Synthesis,Spectral Investigations,and Thermal Stability of [60]Fullerene Complexes with TMTSF: 2(C60) · 2(TMTSF) · (C6H6), C60 · TMTSF · 2(CS2), and 2(C60) · 2(TMTSF) · (C6H5Cl)

Abstract

Molecular complexes of [60]fullerene with tetramethyltetraselenafulvalene (TMTSF): C₆₀ · (TMTSF) · 2(CS₂) (1), 2(C₆₀) · (2(TMTSF) · (C₆H₆) (2), and 2(C₆₀) · (2(TMTSF) · (C₆H₅Cl) (3) have been synthesized and their thermal stability and IR spectra vs. light polarization and temperature have been performed.     

The New Method for the Synthesis of Fullerols Based on Radical Reaction

Abstract

The method for the synthesis of fullerols C₆₀(OH) _x was developed, allowing to obtain products with low number of hydroxy groups attached to fullerene molecule. At the first stage, product C₆₀(tert‐BuO) _x was obtained by the radical reaction of C₆₀ with tert‐butyl‐peroxide under heating or UV‐irradiation. At the second stage, fullerol C₆₀(OH) _x was synthesized after the elimination of tert‐butyl groups by acid treatment. Several samples C₆₀(OH) _x containing different numbers (x = 2–5) of hydroxy groups were obtained, the main product had x = 2. The structure of the fullerols was confirmed by UV‐ and Fourier‐transform infrared (FTIR)‐spectroscopy and MALDI‐TOF mass‐spectrometry.     

Charge recombination reduction in dye-sensitized solar cells by depositing ultrapure TiO2 nanoparticles on “inert” BaTiO3 films

Ultrapure TiO₂ nanoparticles (∼5 nm in size) were supported on “inert” BaTiO₃ films by TiCl₄ treatment, which was used to fabricate dye-sensitized solar cells (DSSCs). The optimized electrode, designated as BaTiO₃/TiO₂(4), was obtained upon four cycles of TiCl₄ treatment. DSSC with BaTiO₃/TiO₂(4) electrode exhibits superior power conversion efficiency (PCE) compared to that with conventional anatase TiO₂ (∼25 nm in size) electrode. The interfacial charge recombination kinetics was investigated by electrochemical impedance spectroscopy (EIS) and intensity-modulated photocurrent/photovoltage spectroscopy (IMPS/IMVS). In contrast to DSSC with anatase TiO₂ electrode, the dramatically enhanced electron lifetime for DSSC with BaTiO₃/TiO₂(4) electrode could be attributed to the decrease of recombination reaction at the TiO₂ photoelectrode/electrolyte interface. It is proposed that the lower interfacial charge recombination can be related to the relatively shallower trap distributions in DSSC with BaTiO₃/TiO₂(4) electrode.     

STM observation of zinc(II) bridled chiroporphyrin molecules on titanium dioxide surface

Zinc bridled chiroporphyrin (ZnBCP-8) molecules on a rutile titanium dioxide (TiO₂)(110)-(1 × 1) surface were successfully observed by scanning tunneling microscopy (STM) under ultrahigh vacuum conditions. The molecules were selectively adsorbed on the surface apparently due to a molecule-substrate interaction. The origin of the interaction is thought to be Coulomb force between molecule and oxygen vacancy on the TiO₂ surface. STM imaging revealed a selective molecular orientation on the TiO₂(110)-(1 × 1) structure. These results support the possibility of manipulating molecules on the surface and constructing well designed molecular structures by controlling the molecular-substrate and intermolecular interactions.     

Novel Fullerene Containing Liquid Crystalline Dendrimers and Hemi‐dendrimers: Synthesis and Characterization

Abstract

Novel fullerene C₆₀ containing liquid crystalline dendrimers and hemi‐dendrimers have been characterized by the method of electro‐optical Kerr effect and determination of the permanent dipole moment, sensitive to the molecular polar ordering and anisotropy of polarizability, and by hydrodynamic methods in solution. An influence of the covalently bonded fullerene on the polarity, electro‐optical, and viscometric properties of fullerene derivatives have been detected, analyzed, and concluded that fullerene produces a change in the original ordering in dendritic molecules, which mainly resulted in correction of the shape asymmetry of these molecules as a whole.     

