C60氢胺化反应及其在制备含C60功能材料中的应用

C60与胺类化合物的反应是C60衍生化的重要方法。 本文介绍了C60氢胺化反应的一般规律和特点,对C60氢胺化反应在制备含C60高分子功能材料、含C60自组装单分子膜(SAM)、含C60有机/无机纳米材料和C60生物功能材料等方面应用的研究进展作了综述。     

C60掺杂物超导性EHMO晶体轨道研究

本文对晶态C60, K3C60, K6C60, Rb3C60, Rb6C60, RbCs2C60, Rb2CsC60,KRb2C60, K2RbC60, K2CsC60, Na2CsC60, Li2CsC60, Na2RbC60, Na2KC60进行了EHMO三维晶体轨道的能带结构计算。计算结果除了得到能带结构外, 还得到了这类掺杂物的总态密度, 原子与轨道净电荷, 晶体轨道矢量, 单胞内外原子与轨道投影态密度等。利用上述结果不仅可以从理论上说明A3C60的超导性以及C60和A6C60的绝缘性; 而且还得到ln(1/Tc)和-1/NEf之间一种近似的线性关系, 这个结论与BCS理论的预测非常吻合。     

C60-地塞米松的激光激发

利用激光光解装置检测了C60-地塞米松(C60-DE)的苯溶液在355 nm激光照射下产生的激发三重态, 3C60-DE*出现四个吸收峰, 分别位于700、440、350 和310 nm. 在330 nm处观察到了它的漂白吸收最大值, 这与其基态吸收最大值相对应. 3C60-DE*能够将能量转移给O2分子而淬灭. 与3C60*相比, 3C60-DE*的三重态鄄三重态(T-T)淬灭速率常数减小(3C60*为(5.03±1.31)×109 L·mol-1·s-1, 3C60-DE*为(3.53±0.87)×109 L·mol-1·s-1), 而寿命增加了(3C60*为(12.0±2.6) μs, 3C60-DE*为(18.0±3.3) μs), 这可能是C60分子上连接了地塞米松分子后减小了C60球之间碰撞的几率所致.     

A comparison of the photochemical reactivity of N@C60 and C60: photolysis with disilirane

N@C60 has a lower photochemical reactivity toward disilirane than C60, although N@C60 does not differ from C60 in its thermal reactivity; theoretical calculations reveal that N@C60 and C60 have the same orbital levels and that N@3C60* has a shorter lifetime than 3C60*.     

Study of photoinduced electron transfer between [60]fullerene and proton-sponge by laser flash photolysis: addition effects of organic acid

Photoinduced electron-transfer processes between fullerene (C60) and 1,8-bis(dimethylamino)naphthalene, which is called a proton-sponge (PS), have been investigated by means of laser flash photolysis in the presence and absence of CF3CO2H. For a mixture of C60 and PS, the transient absorption spectra showed the rise of the C60 radical anion with concomitant decay of the C60 triplet (3C60), suggesting that photoinduced intermolecular electron transfer occurs via 3C60 in high efficiency in polar solvent. For a covalently bonded C60-PS dyad, photoinduced intramolecular charge-separation process takes place via the excited singlet state of the C60 moiety, although charge recombination occurs within 10 ns. For both systems, electron-transfer rates were largely decelerated by addition of a small amount of CF3CO2H, leaving the long-lived 3C60. These observations indicate that the energy levels for charge-separated states of the protonated PS and C60 become higher than the energy level of the 3C60 moiety, showing low donor ability of the protonated PS. Thus, intermolecular electron-transfer process via 3C60 for C60-PS mixture and intramolecular charge-separation process via 1C60-PS for C60-PS dyad were successfully controlled by the combination of the light irradiation with a small amount of acid.     

Preparation and Application of Immobilized Fullerene C60‐Heparin for Anticoagulation of Blood

The interaction between fullerene C60 and heparin was studied using a fullerene C60‐coated piezoelectric quartz crystal sensor. The irreversible response of the piezoelectric quartz crystal was found which could be attributed to the quite strong adsorption of heparin onto the C60 molecule. Immobilized fullerene C60‐Heparin was prepared and successfully applied as a good inhibitor for blood clotting. Like solvated heparin, both wet and dry C60‐heparin solid all demonstrated excellent ability of anticoagulation of blood. The blood clotting time with C60‐heparin solid was found to be > 7 days, while only 17.9 min required for blood clotting time in the absence of C60‐heparin solid. Furthermore, the C60‐heparin coated artificial PVC blood vessels were prepared by coating fullerene C60 onto the surface of artificial PVC blood vessels, followed by the adsorption of water solvated heparin onto the fullerene C60 molecule to form C60‐heparin coating. The blood clotting time of blood in artificial PVC blood vessels with C60‐heparin coating was found to be > 30 days, while only ≤ 30 min. of blood clotting time without the C60‐Heparin coating was observed. The C60‐heparin coated artificial PVC blood vessels can be expected to be employed in human body for the anticoagulation of blood.     

