Photoconductivity of fullerene derivatives

Two fullerene derivatives (compounds 1 and 2) have been synthesized. Their redox properties have been measured by cyclic voltammetry. The photoconductivities of poly(N_vinylcarbazo_le) (PVK) doped with fullerene and with their derivatives have been studied to explore the possible relationship between the reductibility of fullerenes and the photoconductivity of fullerenes_doped PVK. The charge generation efficiencies of PVK doped with fullerene and with its derivatives have changed remarkably: the diversity of charge generation efficiency is obvious in different doping systems. The result indicates that there is charge transfer between fullerenes and PVK.     

富勒烯[ 60] 与电子给体电荷转移络合物的特性

通过毫微秒激光光解作用研究了富勒烯[60]电荷转移络合物的特性，在苯腈溶液中，从电子给体(TTF)到富勒烯[60]激发三线态的电子转移反应已被观察到，富勒烯[60]激发三线态的消失和富勒烯[60]阴离子自由基的出现，通过瞬态吸收光谱得到证实。     

Superconductivity in single crystals of the fullerene C70.

The observation of superconductivity in doped C60 has attracted much attention, as these materials represent an entirely new class of superconductors. A maximum transition temperature (Tc) of 40 K has been reported for electron-doped C60 crystals, while a Tc of 52 K has been seen in hole-doped crystals; only the copper oxide superconductors have higher transition temperatures. The results for C60 raise the intriguing questions of whether conventional electron-phonon coupling alone can produce such high transition temperatures, and whether even higher transition temperatures might be observed in other fullerenes. There have, however, been no confirmed reports of superconductivity in other fullerenes, though it has recently been observed in carbon nanotubes. Here we report the observation of superconductivity in single crystals of electric-field-doped C70. The maximum transition temperature of about 7 K is achieved when the sample is doped to approximately four electrons per C70 molecule, which corresponds to a half-filled conduction band. We anticipate superconductivity in smaller fullerenes at temperatures even higher than in C60 if the right charge density can be induced.     

Synthesis and Characterization of [60]Fullerene Ferrocenylmethyl Derivatives

Two new [60]fullerene ferrocenylmethyl derivatives have been prepared via different approaches and characterized by UV-Vis、 FT-IR、 NMR、 FAB-MS spectra and VPO. The second approach , i.e reacting fullerene with ferrocenylmethyl azide directly, was never reported as yet.     

Synthesis and characterization of [60]fullerence ferrocenylmethyl derivatives

Two new [60]fullerene ferrocenylmethyl derivatives have been prepared via different approaches and characterized by UV-Vis, FT-IR, NMR, FAB-MS spectra and VPO. The second approach, i.e. reacting fullerene with ferrocenylmethyl azide directly, was never reported as yet. Foundation item: Supported by the Fund for Ph. D Programme from Ministry of Education, P. R. China (98048624) Biography: Li Xin-hong (1973-), female, Ph. D candidate, research direction: fullerene chemistry.     

Influence of organic acids on UV-Vis spectra of pyrrolidino-[60]fullerene derivatives

A pyrrolidino[60]fullerene 1 with pyrrolidine group was synthesized and characterized. The UV-Vis spectra showed that the blue shift of absorption peaks was first observed when strong organic acids such asp-toluene sulfonic or trifluoroacetic acid were added to the solution of pyrrolidino[60]fullerene 1 in dichloromethane. The results indicated that the pyrrolidino[60]fullerene derivatives without pyrrolidine group also possess the same phenomenon. Experiments and computation with the MOPAC 7.0 semi-empirical PM3 method demonstrated the reason that some energy gaps on [60] fullerene skeleton were increased because electronic charges on [60] fullerene framework transferred to pyrrolidine ring when strong organic acids were added into pyrrolidino[60]fullerene derivatives’ solution; as the result, the complexes could be formed and some absorption wavelengths blue shifted in the UV-Vis spectrum.     

Theoretical study on photophysical property of C60M（CO）5 （M=Cr,Mo and W）

Configurations of three η2 models of transition-metal [60]fullerene derivatives C60M（CO）5（M=Cr, Mo and W） have been optimized at B3LYP/LanL2DZ level. On the basis of the optimized geometrical structures, their electronic spectra and the frequency dependence of third-order nonlinear optical polarizabilities γ in different optical processes of third-harmonic generation （THG）, electric-field-induced second-harmonic generation （EFISHG） and degenerate four-wave mixing （DFWM） are calculated by using TDB3LYP model based on LanL2DZ level coupled with the SOS （sum-over-state） method. The obtained results show that their electronic spectra have a red shift compared with that of [60]fullerene and different transition-metal functional groups added to C60 cage may result in different spectrum properties. For the three studied species, （η^2-C60）Mo（CO）5 has the largest third-order nonlinear optical polarizability.     