New Polymeric Phase in Low‐Doped Lithium Intercalated Fullerides

Abstract

The low‐doped Li _x C₆₀ compounds (x≤6) were investigated using laboratory X‐ray and synchrotron radiation diffraction, ¹³C NMR and Raman spectroscopy. Li₄C₆₀ shows an unusual 2D polymerisation in which the C₆₀ units are connected both by [2+2] cycloaddition and by single carbon–carbon bonds, a unique feature among the known polymerised fullerene compounds. This picture is fully supported also by static NMR and Raman measurements. The charge transfer to C₆₀ in the polymeric phase was evaluated from the shift of the A_g(2) mode. The depolymerisation process was investigated as well; despite the presence of two different bonds, the polymer‐to‐monomer transition induced by thermal treatments is a single‐step phenomenon.     

GENERATION OF HIGHER FULLERENES FROM LASER ABLATION OF CARBYNE AND C60 PHOTOPOLYMER ASTROCHEMICAL IMPLICATIONS

ABSTRACT

Laser ablation of targets of carbonaceous matter containing carbyne nanodomains (the sp hybridised carbon chains) or targets of C₆₀ photopolymer produced carbon clusters which have been detected by FT-ICR (Fourier-Transform Ion Cyclotron Resonance) mass spectrometer. When the carbonaceous matter containing carbyne has been employed as laser target, no C₆₀ has been generated but only fullerene cages from C₇₄ up to C₁₂₄. Larger cages were also obtained but with odd number. Starting from C₆₀ photopolymer, laser ablation regenerates free C₆₀ and creates a sequence of C₆₀ superior homologues all possessing even number and each member of the series is separated from the preceding and the following member by the loss or by the addition respectively of a C₂ unit. Fullerenes up to C₁₆₂ have been recorded. The implications about the presence of free C₆₀ fullerene in the interstellar and circumstellar space, its formation from carbyne chains and its stability towards its photopolymerization tendency and its regeneration from the photopolymer together with its superior homologues have been discussed thoroughly in the present paper.     

Lepidocrocite-like TiO2 and TiO2(110)–(1 × 2) supported on W(100)

Ultrathin films of TiO₂ were grown on a W(100)–O(2?×?1) substrate and characterised with a combination of scanning tunneling microscopy (STM) and low energy electron diffraction. In addition to islands of rutile TiO₂(110) with (1?×?1) termination that were reported previously, we also observed rutile TiO₂(110) islands with a (1?×?2) film termination. A lepidocrocite-like TiO₂ nanosheet was also observed on the W(100) surface. High resolution STM images show that the nanosheet grows in the principal orthogonal directions of the W(100) substrate and forms a commensurate (1?×?7) coincident cell.     

Monte Carlo simulation of the growth of SrTiO3 thin film with molecular source

A three-dimensional model of SrTiO₃ thin film growth under ultraslow growth rate was proposed based on Monte Carlo method. The model is based on Solid on Solid (SOS) model with periodic boundary condition. The ideal molecular source is regarded as a mixture of predominantly SrTiO₃ molecules and a few SrO and TiO₂ molecules. Monte Carlo events consist of deposition, diffusion of molecules and generation of SrTiO₃ molecules. The results show that in the temperature range simulated, the binding possibility of SrO and TiO₂ to SrTiO₃ increases with the increase of the substrate temperature, resulting in the decrease of the number of SrO and TiO₂ molecules. When the substrates temperature reaches a special value (<800 K), all SrO and TiO₂ molecules may already convert to SrTiO₃, which agrees with our previous experiment. Thus, under ultraslow deposition rate and at the temperature beyond 800 K, a simplified Monte Carlo model consisting only of SrTiO₃ cell diffusion can be achieved. The dependence of morphology on the temperature is simulated and the results show that under ultraslow deposition rate, the SrTiO₃ thin film grows with layer-by-layer mode at higher temperature and with island mode at lower temperature, which is qualitatively consistent with the experiment.     