C60与环己烷及环己烯离子体系的气相反应

在气相条件下研究了C60与环己烷及环己烯的离子-分子反应。C60可与上述体系中多种离子发生反应, 生成相应的加合离子, 表现出C60化学性质的活泼性和多样性。C60与C4H7^+和C5H7^+离子反应可能生成[2+4]环加成的加合离子。     

Wavelength-dependent fragmentation and clustering observed after femtosecond laser ablation of solid C60

We report here the resonance effect in femtosecond laser ablation of solid C60 by investigating wavelength and fluence dependence of product ion species. When the ablation laser wavelength is far from the molecular absorption band of C60, we observe both C60-2n+ fragment ions and C60+2n+ cluster ions as well as C60+ parent ion. Delayed ionization of C60 is not significant. When the ablation laser wavelength is near resonant with the molecular absorption, we observe C60+ and some amount of C60-2n+ fragment ions depending on the laser fluence. Delayed ionization of C60 is significant in this case, which indicates high internal energy of C60 molecule. From the observations, we confirm the strong coupling of femtosecond laser energy with C60 molecule when the molecular absorption is high at the ablation laser wavelength.     

C_（60）－PNVC光电导功能材料的形态与结构研究

用高分辨~（１３）Ｃ核磁共振技术与扫描电镜法研究了Ｃ_（６０）修饰的聚乙烯咔唑（ＰＮＶＣ）光电导功能材料。结果表明，Ｃ_（６０）与ＰＮＶＣ共混时彼此间存在快速动态电荷转移行为；Ｃ_（６０）含量对化学修饰的ＰＮＶＣ结构影响显著。最后比较了Ｃ_（６０），ＰＮＶＣ及用金属有机化学法制备Ｃ_（６０）－ＰＮＶＣ共聚物的亚微观形态结构差异。     

立方面心C60晶体晶格振动的研究

采用C60分子之间相互作用势的Kihra形式,研究了立方面心C60晶体的晶格振动问题,得到了质心振动沿[111]、[110]及[100]方向的声子散射圆频率分布曲线及C60晶格振动频率的态密度分布.采用所得到的C60晶格振动频率的态密度分布,计算了晶体C60在298 K时的等压热容,所得数值与实验值相符.     

Transient species of fullerenes studied with pulse radiolysis and laser photolysis

The excited triplet of C60 or C70 is generated via either direct excitation by laser light or energy transfer from excited states of solvent to C60 and C70. The cation radical of C60 is produced either via hole transfer from cation radical of CCl4 to C60 or via electron transfer from excited triplet of C60 to CCl4. C60 and C70 could be added to trichloromethyl radical to produce adduct radicals with different mechanisms.     

Gas-phase observation of multiply charged C60 anions

Gas-phase observation of C60(1-), C60(3-), and C60(4-) anions generated at platinum and gold electrodes and detected by electrochemical/electrospray mass spectrometry is reported. The anions were electrochemically generated from solutions of C60 dissolved in toluene/acetonitrile as well as from reduction of C60 films on gold electrode surfaces. The gas-phase observation of C60(3-) and C60(4-), despite the fact that they have negative electron affinities, is a result of a Coulombic barrier to electron loss. The fact that C60(2-) was not detected in these experiments is ascribed to its limited solubility under the reaction conditions. These studies, which demonstrate the gas-phase kinetic stability of C60(3-) and C60(4-), illustrate the promise of electrochemical/electrospray mass spectrometry for the study of metastable anions.     

Fullerenes制备中C60和C70含量不同的热力学解释

本文计算了不同温度下气相反应7/6 C60=C70的热力学函数, 讨论了C60与C70之间相互转化的热力学条件。结果表明, 温度高于2828K时气相中C60比C70稳定, 温度低于2828K时气相中C70比C60稳定, 解释了由石墨制备Fullerenes时, C60和C70含量不同的原因。     

Artifacts in the electron paramagnetic resonance spectra of C60 fullerene ions: inevitable C120O impurity

