Reducing HAuCl4 by the C-60 dianion: C-60-directed self-assembly of gold nanoparticles into novel fullerene bound gold nanoassemblies

The C-60 dianion is used to reduce tetrachloroauric acid (HAuCl4) for the first time; three-dimensional C-60 bound gold (Au-C-60) nanoclusters are obtained from C-60-directed self-assembly of gold nanoparticles due to the strong affinities of Au-C-60 and C-60-C-60. The process was monitored in situ by UV-vis-NIR spectroscopy. The resulting Au-C-60 nanoclusters were characterized using transmission electron microscopy (TEM), selected area electron diffraction (SAED), energy-dispersive spectroscopy (EDS), x-ray powder diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and FT-IR and Raman spectroscopies.

Effects of fullerene solubility on the crystallization of poly(3-hexylthiophene) and performance of photovoltaic devices

The substantial crystallization suppression of poly(3-hexylthiophene) (P3HT) in the untreated P3HT:C60 composite film prepared from o-dichlorobenzene (ODCB) solution has been revealed. Besides, the effective conjugation length of P3HT in this composite has been nearly maintained to that in the solution. The different crystallization behaviors of P3HT in its composites with C60 and [6,6]-phenyl C-61 butyric acid methyl ester (PCBM) are mainly attributed to the relative solubility of C60 and PCBM with respect to P3HT in ODCB. The solution to overcome this disadvantage of chain conformation and crystallinity of P3HT in the composite with C60 is thus proposed and finalized by resorting to the addition of low volatile solvent with much higher solubility of C60 than P3HT into the main solvent used, so as P3HT can crystallize before C60 forms crystallites in the solution. The feasibility of this approach has been proven by the improved efficiency of devices based on composites of P3HT and the low cost C60 without resorting to post-treatments.

Investigation of ion transfer across the micro-water/nitrobenzene interface facilitated by a fullerene derivative

A functionalized fullerene derivative containing a monoaza-18-crown-6 moiety was investigated by facilitated ion (such as Li+, Na+, K+, NH4+, Mg2+, and Ca2+) transfer across the micro-water/nitrobenzene interface supported at the tip of a micropipet. The current responses were detected by cyclic voltammetry and Osteryoung square wave voltammetry, which demonstrated that the facilitated ion transfer does occur by an interfacial complexation-dissociation process. The diffusion coefficient of this compound in nitrobenzene was approximately (5.90 +/- 0.04) x 10(-7) cm(2) s(-1), which is 1 order of magnitude less than other common ionophores due to the large size of the molecule. The selectivity of this molecule toward the metal ions followed the sequence Na+ > Li+ > K+ > NH4+ > Ca2+ similar to Mg2+. In addition, this compound was also easy to form film at the water/nitrobenzene interface to inhibit the simple ion transfer of tetramethylammonium ion. However, the adsorption of this ionophore has less influence on the facilitated metal ion transfer.

Synthesis and spectroscopic studies of endohedral metallofullerenes Tb@C-2n

Endohedral metallofullerenes Tb@C-2n were synthesized and extracted with high-yield by K-H carbon-are evaporation and an effective pyridine extraction technique at high-temperature high-pressure. Laser-desorption-ionization time-of-flight (LD-TOF) mass spectrometry, X-ray photoelectron spectroscopy (XPS), solid-state fluorescent emission spectroscopy and gas phase derivation reaction with the self-chemical ionization mass spectrometric ion system of vinyl acetate were employed for studying the electronic structures, fluorescent properties and gas phase reactivities of metallofullerenes Tb@C-2n. The experimental results suggest that endohedral metallofullerenes Tb@C-2n would have the approximate structures of Tb3+@C-2n(3-) similar to other metallofullerenes, good fluorescent emission properties and active reactivities in gas phase ion-molecular reactions.

High-temperature, high-pressure extraction of metallofullerenes Gd@C-2n

A high-temperature, high-pressure extraction technique with toluene and pyridine were employed for the extraction of metallofullerenes Gd@C-2n, A series of Gd@C-2n for 2n from 70 to 96 were effectively extracted by toluene. Gd@C-74 was shown to be a new stable soluble metallofullerene species. Pyridine was found to be more useful for the extraction of Gd@C-82 and Gd-2@C-80 from empty fullerenes and other metallofullerene species.