Reactions of microcrystalline fullerene C60 with amino and aza macrocyclic ligands under solvent-free conditions

We evaluated the reactivity under solvent-free conditions of 2-aminomethyl-15-crown-5 (AM15C5), 2-aminomethyl-18-crown-6 (AM18C6), 1,4,8,12-tetraazacyclopentadecane (TACPD) and rac-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane (tet b) with microcrystalline fullerene C₆₀. The reactions of nucleophilic addition were carried out at temperatures of about 160°C for 5 h in the case of crown ethers and TACPD, and at 180–190°C for 24 h in the case of tet b. Characterization of the products obtained was performed by using Fourier-transform infrared (FTIR) and Raman spectroscopy, laser desorption/ionization time-of-flight (LDI-TOF) mass spectroscopy, scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). To provide an additional insight into the reactivity of macrocyclic compounds with C₆₀ molecules, we employed theoretical calculations in the frame of density functional theory (DFT). According to the results of SEM imaging, macrocyclic reagents are generally unable to deeply penetrate into the bulk of fullerene microcrystals (with a possible exception of TACPD). According to TGA measurements, the reaction efficiency is very low for tet b, whereas the average content of organic fraction in C₆₀-AM15C5 and C₆₀-AM18C6 reaches about 29%, and in C₆₀-TACPD, almost 40%. According to LDI-TOF mass spectral analysis, the products of TACPD, tet b and AM15C5 reactions with fullerene have oligomeric or polymeric structure. By using DFT theoretical calculations, the latter observation was explained by enhanced reactivity of secondary amino groups toward nucleophilic addition onto fullerene cage.     

XPS characterization of MWCNT and C60-based composites

X-ray photoelectron spectroscopy was used for characterization of MWNT-C₆₀ composites with assistance of scanning and transmission electron microscopy. The composites were received by immerison of nanotubes into fullerene solution in CS₂ with consequent processing with green laser irradiation at aproximately 10 W/cm². It was shown that C1s spectra of composites are different from simple addition of MWNT and C₆₀ features. It found that preliminary nanotube purification by oxidative treatment influences strongly the nature of fullerene-nanotube bonding. Hydrophilic surface of oxidized nanotube material has lower affinity to C₆₀ molecules and provides for concentration of C₆₀ molecules into clusters, which show differential charging effect in XPS spectra. The differential charging effect disappears after laser processing, which induces photopolymerization of fullerene clusters. The as-synthesized nanotubes form composites with more evenly distributed fullerene.     

Facile and scalable synthesis of a highly hydroxylated water-soluble fullerenol as a single nanoparticle

A water-soluble polyhydroxylated fullerene, i.e. a fullerenol, with 44 hydroxyl groups and 8 secondary bound water molecules, C₆₀(OH)₄₄·8H₂O (estimated average structure), has been synthesized in a facile one step reaction from pristine C₆₀ by hydroxylation with hydrogen peroxide in the presence of a phase-transfer catalyst, tetra-n-butylammonium hydroxide (TBAH), under organic/aqueous bilayer conditions. The fullerenol exhibited high water solubility, up to 64.9 mg/mL, under neutral (pH = 7) conditions. Dynamic light-scattering (DLS) analysis showed a narrow particle size distribution, of 1–2 nm, indicating that the fullerenol had high dispersion properties in water. The results of particle size analyses, which both focused on a single nanoregion and were conducted using a novel induced grating (IG) method and a scanning probe microscope (SPM), were consistent with the DLS results. A plausible reaction mechanism, which includes fullerene oxide intermediates detected by liquid chromatography-mass spectrometry (LC-MS), has been proposed.     

