This review is focused on charge-transfer reactions at carbon nanotubes and fullerenes. The spectroelectrochemistry of fullerenes deals with the spin states of fullerenes, the role of mono-anions and the reactivity of higher charged states in C60. The optical (Vis-NIR) spectroelectrochemistry of single-walled carbon nanotubes (SWNTs) follows changes in the allowed optical transitions among the Van Hove singularities. The Raman spectroelectrochemistry of SWNT benefits from strong resonance enhancement of the Raman scattering. Here, both semiconducting and metallic SWNTs are analyzed using the radial breathing mode (RBM) and G-modes as well as the second order (D, G') and intermediate frequency modes. Raman spectroelectrochemistry of SWNT allows the addressing of index-identified tubes and even single isolated nanotubes. Optical and Raman spectroelectrochemistry of fullerene peapods, C60@SWNT and C70@SWNT indicates effective shielding of the intratubular fullerene (peas). The most striking effect in the spectroelectrochemistry of peapods is the so-called "anodic Raman enhancement" of intratubular C60. Double-walled carbon nanotubes (DWNTs) give a specific spectroscopic response in Vis-NIR spectroelectrochemistry for the inner and the outer tube. They are better distinguishable by Raman spectroelectrochemistry which allows a precise tracing of the specific doping response of outer/inner tubes. 相似文献
Synthesis of emerald green fullerenes (EF) C60[C(CH3)(CO2Et)2]6 and C60[C(CH3)(CO2-t-Bu)2]6 was performed by using hexaanionic C60 intermediate (C60-6) as a reagent in one-pot reaction for attaching six alkyl ester addends on one C60 cage. These EF compounds exhibit intense optical absorption over 600-940 nm, the longest optical absorption of the C60 cage among many [60]fullerene derivatives synthesized. 相似文献
The dispersion of the otherwise insoluble C60 fullerene in water is discussed. Amphiphilic block copolymers, namely, polystyrene-b-polyethylene oxide (PS-PEO), were found to be able to disperse C60 in aqueous solutions, where the polymer forms micelles with a hydrophobic PS core. The preparation protocol of the final solutions was found to play a crucial role in the ability of the block copolymer to disperse the C60 molecules. The C60 containing aggregates were studied using optical spectroscopy, light scattering, and scanning electron microscopy. In addition, their optical limiting action and nonlinear optical properties under visible nanosecond laser excitation were studied and compared with that of C60-toluene solutions. 相似文献
The molecular orientation of ellipsoidal C(70) in single-walled carbon nanotubes (SWCNTs) depends on the tube diameter (d(t)). Photoluminescence (PL) studies reveal that the fullerene encapsulation effects on the optical transition energy of SWCNTs are significantly different for C(70) and C(60) at d(t) = 1.405-1.431 nm. This indicates that the transition from the "lying" alignment to the "standing" alignment occurs at d(t) ≈ 1.41 nm and the electronic states of SWCNTs are very sensitive to the interspacing between the encapsulated molecules and the SWCNTs. The present findings suggest that the electronic structure of SWCNTs is tunable not only by alternating the encapsulated molecules but also by controlling their molecular orientations, thus paving the way for development of novel SWCNT-based devices. 相似文献
A novel synthetic method combining chemo and enzymatic synthesis strategies was employed to prepare a vinyl acetate type monomer, 6‐(4‐methoxybiphenyl‐4′‐oxy)hexyl vinyl hexanedioate (VA‐LC). Homo‐ and copolymers of VA‐LC with maleic anhydride (MAn) were prepared by conventional free radical polymerization using 2,2′‐azobisisobutyronitrile (AIBN) and 1,1′‐azobis (cyclohexane carbonitrile) (AHCN) as an initiator at 95 and 60 °C, respectively. The thermal properties of the generated polymeric material were investigated by differential scanning calorimetry (DSC), and the optical texture was inspected by polarizing optical microscopy (POM). While the monomer VA‐LC does not exhibit liquid‐crystalline properties, poly(VA‐LC), and the alternating copolymer of VA‐LC with maleic anhydride both displayed such properties.
