have studied thermally activated decay processes of an ensemble of isolated superhot C₆₀ molecules in molecular beams by several different methods. Highly vibrationally excited C₆₀ molecules in effusive or supersonic beams (with average vibrational energy of 10-20 eV) were generated in an all ceramic, two-stage high temperature nozzle source. the decay kinetics due to various decay processes of the initially canonical ensemble was followed by a mass spectrometric methods for a large range of initial temperatures (T_o=1100 - 1950 K). the processes studied are: (1) fragmentation (C₂ emission) of the neutral C₆₀ (2) C₂ emission from the C⁺₆₀ ions (3) black-body like radiative cooling, and (4) delayed electron emission. the experiments described here are: (a) Depletion of the integrated C₆₀ flux. (b) Analysis of C₆₀ time-of-flight distributions. (c) Dependence of electron impact induced ionization/ fragmentation of C₆₀ upon its initial thermal excitation, and (d) Thermal energy dependence of delayed electron emission. It is shown that thermal kinetics models using a single set of independently measured parameters uniquely reproduce all the experimental observations. the models take into account the different cooling processes and their time evolution. We analyze in detail the evolution of the initially canonical vibrational energy distribution during the flight time to the detector as it is gradually being distorted due to evaporative and radiative cooling mechanisms. It is concluded that the correct parameters to be used for describing the thermally activated decay kinetics of superhot C₆₀ are activation energy of E_o = 4.3 - 4.8 eV for the neutral fragmentation channel C₆₀ → C₅₈ + C₂ and E₁=4.0 - 4.3 for the ion fragmentation channel C⁺₆₀→ C⁺₅₈ + C₂, and corresponding pre-exponential factors of A_o = A₁ = 2.5 × 10¹³ sec^-1. the emissivity coefficient for black body like radiation was found to be ε = 4.5 × 10^-5.     

Eu3+、Dy3+和Er3+对制备堇青石晶相转变的对比表征

以菱镁矿风化石、工业Al₂O₃和SiO₂微粉为原料, 固相反应烧结合成制备堇青石。通过在反应物中分别加入不同含量的Eu₂O₃、Dy₂O₃和Er₂O₃, 研究分析和对比了Eu³⁺、Dy³⁺和Er³⁺对堇青石晶相组成、晶粒大小、晶胞常数、结晶度及显微结构的影响。采用XRD和SEM表征试样中的晶相和显微结构, 利用X'Pert Plus软件对结晶相的晶胞参数和结晶度进行分析, 采用半定量法对试样晶相组成进行计算, 利用Scherrer公式计算堇青石的晶粒大小。结果表明: 由于Eu₂O₃、Dy₂O₃和Er₂O₃的加入, 通过固相反应烧结所得堇青石试样中出现了莫来石相, Eu³⁺、Dy³⁺和Er³⁺对Mg²⁺的置换作用改变了堇青石相晶格常数和晶胞体积。随着添加剂含量的增加, 堇青石结构中液相量增加, 相对结晶度降低, 常温致密度提高, 堇青石晶粒粒径减小。综合对比分析, Eu₂O₃对堇青石晶相转变的影响程度最弱, Er₂O₃对堇青石晶相转变的影响程度最强, 对提高合成堇青石的烧结性和热震稳定性效果最好。     

Investigation of Iron-Fullerene Mixture Plasmas in ECR Discharge

Fullerene+iron (C₆₀+Fe) mixture plasmas were produced and studied in the ECR ion source of ATOMKI. The two main components of the plasma were obtained by different filament ovens. In this series of measurements we concentrated on the maximum ratio of C₅₈ (damaged fullerene) in the plasma. C₅₈ is less stable than C₆₀ and the probability to form new materials is higher. Using this method we produced molecules of mass M=752 both in single- and double-charged states with beam intensities of 8 · 10^-10A and 2 · 10^-10A, respectively. We identified this beam as a mixture of FeC₅₈, O₂C₆₀ and CO₂C₅₉, while the experiment did not give information on the exact location of the iron and oxygen in the carbon ball.     

Phase relations, lattice thermal expansion in Ce1−xEuxO2−x/2 and Ce1−xSmxO2−x/2 systems and stabilization of cubic RE2O3 (RE: Eu, Sm)

The phase relations in CeO₂–Eu₂O₃ and CeO₂–Sm₂O₃ systems have been established under slow-cooled conditions from 1400 °C. The two-phase relations differ as the CeO₂–Eu₂O₃ system showed only two monophasic phase fields, namely F-type cubic and C-type cubic, whereas CeO₂–Sm₂O₃ system showed three phase fields namely F-type cubic, C-type cubic and a biphasic field comprising of C-type cubic and monoclinic phase. An interesting observation of this investigation is the stabilization of C-type rare-earth oxide after Ce⁴⁺ substitution, which is attributed to decrease in average cationic size on Ce⁴⁺ substitution at RE³⁺ site. The lattice thermal expansion behavior of F-type solid solution and C-type solid solution in CeO₂–Eu₂O₃ system was investigated by high-temperature XRD.     