ELECTROCHEMICAL MECHANISM FOR FULLERENE FORMATION IN PLASMA ARCS

During the synthesis of fullerenes by dc plasma arcs, it has been found that the anodic graphite rod consistently burns up, while the cathodic graphite rod grows slag at its end. Further investigations revealed that the anodic and cathodic graphite rods p

Heterogeneities in fullerene nanoparticle aggregates affecting reactivity, bioactivity, and transport.

Properties of nanomaterial suspensions are typically summarized by average values for the purposes of characterizing these materials and interpreting experimental results. We show in this work that the heterogeneity in aqueous suspensions of fullerene C(60) aggregates (nC(60)) must be taken into account for the purposes of predicting nanomaterial transport, exposure, and biological activity. The production of reactive oxygen species (ROS), microbial inactivation, and the mobility of the aggregates of the nC(60) in a silicate porous medium all increased as suspensions were fractionated to enrich with smaller aggregates by progressive membrane filtration. These size-dependent differences are attributed to an increasing degree of hydroxylation of nC(60) aggregates with decreasing size. As the quantity and influence of these more reactive fractions may increase with time, experiments evaluating fullerene transport and toxicity end points must take into account the evolution and heterogeneity of fullerene suspensions.

Ring-opening polymerisation of silver-diphosphine [M2L3] coordination cages to give [M2L3](infinity) coordination polymers

[M2L3] coordination cages and linear [M2L3]infinity polymers of the rigid, bridging diphosphines bis(diphenylphosphino)acetylene (dppa) and trans-1,2-bis(diphenylphosphino)ethylene (dppet) with silver(I) salts have been investigated in the solution and solid states. Unlike flexible diphosphines, 1:1 dppa/AgX mixtures do not selectively form discrete [Ag2(diphos)2(X)2] macrocycles; instead dynamic mixtures of one-, two- and three-coordinate complexes are formed. However, 3:2 dppa/AgX ratios (X = SbF6. BF4, O3SCF3 or NO3) do lead selectively to new [M2L3] triply bridged cage complexes [Ag2(dppa)3(X)2] 1a-d (X = SbF6 a, BF4 b, O3SCF3 c, NO3 d), which do not exhibit Ag-P bond dissociation at room temperature on the NMR time scale (121 MHz). Complexes la-d were characterised by X-ray crystallography and were found to have small internal cavities, helical conformations and multiple intramolecular aromatic interactions. The nucleophilicity of the anion subtly influences the cage shape: Increasing nucleophilicity from SbF6 (1a) through BF4 (1b) and O3SCF3 (1c) to NO3 (1d) increases the pyramidal distortion at the AgP3 centres, stretching the cage framework (with Ag...Ag distances increasing from 5.48 in 1a to 6.21 A in 1d) and giving thinner internal cavities. Crystal packing strongly affected the size of the helical twist angle, and no correlation between this parameter and the Ag-Ag distance was observed. When crystalline 1c was stored in its supernatant for 16 weeks, conversion occured to the isostoichiometric [M2L3]infinity coordination polymer [Ag(dppa)2Ag(dppa)(O3SCF3)2]infinity (1c'). X-ray crystallography revealed a structure with ten-membered Ag2(dppa)2 rings linked into infinite one-dimensional chains by a third dppa unit. The clear structural relationship between this polymer and the precursor cage 1c suggests a novel example of ring-opening polymerisation. With dppet, evidence for discrete [M2L3] cages was also found in solution, although 31P NMR spectroscopy suggested some Ag-P bond dissociation. On crystallisation, only the corresponding ring-opened polymeric structures [M2L3]infinity could be obtained. This may be because the greater steric bulk of dppet versus dppa destabilises the cage and favours the ring-opening polymerisation.

Ultralow Silicon Substrate Noise Crosstalk Using Metal Faraday Cages in an SOI Technology

In mixed signal integrated circuits noise from the digital circuitry can upset the sensitive analogue circuitry. The Faraday cage structure reported here is based on the unique ground plane SOI technology developed some of the authors. The suppression of crosstalk achieved is an order of magnitude greater than that previously published for frequencies up to 10 GHz. The significance of the technology will be even greater as the operating frequency is increased. This collaborative EPSRC project was judge as tending to outstanding.