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An excess of BuLi in the presence of N,N,N',N'-tetramethylethylenediamine at slightly elevated temperatures is used to dilithiate the homoleptic sandwich complex bis(benzene)molybdenum. The results reveal that isolation of an elusive ansa-bridged derivative is accomplished along with the characterization of a molybdenum-containing paracyclophane complex.

Spinel-type lithium manganese oxides are considered as promising cathode materials for lithium-ion batteries. Trace amounts of Li2MnO3 usually occur as a secondary phase in lithium-manganese spinels in the common high-temperature, solid-state synthesis, affecting the overall Li-Mn stoichiometry in the spinel phase and thereby the electrochemical performance. However, the formation of Li2MnO3 lower than 1 wt.% can hardly be quantified by the conventional analytical techniques. In this work, we synthesized lithium-manganese spinels with different Li/Mn molar ratios and demonstrate that electron paramagnetic resonance (EPR) enables quantifying trace amounts of Li2MnO3 below 10−2 wt.% in the synthesized products. The results reveal that the formation of Li2MnO3 secondary phase is favored by lithium excess in the synthesis. Based on the quantitative evaluation of the EPR data, precise determining Li-Mn stoichiometry in the spinel phase in Li1+xMn2−xO4 materials can be assessed. Accordingly, it is possible to estimate the amount of lithium on 16d-sites in the Li-rich manganese spinels. [ABSTRACT FROM AUTHOR]

We present a detailed structural discussion of [Au8(PPh3)8](NO3)2, crystallized as a CH2Cl2 solvate. Its structure is compared with closely related triphenylphosphine-stabilized gold clusters. Characterization by optical extinction spectroscopy, luminescence spectroscopy, voltammetry and DFT calculations was performed to determine the electronic HOMO-LUMO gap. Comparison of its characteristic energies with those of structurally related clusters revealed that the evolution of the HOMO-LUMO gap does not follow a simple scaling law but depends on specific structural features. [ABSTRACT FROM AUTHOR]

Integration of molecule-capped goldnanoparticles (AuNP) into nanoelectronicdevices requires detailed knowledge about the AuNP–electrodeinterface. Here, we report the pH-dependent adsorption of amine orcarboxylic acid-terminated gold nanoparticles on platinum or gold/palladium(30% Pd) alloy, respectively. We synthesized amine-terminated AuNP,applying a new solid phase supported approach, as well as AuNP exhibitingcarboxylic acid as terminal groups. The pH-induced agglomeration ofthe synthesized AuNP was investigated by UV–vis, DLS, and ζ-potentialmeasurements. Depending on the pH and the ionic strength of the AuNPsolution a preferential adsorption on the different metals occurred.Thereby, we demonstrate that by choosing the appropriate functionalgroup and adjusting the pH as well as the ionic strength a directedbinding can be achieved, which is an essential prerequisite for applicationsof these particles in nanoelectronics. These findings will pave theway for a controlled designing of the interface between molecule-cappedAuNP and metallic electrodes for applications in nanoelectronics. [ABSTRACT FROM AUTHOR]

Electronic transport measurements of single, systematically varied 4,4′-bis(mercaptoalkyl)-biphenyl derivatives (MABP) are performed in a controlled test-device. The molecules are composed of a central biphenyl unit (BP) carrying two mercaptoalkyl substituents with different chain lengths (m, n= number of CH2-units), in the para-position of the BP unit. The total length of both spacers is m+ n= 10. The molecular conductance of these individual MABPs deposited on Au (111) substrates is studied using STM-based break junctions. It is shown that the molecular conductance depends on the relative position of the BP unit within the molecule. In the case of the symmetric derivative 5BP5 a value of 0.07 ± 0.01 nS is obtained, while for 1BP9 the molecular conductance is doubled and a value of 0.17 ± 0.03 nS results. This relatively high value of conductance for the single Au(tip)-1BP9-Au(substrate) junction is attributed to an increased coupling of the BP unit to the adjacent electrode, i.e.the STM-tip or the Au-substrate. We address the role of the specific contact situation (–S–Au) and of the position of the electrically active molecular moiety and thus come to a deeper understanding of the electronic transport properties of 4,4′-bis(mercaptoalkyl)biphenyl derivatives. [ABSTRACT FROM AUTHOR]

We present a detailed structural discussion of [Au8(PPh3)8](NO3)2, crystallized as a CH2Cl2 solvate. Its structure is compared with closely related triphenylphosphine-stabilized gold clusters. Characterization by optical extinction spectroscopy, luminescence spectroscopy, voltammetry and DFT calculations was performed to determine the electronic HOMO-LUMO gap. Comparison of its characteristic energies with those of structurally related clusters revealed that the evolution of the HOMO-LUMO gap does not follow a simple scaling law but depends on specific structural features. [ABSTRACT FROM AUTHOR]

Ligand-stabilized gold nanoparticles (AuNPs) are of high interest to research dedicated to future technologies such as nanoelectronics or biomedical applications. This research interest arises from the unique size-dependent properties such as surface plasmon resonance or Coulomb charging effects. It is shown here how the unique properties of individual AuNPs and AuNP assemblies can be used to create new functional materials for applications in a technical or biological environment. While the term technical environment focuses on the potential use of AuNPs as subunits in nanoelectronic devices, the term biological environment addresses issues of toxicity and novel concepts of controlling biomolecular reactions on the surface of AuNPs.