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An in situ spectroelectrochemical study of the oxidation of the μ-oxosilicon phthalocyanine dimer [(SiPc)2O][OSiHx3]2 utilizing cyclic voltammetry, electron spin resonance spectroscopy, and visible–near infrared spectroscopy has been carried out. The results of this study show that oxidation of the dimer yields the paramagnetic radical dimer [(SiPc)2O][OSiHx3]2·+ and then the diamagnetic dimer [(SiPc)2O][OSiHx3]22+. The study shows that the rings of [(SiPc)2O][OSiHx3]22+ are antiferromagnetically coupled.

Among the applications of fullerene technology in health sciences the expanding field of magnetic resonance imaging (MRI) of molecular processes is most challenging. Here we present the synthesis and application of a GdxSc3-xN@C80-BioShuttle-conjugate referred to as Gd-cluster@-BioShuttle, which features high proton relaxation and, in comparison to the commonly used contrast agents, high signal enhancement at very low Gd concentrations. This modularly designed contrast agent represents a new tool for improved monitoring and evaluation of interventions at the gene transcription level. Also, a widespread monitoring to track individual cells is possible, as well as sensing of microenvironments. Furthermore, BioShuttle can also deliver constructs for transfection or active pharmaceutical ingredients, and scaffolding for incorporation with the host's body. Using the Gd-cluster@-BioShuttle as MRI contrast agent allows an improved evaluation of radio- or chemotherapy treated tissues.

The synthesis of a novel alkali-metal aluminium borohydride NaAl(BH4)xCl4−xfrom NaBH4and AlCl3using a solid state metathesis reaction is described. Structure determination was carried out using synchrotron powder diffraction data and vibrational spectroscopy. An orthorhombic structure (space group Pmn21) is formed which contains Na+cations and complex [Al(BH4,Cl)4]−anions. Due to the high chlorine content (1 ≤ x≤ 1.43) the hydrogen density of the borohydride is only between 2.3 and 3.5 wt.% H2in contrast to the expected 14.6 wt.% for chlorine free NaAl(BH4)4. The decomposition of NaAl(BH4)xCl4−xis observed in the target range for desorption at about 90 °C by differential scanning calorimetry (DSC), in situRaman spectroscopy and synchrotron powder X-ray diffraction. Thermogravimetric analysis (TG) shows extensive mass loss indicating the loss of H2and B2H6at about 90 °C followed by extensive weight loss in the form of chloride evaporation. [ABSTRACT FROM AUTHOR]

The row of endohedral fullerenes is extended by a new type of sulfur-containing clusterfullerenes: the metal sulfide (M2S) has been stabilized within a fullerene cage for the first time. The new sulfur-containing clusterfullerenes M2S@C82-C3v(8) have been isolated for a variety of metals (M = Sc, Y, Dy, and Lu). The UV-vis-NIR, electrochemical, and FTIR spectroscopic characterization and extended DFT calculations point to a close similarity of the M2S@C82 cage isomeric and electronic structure to that of the carbide clusterfullerenes M2C2@C2n. The bonding in M2S@C82 is studied in detail by molecular orbital analysis as well as with the use of quantum theory of atom-in-molecules (QTAIM) and electron localization function (ELF) approaches. The metal sulfide cluster formally transfers four electrons to the carbon cage, and metal-sulfur and metal-carbon cage bonds with a high degree of covalency are formed. Molecular dynamics simulations show that Sc2S cluster exhibits an almost free rotation around the C3 axis of the carbon cage, resulting thus in a single line 45Sc NMR spectrum. [ABSTRACT FROM AUTHOR]

The electrochemical oxidation of the chemically prepared polymer poly[2-(3-thienyl)ethyl acetate] (PTEtAc), its partially hydrolyzed derivative PTEtAcOH and the fully hydrolyzed compound poly[2-(3-thienyl)ethanol] (PTEtOH) was studied by in situelectron spin resonance (ESR)/UV-Vis-NIR spectroelectrochemistry. The spectroelectrochemical response of these films on ITO substrates was analyzed with respect to the influence of the functionalized alkyl side chain on polymer doping. The simultaneous use of both electron spin resonance and UV-Vis-NIR spectroscopy allows the analysis of the nature, extent and stability of the charge carriers electrogenerated during p-doping. It was found that PTEtAc has a higher capacity for charged species due to the flexibility of the longer side chains making the redox states more stable at different doping levels. At low doping levels the charged states are dominated by polaronic species while at high doping levels bipolarons and diamagnetic polaron pairs are formed. The presence of the OH groups in the polymer side chains of the hydrolyzed derivatives favors hydrogen bonds. These interactions by hydrogen bonding fix the conjugated chains thus making a charge–discharge reaction more difficult. At high doping levels the hydrolyzed polymers favor the formation of polaron pairs. [ABSTRACT FROM AUTHOR]

Abstract  A detailed study is presented on the optical absorption of thin films of single-walled carbon nanotubes (SWNT) under electrochemical conditions. The procedure for the preparation of free-standing semitransparent films of SWNT is used for the fabrication of a working electrode for transmission optical spectroelectrochemistry. The analysis of the potential dependent spectroscopic response of the SWNT film benefits from the widest possible electrochemical window, in which the charging of SWNT can safely be investigated. This electrochemical window is not limited by parasitic electrochemistry and/or galvanic breakdown reactions occurring at supporting electrode materials such as indium–tin oxide conducting glass or semitransparent Pt film, which were employed in earlier studies. Electrochemical doping of SWNT is observable at the optical absorptions, which are assigned to allowed electronic transitions between van Hove singularities in the density of states of SWNT. Furthermore, the spectral response of counterions, balancing the charging of the nanotube skeleton, is traceable at certain conditions. The latter effect is monitored here through the overtones of C–H stretching vibrations from tetrabutylammonium cations. [ABSTRACT FROM AUTHOR]