INHIBITORY EFFECTS OF FULLERENE C60 DERIVATIVES ON ENDOTHELIUM-DERIVED RELAXATION IN RABBIT THORACIC AORTA

Inhibitory effects of newly synthesized fullerene C₆₀ derivatives 1 (C₆₀-bis(N,N-dimethylpyrrolidinium iodide)), 2 (C₆₀-proline-N-acetic acid) and 3 (C₆₀-ethylenediamine-N, N'-diacetic acid) on acetylcholine-induced relaxation in endothelium-intact rabbit thoracic aorta precontracted by phenylephrine (10^-6 M) were studied. Fullerene C₆₀ derivative 1 (3 × 10^-6 M), 2 (10^-5 M) and 3 (10^-5 M) reduced the maximum amplitude of the acetylcholine-induced relaxation without significantly changing the pD₂ values obtained from the concentration - response curves. In the presence of fullerene C₆₀ derivative 1 (10^-5 M) the acetylcholine-induced relaxation was eliminated and an acetylcholine-induced contraction was observed. These results suggest that fullerene C₆₀ derivative 1 strongly inhibits endothelium (nitric oxide)-dependent acetylcholine-induced relaxation in thoracic aorta of rabbit.     

Nonlinear Optical Properties of Copolymers of Benzylaminofullerene with Methyl Methacrylate or Ethyl Methacrylate

Nonlinear optical properties of a C₆₀ derivative, benzylaminofullerene [C₆₀H_n(NHCH₂C₆H₅)_n] and its copolymers with methyl methacrylate or ethyl methacrylate were observed carefully by using the nanosecond laser pulses at 532 nm. These copolymers have been proved to be promising materials for optical limiting applications.     

Fabrication of novel bifunctional nanohybrid based on layered rare-earth hydroxide with magnetic and fluorescent properties

We demonstrate the fabrication of a novel magnetic nanohybrid involving the drug molecule 5-aminolevulinic acid (5-ALA) intercalated Gd–Eu layered rare-earth hydroxide (LRH) coated on magnesium ferrite particles (MgFe₂O₄). The structure, thermostability, morphology, luminescence properties, cytotoxic effect and magnetism are investigated. The 5-ALA intercalated composite may correspond to a monolayered vertical arrangement, and the thermal stability of organics is enhanced after intercalation. The LRH precursor shows red emission of Eu³⁺ and the maximum emission peak of the composite is at 451 nm, corresponding to the blue emission. The detection of drug molecules can be realized through the change of luminescence. The magnetic nanohybrid shows strong magnetic sensitivity, which provides an easy and efficient way to separate 5-ALA-MgFe₂O₄@LGd_0.95H:Eu_0.05 particles from a sol or a suspension system and to carry drugs to targeted locations under an external magnetic field. The cytotoxic effect of MgFe₂O₄@LRH is observed with a sulforhodamine B (SRB) colorimetric assay, which has low cytotoxic effects on selected cells. The fabrication of novel bifunctional drug carriers based on LRH with magnetic and fluorescent properties has potential applications in drug detection and drug delivery.     

GROUP TRANSFER AND DIMERIZATION PROCESSES OF C60(CN)2 UNDER ATMOSPHERIC PRESSURE IONIZATION CONDITIONS

Neutral and anionic C₆₀(CN)₂ were investigated with electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) mass spectrometry. It was observed that its anions underwent cyano- group and oxygen transfer, and dimerization processes in ESI conditions to form C₆₀(CN)₃H^-, C₆₀(CN)₂(OH₂)^-, [C₆₀(CN)₃H]^-₂, [C₆₀(CN)₂(OH₂)]^-₂ and [(C₆₀)₂(CN)₂(OH)]^-. Meanwhile, neutral C₆₀(CN)₂, for which no signal was observed in ESIMS, showed a base peak corresponding to C₆₀(CN)₂Cl^- in APCIMS spectra with CHCl₃ used as solvent, while only a molecular ion peak corresponding to C₆₀(CN)^-₂ was observed for the toluene solution of neutral C₆₀(CN)₂ in the same conditions. Possible mechanisms for group transfer and dimerization were proposed based on these observations.     

Penetration of Fullerene C60 Derivatives Through Biological Membranes

Penetration of fullerene C₆₀ in hydrated molecular-colloidal form (FMC) and various C₆₀ water-soluble derivatives (FDs) through membranes of human erythrocytes, platelets and symbiosomes (subcellular organelles of plant origin) were tested. The FDs bearing amino acids induced pronounced depolarization of symbiosome membranes energized with Mg-ATP. In erythrocytes and platelets incubated in K⁺-free medium in the presence of FCCP, FDs with malonic acid pendants promoted acidification of the intracellular medium thereby simulating an effect of the K⁺ ionophore valinomycin. Dissipation of ΔpH artificially induced on the plasma membrane of these cells was observed in the presence of C₆₀-γ-aminobutiric acid which, in addition, strongly stimulated Mg-ATP-dependent generation of membrane potential on symbiosome membranes. C₆₀-Arg was shown to dissipate K⁺-diffusion potential on erythrocyte membranes induced by valinomycin. Fullerene C₆₀ used in hydrated molecular-colloidal form (FMC) also entered symbiosomes and platelets as evidenced by the quenching of the fluorescence of the Ca²⁺ indicator chlorotetracycline localized in the interior of these cells. These findings provide evidence for ease of permeation of these fullerene-based compounds through biological membranes from different type cells.     