Structural and photocatalytic properties of TiO2/SiOx/TiOx multi-layer prepared by electron-beam evaporation method

TiO₂/SiO_x/TiO_x multi-layers on quartz glass were prepared by electron-beam evaporation method and their structural and photocatalytic properties were investigated. The photocatalytic activity of the TiO₂/SiO_x/TiO_x multi-layer was evaluated by the photodecomposition of methylene blue in aqueous solution. As the thickness of the SiO_x inter-layer increased, the surface roughness of the TiO₂/SiO_x/TiO_x multi-layer increased but the anatase crystallite size decreased. The TiO₂/SiO_x(80 nm)/TiO_x multi-layer exhibited excellent photocatalytic activity resulting from higher surface roughness and more trap levels in the SiO_x(80 nm) inter-layer.     

First synthesis of a new fullerene oximes bis(9-[hydroxo]-1-[1′-hydroxymino-2′-oxo-2′-alkyl-ethyl])1,9-dihydro-[C60-Ih][5,6]fullerenes via reaction of C60 with ketones and NaNO2 promoted by HCl

A mixture of cis-2 and cis-3 isomers of new fullerene derivatives bis(9-[hydroxo]-1-[1′-hydroxymino-2′-oxo-2′-alkyl-ethyl])-1,9-dihydro-[C₆₀-I_h][5,6]fullerenes have been selectively synthesized with high yields at the reaction of C₆₀ fullerene with ketones Me₂CO, EtMeCO, i-PrMeCO, PhMeCO in the presence of NaNO₂ and HCl.     

Zr55Al10Ni5Cu30非晶合金晶化相转变的价电子结构分析

基于EET理论,计算了F-Zr₂(Ni,Cu)和tI-Zr₂Cu及tI-Zr₂(Cu,Ni)相的价电子结构,用最强键键合力n₁、结构单元总成键能力F和单位成键能力F_v分析了F-Zr₂Ni亚稳相向tI-Zr₂Cu型稳定相的转变过程。研究发现:F-Zr₂Ni的n^{F-Zr₂Ni₁值比tI-Zr₂Cu的ntI-Zr₂Cu₁值大115.36%,FF-Zr₂Ni_v值比tI-Zr₂Cu的FtI-Zr₂Cu_v值大34.03%;F-Zr₂(Ni0.3,Cu0.7)的nF-Zr₂(Ni0.3,Cu0.7)₁值比tI-Zr₂Cu的ntI-Zr₂Cu₁值大0.36%,FF-Zr₂(Ni0.3,Cu0.7)_v值比tI-Zr₂Cu的FF-Zr₂Ni}_v值大1.25%; tI-Zr₂(Cu0.6,Ni0.4)的n^{tI-Zr₂(Cu0.6,Ni0.4)₁值比F-Zr₂(Ni0.3,Cu0.7)的nF-Zr₂(Ni0.3,Cu0.7)}₁值大12.95%, F^{tI-Zr₂(Cu0.6,Ni0.4)_v值比F-Zr₂(Ni0.3,Cu0.7)的FF-Zr₂(Ni0.3,Cu0.7)}_v值大14.41%; 从价电子结构角度看,F-Zr₂Ni不能直接转变为tI-Zr₂Cu,F-Zr₂(Ni,Cu)不易分解重构为tI-Zr₂Cu;F-Zr₂(Ni0.3,Cu0.7)可分解并转变为tI-Zr₂(Cu0.6,Ni0.4)。     

The optical properties of nanoporous structured titanium dioxide and the photovoltaic efficiency on DSSC

This study examined the characterization of nanoporous structured titanium dioxide and its application to dye-sensitized solar cells (DSSCs). TEM revealed nanopore sizes of 10.0 nm with a regular hexagonal form. When nanoporous structured TiO₂ was applied to DSSC, the energy conversion efficiency was enhanced considerably compared with that using nanometer sized TiO₂ prepared using a hydrothermal method. The energy conversion efficiency of the DSSC prepared from nanoporous structured TiO₂ was approximately 8.71% with the N719 dye under 100 mW cm⁻² simulated light. FT-IR spectroscopy showed that the dye molecules were attached perfectly to the surface and more dye molecules were absorbed on the nanoporous structured TiO₂ than on the nano-sized TiO₂ particles prepared using a conventional hydrothermal method. Electrostatic force microscopy (EFM) showed that the electrons were transferred rapidly to the surface of the nanoporous structured TiO₂ film.     