A series of 2-diarylaminothiophene-based starburst compounds 14–16 with a central triphenylamino-, benzene-, and 1,3,5-triphenylbenzene moiety, respectively, were prepared at moderate yields by a palladium-catalysed coupling reaction. Their electrochemical, optical and magnetic properties were studied with respect to their application as hole transport materials, using cyclic voltammetry and in situ ESR-UV/Vis/NIR spectroelectrochemistry. Although all prepared 2-diarylaminothiophene-based starburst compounds are structurally related, their electrochemical properties differ in their dependence on the central moiety. The number of reversible voltammetric peaks is diminished upon changing the central triphenylamino moiety of the starburst compounds to a central benzene or 1,3,5-triphenylbenzene moiety. The simultaneous multiple electron transfer as well as the location of the spins on the core moieties was detected in the oxidation of the 1,3,5-triphenylbenzene based starburst compound. The stability of the charged states increased substantially upon the incorporation of a thiophene moiety between the central moieties and the side groups. [ABSTRACT FROM AUTHOR]

The family of endohedral fullerenes was significantly enlarged within the past six years by the clusterfullerenes containing structures like the M2C2 carbides and the M3N nitrides. While the carbide clusters are generated under the standard arc burning conditions according to the stabilisation energy the nitride clusterfullerene type is formed by varying the composition of the cooling gas atmosphere in the arc burning process. The special situation in nitride clusterfullerene synthesis is described in detail and the optimum conditions for the production of nitride clusterfullerenes as the main product in fullerene synthesis are discussed. A review of new nitride clusterfullerenes reported recently is given summarizing the structures, properties and the stability of metal nitride clusterfullerenes. It is shown that all cages with even carbon atoms of C68 and beyond are available as endohedral nitride clusterstructures. Furthermore the nitride clusterfullerenes are that class of endohedral fullerenes forming the largest number of non-IPR structures. Finally the prospects of this evolving field are briefly discussed taking the superior stability of these endohedral clusterfullerenes into account. [ABSTRACT FROM AUTHOR]

High-temperature syntheses of the new C60(i-C3F7)2,4,6and C70(i-C3F7)2,4isomers and their characterization by spectroscopic methods, X-ray crystallography, cyclic voltammetry and density functional theory provide compelling evidence that they are superior electron acceptors than trifluoromethylfullerenes. [ABSTRACT FROM AUTHOR]

With the successful isolation of TiSc2N@C80, the first Ti-containing nitride clusterfullerene (NCF), a non-group-III metal is stabilized in a NCF for the first time. [ABSTRACT FROM AUTHOR]

Three novel C68-based mixed metal nitride clusterfullerenes, which comprise of a small non-IPR C68 cage encapsulating large nitride clusters including DySc2N, LuSc2N, and Lu2ScN, have been synthesized and isolated, resulting in overpassing the confinement of the C68 cage. [ABSTRACT FROM AUTHOR]

Although the Gd ion in Gd@C82 has been shown to lie above the C–C bond on the C2 axis as an anomalous structure from the MEM/Rietveld analysis, the present XANES study reveals that it lies above the hexagon on the C2 axis as a normal structure, and Gd oscillates around its equilibrium position with an amplitude increasing with temperature increase. [ABSTRACT FROM AUTHOR]

Raman spectroscopy and in situ Raman spectroelectrochemistry were applied to study the lithium vapor doping of C70@SWCNTs (peapods). A strong degree of doping was proved by the vanishing of the single walled carbon nanotubes (SWCNT’s) radial breathing mode (RBM) and by the attenuation of the tangential (TG) band intensity. In contrast to potassium vapor doping, the strong downshift of the frequency of the TG band has not been observed for Li-doping. The Li vapor treated peapods remained partly doped even if they were exposed to humid air. This has been reflected by a reduced intensity of the nanotube and the fullerene modes and by the change of the shape of the RBM band as compared to that of the undoped sample. The modes of the intratubular fullerene were almost unresolved after the contact of the Li-doped sample with water. A lithium insertion into the interior of a peapod and its strong interaction with the intratubular fullerene is suggested to be responsible for the air-insensitive residual doping. This residual doping was studied by spectroelectrochemical measurements. The TG band of the Li doped peapods is partly upshifted during the anodic doping, which points to the different state of C70@SWCNTs and C60@SWCNTs studied previously. [ABSTRACT FROM AUTHOR]

Unconventional fullerenes are those smaller than C60 or those intermediate between C60 and C70, which are not stable in structure as none of the unconventional fullerene isomers satisfying the "isolated- pentagon-rule" (IPR). Below we report the synthesis of a stable unconventional fullerene derivative C64H4 by introducing methane in the fullerene productions with the normal Krätschmer-Huffman method. We also applied various spectroscopic measurements such as mass spectrometry, 13C NMR, IA, UV-vis absorption spectrometry, etc. to characterize the structural and electronic properties of this molecule, revealing an unprecedented fullerene cage with a triplet of directly fused pentagons in the framework of C64H4. Four hydrogen atoms are added to the carbons at vertexes of fused pentagons to allow the bond angles at these sites close to the sp³ tetrahedral angle, which essentially release the sp² bond strains on the abutting-pentagon sites of C64. Ab initio calculations were performed to explore the electronic property and simulate the 13C NMR and lR spectra of this fulleride, which reproduced well the experimental results and confirmed the structural assignment of the C64H4. [ABSTRACT FROM AUTHOR]