Low-energy excitations and optical absorption spectrum of C(60) are computed by using time-dependent (TD) Hartree-Fock, TD-density functional theory (TD-DFT), TD DFT-based tight-binding (TD-DFT-TB), and a semiempirical Zerner intermediate neglect of diatomic differential overlap method. A detailed comparison of experiment and theory for the excitation energies, optical gap, and absorption spectrum of C(60) is presented. It is found that electron correlations and correlation of excitations play important roles in accurately assigning the spectral features of C(60), and that the TD-DFT method with nonhybrid functionals or a local spin density approximation leads to more accurate excitation energies than with hybrid functionals. The level of agreement between theory and experiment for C(60) justifies similar calculations of the excitations and optical absorption spectrum of a monomeric azafullerene cation C(59)N(+), to serve as a spectroscopy reference for the characterization of carborane anion salts. Although it is an isoelectronic analogue to C(60), C(59)N(+) exhibits distinguishing spectral features different from C(60): (1) the first singlet is dipole-allowed and the optical gap is redshifted by 1.44 eV; (2) several weaker absorption maxima occur in the visible region; (3) the transient triplet-triplet absorption at 1.60 eV (775 nm) is much broader and the decay of the triplet state is much faster. The calculated spectra of C(59)N(+) characterize and explain well the measured ultraviolet-visible (UV-vis) and transient absorption spectra of the carborane anion salt [C(59)N][Ag(CB(11)H(6)Cl(6))(2)] [Kim et al., J. Am. Chem. Soc. 125, 4024 (2003)]. For the most stable isomer of C(48)N(12), we predict that the first singlet is dipole-allowed, the optical gap is redshifted by 1.22 eV relative to that of C(60), and optical absorption maxima occur at 585, 528, 443, 363, 340, 314, and 303 nm. We point out that the characterization of the UV-vis and transient absorption spectra of C(48)N(12) isomers is helpful in distinguishing the isomer structures required for applications in molecular electronics. For C(59)N(+) and C(48)N(12) as well as C(60), TD-DFT-TB yields reasonable agreement with TD-DFT calculations at a highly reduced cost. Our study suggests that C(60), C(59)N(+), and C(48)N(12), which differ in their optical gaps, have potential applications in polymer science, biology, and medicine as single-molecule fluorescent probes, in photovoltaics as the n-type emitter and/or p-type base of a p-n junction solar cell, and in nanoelectronics as fluorescence-based sensors and switches. 相似文献
Summary: Poly(vinyl acetate) chains end‐capped by a Co(acac)2 complex [PVAc‐Co(acac)2] were prepared by bulk cobalt‐mediated radical polymerization (CMRP) of vinyl acetate and used for grafting fullerene (C60) with four PVAc arms at low temperature (30 °C). A photoactive water‐soluble poly(vinyl alcohol)/C60 nanohybrid was then prepared by hydrolysis of the PVAc arms of the nanohybrid. Because of photoactivity and very low cytotoxicity, this type of water‐soluble nanohybrid is very promising for the photodynamic cancer therapy.