Fullerenes from aromatic precursors by surface-catalysed cyclodehydrogenation

Graphite vaporization provides an uncontrolled yet efficient means of producing fullerene molecules. However, some fullerene derivatives or unusual fullerene species might only be accessible through rational and controlled synthesis methods. Recently, such an approach has been used to produce isolable amounts of the fullerene C(60) from commercially available starting materials. But the overall process required 11 steps to generate a suitable polycyclic aromatic precursor molecule, which was then dehydrogenated in the gas phase with a yield of only about one per cent. Here we report the formation of C(60) and the triazafullerene C(57)N(3) from aromatic precursors using a highly efficient surface-catalysed cyclodehydrogenation process. We find that after deposition onto a platinum (111) surface and heating to 750 K, the precursors are transformed into the corresponding fullerene and triazafullerene molecules with about 100 per cent yield. We expect that this approach will allow the production of a range of other fullerenes and heterofullerenes, once suitable precursors are available. Also, if the process is carried out in an atmosphere containing guest species, it might even allow the encapsulation of atoms or small molecules to form endohedral fullerenes.     

掺杂C60的聚乙烯基咔唑光导光膜的光电子能谱

采用Ｘ－射线光电子能谱表面分析技术并通过变温手段研究了聚乙烯基咔唑（ＰＶＫ）与Ｃ６０的作用形态，结果表明，ＰＶＫ与Ｃ６０可以形成电荷转移络合物，并且它的形成和解离随着温度的变化是可逆的。ＰＶＫ与Ｃ６０的电荷转移络合物的形成可能是改善ＰＶＫ光电性能的关键所在。     

富勒烯[4,6]-(C24)n(n=1,2,4,8)及相应的BN团簇的理论研究

用AM1半经验量子化学方法,对富勒烯[4,6]-(C₂₄)_n(n=1,2,4,8)及相应的BN完全取代物进行几何构型优化和频率分析.计算结果表明,BN团簇及相应的全碳富勒烯的稳定性均随对称性的变化而呈现相似的递变规律;BN取代增强了体系的稳定性,使得BN团簇有望在实验室中得到;各分子的净电荷分布为实验室寻找分子反应的活性部位提供了理论依据.[     

Controlled fabrication of fullerene derivative one-dimensional nanostructures via electrophoretic deposition of its clusters

Well-defined and controllable one-dimensional(ID) nanostructures of fullerene derivative have been prepared by an electrophoretic template synthesis method. The clusters of fullerene derivative formed in mixed solvents are introduced into the channels of porous alumina templates through a dc electric field. Four types of ID nanostructures(solid nanowires, solid-wall nanotubes, porous nanowires and porous-wall nanotubes) have been obtained by changing the deposition parameters. This,approach opens a new avenue to assemble fullerene derivatives, endohedral fullerenes, as well as other functional organic compounds, which can form clusters in ID nanostructure arrays for applications in chemical sensors, light energy conversion devices and nanoscale electronic and optoelectronic devices.     

富勒烯新结构的研究进展

富勒烯Cn是一类由12个五元环和若干六元环组成的笼状全碳分子.根据碳笼表面是否含相邻分布的五元环,富勒烯可分为IPR富勒烯和非IPR富勒烯.25年来,人们在发展富勒烯合成新方法和寻找富勒烯新结构方面做了大量的工作,富勒烯家族得到了很大的扩充,越来越多的富勒烯新结构被陆续发现和分离出来.迄今为止,已分离、表征了C20~C104的60余种富勒烯新结构,包括40余种IPR富勒烯结构,以及通过笼外化学修饰或内嵌原子(或原子簇)的稳定化策略合成的20余种违反IPR规则的富勒烯.详细总结了这些迄今为止已报道的各种富勒烯新结构,并对今后富勒烯研究的重点和内容进行了预测.     

Inhibition of M-MuLV reverse transcriptase activity by fullerene derivatives

The biological properties and biomedical application of fullerene (C60) and its derivatives are currently very active subjects concerning fullerene research. The bio logical effects of fullerene and its derivatives include enzyme inhibition, sites-selective DNA cleavage, antibacterial and antiviral activities, photocytotoxicity and antiapoptosis[1―4]. Especially, enzymes inhibited by fullerene derivatives mainly consist of oxidation-reduc- tion related enzymes such as glutathione transferase…     

掺杂C60的PVK及其共聚物的光电导性能

通过自由基共聚合的方法制备了一系列乙烯基咔唑／丙烯酸丁酯（ＮＶＣ／ＢＡ）的共聚物,发现ＮＶＣ能和ＢＡ进行较好的共聚合反就投料比和共聚产物中的各单元组成比接近。通过ＴＥＭ观察。加入的共聚单体ＢＡ可以大大改善了聚乙烯基咔唑（ＰＶＫ）的成膜性能。也对掺有Ｃ６０的ＰＶＫ的均聚和共取物的光电导性能进行了研究。实验结果表明Ｃ５０的加入可以大大增进ＰＶＫ的光电导性能,并且随着Ｃ６０的增加光电导性能增强;共聚体系     