Aspects of the electron paramagnetic resonance (EPR) spectra of C60n- fulleride ions (n = 2, 3) and the EPR signal observed in solid C60 are reinterpreted. Insufficient levels of reduction and the unrecognized presence of C120O, a ubiquitous and unavoidable impurity in air-exposed C60, have compromised most previously reported spectra of fullerides. Central narrow line width signals ("spikes") are ascribed to C120On- (n = odd). Signals arising from axial triplets (g approximately 2.0015, D = 26-29 G) in the spectrum of C602- are ascribed to C120On- (n = 2 or 4). Their D values are more realistic for C120O than C60. Less distinct signals from "powder" triplets (D approximately 11 G) are ascribed to aggregates of C120On- (n = odd) arising from freezing nonglassing solvents. In highly purified samples of C60, we find no evidence for a broad approximately 30 G signal previously assigned to a thermally accessible triplet of C60(2-). The C60(2-) ion is EPR-silent. Signals previously ascribed to a quartet state of the C60(3-) ion are ascribed to C120O4-. Uncomplicated, authentic spectra of C60- and C60(3-) become available when fully reduced samples are prepared under strictly anaerobic conditions from freshly HPLC-purified C60. Solid off-the-shelf C60 has an EPR signal (g approximately 2.0025, DeltaH(pp) approximately 1.5 G) that is commonly ascribed to the radical cation C60*+. This signal can be reproduced by exposing highly purified, EPR-silent C60 to oxygen in the dark. Doping C60 with an authentic C60*+ salt gives a signal with much greater line width (DeltaH(pp) = 6-8 G). It is suggested that the EPR signal in air-exposed samples of C60 arises from a peroxide-bridged diradical, *C60-O-O-C60* or its decomposition products rather than from C60*+. Solid-state C60 is more sensitive to oxygen than previously appreciated such that contamination with C120O is almost impossible to avoid.     

Stabilities of multiply charged dimers and clusters of fullerenes

The authors find even-odd variations as functions of r (...+[C60]2(r+)([C60C70](r+)) electron-transfer collisions. This even-odd behavior is in sharp contrast to the smooth one for fullerene monomers and may be related to even-odd effects in dimer ionization energies in agreement with results from an electrostatic model. The kinetic energy releases for dimer dissociations [predominantly yielding intact fullerenes [C60]2(r+)-->C60(r1+)+C60(r2+) in the same (r1=r2) or nearby (r1=r2+/-1) charge states] are found to be low in comparison with the corresponding model results indicating that internal excitations of the separating (intact) fullerenes are important. Experimental appearance sizes for the heavier clusters of fullerenes [C60]n(r+) (n>3 and r=2-5) compare well with predictions from a new nearest-neighbor model assuming that r unit charges in [C60]n(r+) are localized to r C60 molecules such that the Coulomb energy of the system is minimized. The system is then taken to be stable if (i) two (singly) charged C60 are not nearest neighbors and (ii) the r C60(+) molecules have binding energies to their neutral nearest neighbors which are larger than the repulsive energies for the (r-1) C60(+)-C60(+) pairs. Essential ingredients in the nearest-neighbor model are cluster geometries and the present results on dimer stabilities.     

Detection of Hydrogen Peroxide and Glucose Based on Immobilized C60‐Catalase Enzyme

The interaction between fullerene C60 and catalase enzyme was studied with a fullerene C60‐coated piezoelectric (PZ) quartz crystal sensor. The partially irreversible response of the C60‐coated PZ crystal sensor for catalase was observed by the desorption study, which implied that C60 could chemically react with catalase. Thus, immobilized fullerene C60‐catalase enzyme was synthesized and applied in determining hydrogen peroxide in aqueous solutions. An oxygen electrode detector with the immobilized C60‐catalase was also employed to detect oxygen, a product of the hydrolysis of hydrogen peroxide which was catalyzed by the C60‐catalase. The oxygen electrode/C60‐catalase detection system exhibited linear responses to the concentration of hydrogen peroxide and amount of immobilized C60‐catalase enzyme that was used. The effects of pH and temperature on the activity of the immobilized C60‐catalase enzyme were also investigated. Optimum pH at 7.0 and optimum temperature at 25 °C for activity of the insoluble immobilized C60‐catalase enzyme were found. The immobilized C60‐catalase enzyme could be reused with good repeatability of the activity. The lifetime of the immobilized C60‐catalase enzyme was long enough with an activity of 93% after 95 days. The immobilized C60‐catalase enzyme was also applied in determining glucose which was oxidized with glucose oxidase resulting in producing hydrogen peroxide, followed by detecting hydrogen peroxide with the oxygen electrode/C60‐catalase detection system.     