Strategy for the preparation of PVAc/C60 nanohybrid and hydrolysis of PVAc/C60 nanohybrid into PVOH/C60 nanohybrid. 相似文献
A significantly enhanced, ultrafast third-order optical nonlinearity at the wavelengths of 1150-1600 nm was demonstrated with cross-linked C60-containing polyurethane films using the Z-scan technique. Good-quality polymer films with a high loading of C60 derivative were obtained by cross-linking of the hydroxyl-containing C60 derivative and a triisocyanate. The positive Kerr coefficient with nonresonant nonlinear refractive index n2 falls in the range of (3.7 +/- 0.80) x 10-4 to (2.0 +/- 0.6) x 10-3 cm2/GW, and the calculated chi(3) and gamma values are up to 9.7 x 10-11 and 9.6 x 10-32 esu at 1550 nm, which are several orders of enhancement in third-order optical nonlinearity over pristine C60 in solution and 1-2 orders of enhancement over recently reported C60 derivatives and conjugated polymers. 相似文献
The Diels-Alder reaction between C60 and anthryl glycodendron, which has d- or l-gluconamides at the terminals, gave a new fullerene glycodendron conjugate. Interestingly, the diastereoselective cycloaddition reaction proceeded upon the treatment of C60 with the anthryl dendron 3. Furthermore, optical pure fullerodendrons (−)-4L and (+)-4D, which were confirmed by 1H and 13C NMR spectroscopy, FT-IR, MALDI-TOF mass spectroscopic analysis, were isolated from the mixture of diastereomers. And their absolute configurations were predicted by the use of CD spectra. 相似文献
Summary: We illustrate the ink‐jet printing of a thin‐film library of donor/acceptor systems useful in bulk heterojunction solar cells and their characterization utilizing a UV‐vis/fluorescence plate reader and an optical profilometer. In addition, the morphology of the films has been examined by atomic force microscopy (AFM). The ink‐jet processing technology allows printing of arrays of different donor/acceptor compositions on one substrate as well as the subsequent fast optical screening of the electron transfer processes. The investigated films consist of blends of a poly(methyl methacrylate) polypyridyl ruthenium(II ) copolymer (RuPMMA) as electron donor material (p‐type) and C60 fullerene (PC60BM) as well as heptyl viologen (C7‐V) derivatives as electron acceptor materials (n‐type).
Ink‐jet printing process and investigated donor/acceptor pair (RuPMMA‐PC60BM). 相似文献
The first enantiomerically pure and soluble C(60) dimers have been synthesized from suitably functionalized 1,1'-binaphthyl derivatives by 1,3-dipolar cycloaddition of the respective in situ generated diazo compounds to C(60). These systems exhibit optical and electrochemical activity. 相似文献
Fourteen novel complexes of fullerene C(60) with metal dialkyldithiophosphate, {[(RO)(2)PS(2)](2)M}·2C(60) (R = Me and Et; M = Mn, Fe, Co, Ni, Cu, Zn and Pd), can be obtained in high yield by the reaction of metal(II) dialkyldithiophosphate complexes with C(60) fullerene. Their structures are determined by (1)H, (13)C, and (31)P NMR spectroscopy, elemental analysis, FT-IR and UV-vis, and are supplied by single crystal X-ray data. The compound {[(EtO)(2)PS(2)](2)Pd}·2C(60) was also studied by the HRTEM image and SAED patterns. Studies of the optical properties of the complexes of fullerene C(60) with metal dialkyldithiophosphate show that these compounds all have very strong nonlinear optical absorption effects. The nonlinear absorption of fourteen complexes of fullerene C(60) with metal dialkyldithiophosphate (in o-dichlorobenzene and in the solid state) was measured by the open-aperture Z-scan technique at a wavelength of 532 nm. DFT calculations are also used to discuss the stability of these complexes and to confirm the structural assignments. 相似文献
C50Cl10 [S. Y. Xie et al., Science 304, 699 (2004)] has been synthesized in large quantities enabling the capture of the labile fullerene C50. In this Communication, we report ab initio calculations on the optical excitation and absorption spectra of C50Cl10. We successfully explain and assign the measured UV-visible absorption spectrum of C50Cl10. The first singlet excitation for C50Cl10 is optically forbidden, and its optical absorption gap is redshifted by 0.6 eV (110 nm) relative to that of C60. We demonstrate that passivating C50 with 10 hydrogen atoms and replacing one Cl in C50Cl10 by one methoxy group lead to 100 nm blueshift and 90 nm redshift of the optical gap predicted for C50Cl10, respectively, suggesting C50 derivatives are suitable for tunable optical applications. 相似文献
A high-throughput screening method for the exploration of optimal curing parameters and resistance to solvents of NANOMER® coating materials based on the temperature-dependent swellability was developed. The screening method was first tested using a model sol made of pre-hydrolyzed (3-glycidoxypropyl)triethoxysilane (GPTES), tetraethoxysilane (TEOS), (heptadecafluoro-1,1,2,2-tetrahydrodecyl)triethoxysilane (FTS) and zirconium complex (prepared of zirconium-tert-butoxide complexed with acetylacetonate) charged with reactive diluent trimethylolpropan-triglycidether and defined amounts of fluorescein and cured at different temperatures. Afterwards, fluorescein was extracted with sodium hydroxide solution and the optical density of the supernatant of all samples was measured at 490 nm which is sensitive to the dye concentration. The optical density (OD) correlates with the degree of curing. According to this screening a temperature $CDATA \geq 140 ^\circA high-throughput screening method for the exploration of optimal curing parameters and resistance to solvents of NANOMER?