富勒烯(C60/C70)与 N,N,N′,N′-四-(对甲基苯)-4,4′-二胺-1,1′-二苯碲醚电荷转移复合物的特征

用激光光解方法研究了富勒烯(C60 / C70)与N,N,N′,N′-四-(对甲基苯)-4,4′-二胺-1,1′-二苯碲醚电荷转移复合物的特征. 通过观察在近红外区瞬间吸收带,富勒烯(C60 / C70)激发三线态,富勒烯(C60 / C70)阴离子自由基和N,N,N′,N′-四-(对甲基苯)-4,4′-二胺-1,1′-二苯碲醚阳离子自由基的出现,测定了在苯腈溶液中从N,N,N′,N′-四-(对甲基苯)-4,4′-二胺-1,1′-二苯碲醚到富勒烯(C60 / C70)激发三线态的量子转化产率和电子转移常数.     

富勒烯科学的若干研究进展

富勒烯的三维空间构型和众多的双键为富勒烯科学的发展提供了广阔的空间，内嵌富勒烯则可以通过控制笼内包合的原子来调节富勒烯的电子结构和还原性质。目前，富勒烯的研究主要集中在富勒烯和金属富勒烯基新型功能材料的合成表征以及应用，其中以设计新的富勒烯／金属富勒烯材料用于化学传感器、太阳能电池及其它器件为主要研究焦点。旨在对目前富勒烯科学的发展与应用研究作一综述介绍。     

C60多氨多羧酸衍生物的合成及其LB膜性质

光照条件下C₆₀能与一系列氨基多羧酸反应生成单加成衍生物。利用这一方法合成了一系列C₆₀氨基多羧酸衍生物。如甘氨酸脂与C₆₀光照下反应生成C₆₀(ROOCCHNHCHCOOR),该反应机理比较复杂,其他的亚氨基及次氨基羧酸脂的反应机理相对较简单。EDTA甲脂与C₆₀光照下反应生成C₆₀[(MeOOCCH)₂NCH₂CH₂N(CH₂COOMe)₂],净的结果就是EDTA失去2个H原子。这些含强亲水基团的C₆₀多羧基衍生物都有很好的成膜性能,能够生成稳定且易转移的单分子膜。通过使用金属离子溶液作为亚相,可在空气/水界面制备相应金属离子的C₆₀衍生物配合物膜。LB膜的光电测定结果表明大部分C₆₀衍生物均具有阴极光电流,即电子从电解质流经LB膜再流向电极,最高光电转换量子产率为8%左右。     

掺杂聚合物对有机电致发光二极管的影响

利用甩胶方法在导电玻璃上分别制得单一的聚烷基噻吩并在其中掺杂不同量的聚乙烯咔唑的有机发光层，再用真空蒸发方法将铝沉积在这些有机层上作为发光二极管的负极。选择合适的掺杂比，电致发光二极管在电压为５Ｖ、电流密度为３０ｍＡ／ｃｍ＾２时就有光输出。这一结果表明，掺杂具有空穴特性的聚乙烯咔唑对增强短烷基侧链的聚烷基噻吩电致发光强度是一种有效的方法。     

Fullerenes C60 and C70 in flames

The fullerenes C60 and C70 were first identified in carbon vapour produced by laser irradiation of graphite, and have recently been produced in macroscopic quantities by vaporization of graphite with resistive heating. It has also been suggested that fullerenes might be formed in sooting flames, and indeed all-carbon ions with mass/charge ratios suggestive of fullerenes have been detected in flames. These species were assumed to have the cage structures of fullerenes, but the mass spectroscopic evidence could not establish this conclusively. We have now collected samples of condensible compounds and soot from hydrocarbon combustion under a range of conditions, and analysed these using conventional techniques in an effort to detect fullerenes. Spectroscopic studies reveal the presence of C60 and C70 in yields and ratios that depend on temperature, pressure, carbon/oxygen ratio and residence time in the flame. Control of these conditions allows optimal yields of 3 g of fullerenes per kilogram of fuel carbon burned, and variation of the C70/C60 ratio over the range 0.26-5.7.     

Solvothermal synthesis of CdS nanorods and photovoltaic characteristics of CdS/PVK composite system

Large quantities of CdS nanorods are successfully synthesized through Cd（CH3COO）2·2H2o reacting with Na2S·9H2O and EDA in aqueous solution. XRD result shows that the sample is of hexagonal structure. And TEM result shows that the morphologies of the resulting CdS are mainly in three-armed rod-like structure with a diameter of 10--15 nm and a length of 100 nm. The nanocomposites of CdS/PVK with different molar ratios are prepared by spin coating method on tin-doped indium oxide （ITO） substrate. A notable decrease of photoluminescence （PL） efficiency and a significant enhancement of surface photovoltage signal have been observed in CdS/PVK composites when the molar fraction of CdS increases. We interpret these results as the energy level matching between CdS and PVK in nanocomposites. This energy level matching facilitates fast interfacial charge transfer then increases the separation efficiency of electron-hole pairs and the carrier generation efficiency. The detailed charge transfer process has also been demonstrated.