Solubility of Fullerenes C60 and C70 in Seven Normal Alcohols and Their Deduced Solubility in Water

The solubilities of C₆₀ and C₇₀ at 25°C in seven normal alcohols obey the relationship InY = a + bX + cX², where Y is solubility and X is the Hildebrand solubility parameter of the solvent. Extrapolation to the solubility parameter of water yields solubilities in water of 1.3'10^-11 (C₆₀) and 1.3'10^-10(C₇₀) ng/ml with an uncertainty of one order of magnitude.     

Preparation and characterization of C60S16 and C70S48 thin films

In this study, we have investigated different methods for preparation of thin films of C₆₀ and C₇₀-sulfur compounds. Films of good quality were obtained by reaction of amorphous C₆₀ and C₇₀ films with a saturated sulfur solution in toluene at 40°C or with saturated sulfur vapour at a temperature of 140°C for several hours. The quality of the fullerene-sulfur films were strongly dependent on the microstructure of the initially deposited fullerene film and the synthesis temperature. X-ray diffraction analyses showed that both methods lead to the formation of films consisting of C₆₀S₁₆ and C₇₀S₄₈ (space groups C 2/c and Amm2, respectively). C₆₀S₁₆ films synthesised on Al₂O₃(012) and Si(100) substrates were texture-free while C₇₀S₄₈ films typically exhibited a preferential (100) orientation. The films were also characterised by Raman and IR- spectroscopy, which confirmed that the interactions between the fullerene molecules and the S₈ rings are weak. The fullerene-sulfur compounds were found to be unstable at high vacuum conditions. Both materials C₆₀S₁₆ and C₇₀S₄₈ are non-conductive at room temperature with conductivities less then 10⁻⁵ (Ω/cm).     

Stone-Wales Rearrangement Pathways from the Hinge-Opened [2+2] C60 Dimer to Ipr C120 Fullerenes. Vibrational Analysis of Intermediates

Possibility of the previously proposed hinge-opened product 2 of [2+2] C₆₀, dimer 1 transforming itself into IPR C₁₂₀ fullerenes by a series of generalized Stone-Wales (GSW) rearrangements has been tested by seeking all topologically acceptable pathways with the help of a graphical search program. the first IPR isomer 4 appeared after 20 GSW steps from the wide-bridged dumb-bell shaped precursor 3. More than 1,000 C₁₂₀ fullerene structures were generated during subsequent ten GSW steps, but the outstanding T_dC₁₂₀ global minimum 5 was not reached. Semiempirical vibrational calculations predict characteristic transition in the vibrational spectra in the course of rearrangement pathway.     

Sr2Si5N8:Eu2+荧光粉的制备及其发光性能研究

以Sr₂CO₃、Si₃N₄和Eu₂O₃为原料, 以C为主要还原剂, 采用碳热还原氮化工艺合成Sr₂Si₅N₈:Eu²⁺荧光粉, 着重研究了C、Sr₂CO₃添加量及Eu²⁺浓度对产物物相及发光性能的影响。研究结果表明: 当C与Si₃N₄的摩尔比 n_c/=9/5时,合成出Sr₂Si₅N₈:Eu²⁺单相荧光粉, 添加适当过量的Sr₂CO₃可提高合成产物的N含量, 且荧光粉的发光强度与其N含量呈现正相关关系。在450 nm蓝光激发下, 受Eu²⁺的4f⁶5d¹ → 4f⁷跃迁作用, Sr₂Si₅N₈:Eu²⁺荧光粉在550~700 nm波段范围产生非对称宽带发射。随着Eu²⁺掺杂浓度由1.5mol%增加到20mol%, 荧光粉的发光强度先增强后减弱, 达到2mol%时发生浓度淬灭现象; 发射主峰由608 nm逐步红移至641 nm; CIE色坐标从(0.606, 0.393)位移至(0.656, 0.343), 是一种可用于白光LED的优质红色荧光粉。     

具有固-液转变的磁性Fe3O4纳米流体的制备、结构及性能

Fe3O4纳米粒子与离子型改性剂N,N-二癸基-N-甲基-N-三甲氧基硅正丙基氯化铵进行接枝反应,再采用反离子脂肪醇聚氧乙烯醚磺酸盐的长链阴离子交换Cl-,在Fe3O4纳米粒子表面得到具有阴、阳离子双电层结构的表面处理层,制备出了无溶剂Fe3O4纳米流体。分析结果表明,表面处理鏖已成功地接枝在Fe3O4纳米粒子表面,改...