Photoinduced processes in a tricomponent molecule consisting of diphenylaminofluorene-dicyanoethylene-methano[60]fullerene

Photoinduced intramolecular processes in a tricomponent molecule C60(>(CN)2-DPAF), consisting of an electron-accepting methano[60]fullerene moiety (C60>) covalently bound to an electron-donating diphenylaminofluorene (DPAF) unit via a bridging dicyanoethylenyl group [(CN)2], were investigated in comparison with (CN)2-DPAF. On the basis of the molecular orbital calculations, the lowest charge-separated state of C60(>(CN)2-DPAF) is suggested to be C60*-(>(CN)2-DPAF*+) with the negative charge localized on the fullerene cage, while the upper state is C60(>(CN)2*--DPAF*+). The excited-state events of C60(>(CN)2-DPAF) were monitored by both time-resolved emission and nanosecond transient absorption techniques. In both nonpolar and polar solvents, the excited charge-transfer state decayed mainly through initial energy-transfer process to the C60 moiety yielding the corresponding 1C60, from which charge separation took place leading to the formation of C60*-(>(CN)2-DPAF*+) in a fast rate and high efficiency. In addition, multistep charge separation from C60(>(CN)2*--DPAF*+) to C60*-(>(CN)2-DPAF*+) may be possible with the excitation of charge-transfer band. The lifetimes of C60*-(>(CN)2-DPAF*+) are longer than the previously reported methano[60]fullerene-diphenylaminofluorene C60(>(C=O)-DPAF) with the C60 and DPAF moieties linked by a methanoketo group. These findings suggest an important role of dicyanoethylenyl group as an electron mediating bridge in C60(>(CN)2-DPAF).     

Formation of one-dimensional C60 rows on TiO2(110)-1 x 2-cross-link structure and their local polymerization

Adsorption and growth of a C(60) monolayer on a TiO(2)(110)-1 x 2-cross-link structure were investigated by scanning tunneling microscopy (STM). Single C(60) molecules were preferentially anchored at the cross-link site due to interaction with undercoordinated Ti cations, and C(60) rows grew along the troughs between the 1 x 2-added rows. The C(60) monolayer structure is characterized by closely packed (r(C(60)-C(60)) = 1.0 nm) C(60) rows that are paired with every second added row (separation of paired rows is 1.1 nm). By applying a high negative bias voltage (-3.5 V) to an STM tip on the C(60) monolayer, C(60) oligomers were formed accompanied with the contraction of C(60)-C(60) distance along the C(60) row and bright contrast in the STM image.     

异咯嗪修饰富勒烯-聚丙烯酸的合成及其与DNA的相互作用

利用自由基聚合反应合成了聚丙烯酸修饰的富勒烯(C₆₀-PAA),进一步通过酯化反应将核黄素类似物6,7-二甲基-9-(2’-羟乙基)-异咯嗪(DHIX)与C₆₀-PAA共价连接,得到C₆₀-PAA-DHIX.利用傅立叶红外光谱(FT-IR)、核磁共振氢谱(¹HNMR)、紫外-可见吸收光谱(UV-Vis)、荧光光谱对产物的化学结构进行了表征.循环伏安法表明,C₆₀-PAA-DHIX中富勒烯基团的第一还原电位要高于DHIX基团的第一还原电位.ESR实验表明C₆₀-PAA-DHIX能与N,N-二甲基苯胺发生多步光诱导电子转移反应,即DHIX基团与N,N-二甲基苯胺发生光诱导电子转移生成DHIX负离子自由基(DHIX^-·),DHIX^-·能进一步将电子传递给富勒烯生成富勒烯负离子自由基.DNA熔解曲线、紫外-可见吸收光谱和荧光光谱结果表明,C₆₀-PAA-DHIX通过沟槽结合与CTDNA作用,而C₆₀-PAA与DNA的作用较弱.无氧条件下,C₆₀-PAA-DHIX具有比C₆₀-PAA更强的DNA光损伤能力.     

Prolongation of the lifetime of the charge-separated state at low temperatures in a photoinduced electron-transfer system of [60]fullerene and ferrocene moieties tethered by rotaxane structures

A rotaxane tethering both fullerene (C60) and ferrocene (Fc) moieties (abbreviated as (C60;Fc)rotax+) was synthesized in a good yield by the urethane end-capping of pseudorotaxane based on the crown ether-secondary amine motif. In (C60;Fc)rotax+, the C60 group serving as an electron acceptor is attached to the crown ether wheel, through which the axle with a Fc group acting as an electron donor on its end penetrates. The intrarotaxane photoinduced energy-transfer and electron-transfer processes between C60 and Fc in (C60;Fc)rotax+ have been investigated by time-resolved transient absorption and fluorescence measurements with changing solvent polarity. Nanosecond transient absorption measurements of the rotaxane demonstrated that the charge-separated state (C60*-;Fc*+)rotax+ is formed mainly via the excited triplet state of C60 in polar solvents. The lifetime of (C60*-;Fc*+)rotax+ was evaluated to be 20 ns in dimethylformamide (DMF) at room temperature. With lowing temperature, the lifetime of (C60*-;Fc*+)rotax+ extends to 270 ns in DMF at -65 degrees C, due to the structural changes leaving C60*- and Fc*+ at a relatively long distance in the low-temperature region.