coating materials based on the temperature-dependent swellability was developed. The screening method was first tested using
a model sol made of pre-hydrolyzed (3-glycidoxypropyl)triethoxysilane (GPTES), tetraethoxysilane (TEOS), (heptadecafluoro-1,1,2,2-tetrahydrodecyl)triethoxysilane
(FTS) and zirconium complex (prepared of zirconium-tert-butoxide complexed with acetylacetonate) charged with reactive diluent trimethylolpropan-triglycidether and defined amounts
of fluorescein and cured at different temperatures. Afterwards, fluorescein was extracted with sodium hydroxide solution and
the optical density of the supernatant of all samples was measured at 490 nm which is sensitive to the dye concentration.
The optical density (OD) correlates with the degree of curing. According to this screening a temperature
C is necessary for proper curing. The time dependence of extraction reveals information on resistance against sodium hydroxide
solution, i. e. alkali resistance. The time dependent extraction of fluorescein at
C of coatings cured at 100 and 140°C, respectively, shows a better resistance against 0.1 M sodium hydroxide solution for
the one cured at 140°C, especially in the time range 10–60 min. The whole process — sol preparation, mixing of sols with dye,
extraction, and optical spectroscopy—can be performed automatically. Further testes were made to proof the usability of this
process. 96 hybrid materials were screened in regard to their alkali resistance and finally, a total number of 14 clear organic-inorganic
hybrid coating systems with improved stability against sodium hydroxide solution were derived from this study. 相似文献
Amorphous carbon nitride films with good photoluminescence could be ultrafastly fabricated by liquid-phase electrochemical decomposition of fullerene derivative, C60[(NH2)2CNCN]5. The structure of the as-prepared films, characterized by transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy, was consisted of sp2 hybrid C, sp3 hybrid C, C–N, CN and CN bands. Further study showed that the thickness of the films increased with the increase of the deposition time and the concentration of C60[(NH2)2CNCN]5. The optical tests indicated that the as-obtained films have distinct photoluminescence, no obvious decrease was observed more than one month later. 相似文献
The gas-solid halogenation and hydrohalogenation using microcrystalline cyclodextrin complexes are found to be efficient for production of the optical active halides of ethyltrans-cinnamate in moderate optical yields: On exposure to HBr at 20°C for 15–20 hr, the cinnamate in solid - and -cyclodextrin complexes yields ethyl R-(+)-3-bromo-3-phenylpropanoate in 46% e.e., and S-(–)-enantiomer in 31% e.e., respectively. No addition nor substitution products are obtained with HC1 vapor at 0–50°C for 15–65 hr. Bromination of the -cyclodextrin complex results in the formation of optical active ethylerythro-2,3-dibromo-3-phenylpropanoate, while chlorination gives the optical active mixture oftrans andcis addition products, ethylerythro- andthreo-2,3-dichloro-3-phenylpropanoates in 60–80% yields. Mechanism of chiral induction in the present gas-solid reaction has been proposed on the basis of the crystal structure of the complex. 相似文献