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.     

Preparation,characterization, and photocatalytic properties of composite materials of copper(II) porphyrin/TiO2

Three new CuPp–TiO₂ composite materials were prepared by impregnating copper(II) porphyrin with different peripheral substituent (–OH, –COOC₂H₅, and –COOH) onto the surface of polycrystalline TiO₂ at room temperature and characterized by SEM, energy-dispersive X-ray spectrometry, X-ray diffraction, FT-IR, UV–Vis DRS, and photoluminescence. The effects of metalloporphyrins on the surface of TiO₂ have been detected by the photodegradation of 4-nitrophenol (4-NP) and rhodamine B (RhB). The loading of metalloporphyrins onto TiO₂ results in strong visible light absorption by the composite and, more importantly, a 1.47–2.47 times increase in visible light photocatalytic activity in the degradation of RhB. The metalloporphyrins dispersed on the TiO₂ surface can act as a small-band-gap semiconductor to absorb visible light, giving rise to electron–hole separation. What’s more, these CuPp–TiO₂ with different peripheral substituent (–OH, –COOC₂H₅, and –COOH) in meso-sites of porphyrin ring displayed different catalytic activities in the degradation of 4-NP and RhB, the CuPp containing –OH and –COOH showed better catalytic activity due to their strong interaction with TiO₂. A possible mechanism of these higher photocatalytic efficiencies was proposed based on the relative experiments.     

Photovoltaic properties of bulk heterojunction solar cells with improved spectral coverage

The potential of dye sensitization of organic solar cells has been investigated. The electrical and photoelectrical properties of such devices have been studied. The architecture of the solar cell is based on spin-coated thin films of MEH-PPV sensitized with Hydrogen Phthalocyanine (PcH₂) and Coumarin 343 dyes, which are sandwiched between indium tin oxide (ITO)-coated glass and aluminium electrodes. By adding PcH₂ and Coumarin 343 to the MEH-PPV active layer the width of absorption spectrum increases drastically. Introduction of a methine unit (–CHCH–) connecting the cyano (–CN) and carboxyl (–COOH) groups into the Coumarin 343 framework expanded the π — conjugated in the dye and thus resulted in a wide absorption in the visible region. The sensitization of the MEH-PPV thin film by PcH₂ and Coumarin 343 dyes leads to photoluminescence (PL) enhancement whereas the incorporation of fullerene molecules (C₆₀) in the blend, acting as electron acceptors, induces PL quenching due to the separation of the photogenerated charges. Photocurrent enhancement and increase of the open circuit voltage are induced by dye sensitization of MEH-PPV/C₆₀ blends.     

Fabrication of dye-sensitized solar cells using TiO2-nanotube arrays on Ti-grid substrates

Self-aligned TiO₂ nanotube arrays (20 μm in length) were fabricated by anodic oxidation of Ti-grid with a thickness of 100 μm in an ethylene glycol electrolyte with an addition of H₂O (1.5 vol.%) and NH₄F (0.2 wt.%). Voltage applied between Ti and Pt cathodes is 60 V at ~ 22 °C. Dye-sensitized solar cell utilizing photoanode structure of TiO₂-nanotube/Ti-grid was fabricated with no transparent conducting oxide (TCO) layer, in which Ti-grid replaces TCO. Overall photoconversion efficiency is very low (< 0.5%) due to the large pore size (100 nm in diameter) of the nanotubes, which may cause insufficient dye molecules to be attached, thus limiting light harvesting.