Synthesis of 2D Germanane (GeH): a New,Fast, and Facile Approach

Germanane (GeH), a germanium analogue of graphane, has recently attracted considerable interest because its remarkable combination of properties makes it an extremely suitable candidate to be used as 2D material for field effect devices, photovoltaics, and photocatalysis. Up to now, the synthesis of GeH has been conducted by substituting Ca by H in a β‐CaGe₂ layered Zintl phase through topochemical deintercalation in aqueous HCl. This reaction is generally slow and takes place over 6 to 14 days. The new and facile protocol presented here allows to synthesize GeH at room temperature in a significantly shorter time (a few minutes), which renders this method highly attractive for technological applications. The GeH produced with this method is highly pure and has a band gap (E_g) close to 1.4 eV, a lower value than that reported for germanane synthesized using HCl, which is promising for incorporation of GeH in solar cells.     

Solvent-Free Synthesis of Core-Functionalised Naphthalene Diimides by Using a Vibratory Ball Mill: Suzuki,Sonogashira and Buchwald–Hartwig Reactions

Solvent-free synthesis by using a vibratory ball mill (VBM) offers the chance to access new chemical reactivity, whilst reducing solvent waste and minimising reaction times. Herein, we report the core functionalisation of N,N’-bis(2-ethylhexyl)-2,6-dibromo-1,4,5,8-naphthalenetetracarboxylic acid (Br₂-NDI) by using Suzuki, Sonogashira and Buchwald–Hartwig coupling reactions. The products of these reactions are important building blocks in many areas of organic electronics including organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs) and organic photovoltaic cells (OPVCs). The reactions proceed in as little as 1 h, use commercially available palladium sources (frequently Pd(OAc)₂) and are tolerant to air and atmospheric moisture. Furthermore, the real-world potential of this green VBM protocol is demonstrated by the double Suzuki coupling of a monobromo(NDI) residue to a bis(thiophene) pinacol ester. The resulting dimeric NDI species has been demonstrated to behave as an electron acceptor in functioning OPVCs.     

The Ideal Ionic Liquid Salt Bridge for the Direct Determination of Gibbs Energies of Transfer of Single Ions,Part I: The Concept

Described is a procedure for the thermodynamically rigorous, experimental determination of the Gibbs energy of transfer of single ions between solvents. The method is based on potential difference measurements between two electrochemical half cells with different solvents connected by an ideal ionic liquid salt bridge (ILSB). Discussed are the specific requirements for the IL with regard to the procedure, thus ensuring that the liquid junction potentials (LJP) at both ends of the ILSB are mostly canceled. The remaining parts of the LJPs can be determined by separate electromotive force measurements. No extra‐thermodynamic assumptions are necessary for this procedure. The accuracy of the measurements depends, amongst others, on the ideality of the IL used, as shown in our companion paper Part II.     

Probing the Intracellular Glutathione Redox Potential by In‐Cell NMR Spectroscopy

Non‐invasive and real‐time analysis of cellular redox processes has been greatly hampered by lack of suitable measurement techniques. Here we describe an in‐cell nuclear magnetic resonance (NMR) based method for measuring the intracellular glutathione redox potential by direct and quantitative measurement of isotopically labeled glutathione introduced exogenously into living yeast. By using this approach, perturbations in the cellular glutathione redox homeostasis were also monitored as yeast cells were subjected to oxidative stress.     

Apoptolidin: induction of apoptosis by a natural product

Apoptolidin is a natural product that selectively induces apoptosis in several cancer cell lines. Apoptosis, programmed cell death, is a biological key pathway for regulating homeostasis and morphogenesis. Apoptotic misregulations are connected with several diseases, in particular cancer. The extrinsic way to apoptosis leads through death ligands and death receptors to the activiation of the caspase cascade, which results in proteolytic degradation of the cell architecture. The intrinsic pathway transmits signals of internal cellular damage to the mitochondrion, which loses its structural integrity, and forms an apoptosome that initiates the caspase cascade. Compounds which regulate apoptosis are of high medical significance. Many natural products regulate apoptotic pathways, and apoptolidin is one of them. The known synthetic routes to apoptolidin are described and compared in this Review. Selected further natural products which regulate apoptosis are introduced briefly.     

Quantification of particle-bubble interactions using atomic force microscopy: A review

The attachment of particles to bubbles in solution is of fundamental importance to several industrial processes, most notably in the process of froth flotation. During this process hydrophobic particles attach to air bubbles in solution, which allows them to be separated as froth at the surface. The addition of chemicals can help to modulate these interactions to increase the yield of the minerals of interest. Over the past decade the atomic force microscope (AFM) has been adapted for use in studying the forces involved in the attachment of single particles to bubbles in the laboratory. This allows the measurement of actual DLVO (Derjaguin, Landau, Vervey and Overbeek) forces and adhesive contacts to be measured under different conditions. In addition contact angles may be calculated from features of force versus distance curves. It is the purpose of this article to illustrate how the colloid probe technique can be used to make single particle-bubble interactions and to summarise the current literature describing such experiments.     

Determination of sulfur and selected trace elements in metallothionein-like proteins using capillary electrophoresis hyphenated to inductively coupled plasma mass spectrometry with an octopole reaction cell

The determination of sulfur in biologically relevant samples such as metalloproteins is described. The analytical methodology used is based on robust on-line coupling between capillary electrophoresis (CE) and octopole reaction cell inductively-coupled plasma mass spectrometry (ORC–ICP–MS). Polyatomic ions that form in the plasma and interfere with the determination of S at mass 32 are minimised by addition of xenon to the collision cell. The method has been applied to the separation and simultaneous element-specific detection of sulfur, cadmium, copper, and zinc in commercially available metallothionein preparations (MT) and metallothionein-like proteins (MLP) extracted from liver samples of bream (Abramis brama L.) caught in the river Elbe, Germany. Instrumental detection limits have been calculated according to the German standard procedure DIN 32645 for the determination of sulfur and some simultaneously measured trace elements in aqueous solution. For sulfur detection limits down to 1.3 g L^–1 (³⁴S) and 3.2 g L^–1 (³²S) were derived. For the other trace elements determined simultaneously detection limits ranging from 300 ng L^–1 (⁵⁸Ni) to 500 ng L^–1 (⁶⁶Zn, ⁵⁵Mn) were achieved. For quantification of sulfur and cadmium in a commercially available MT preparation under hyphenated conditions the use of external calibration is suggested. Finally, the need for proper sample-preparation technique will be discussed.     

Reducing methane formation in methanol to olefins reaction on metal impregnated SAPO-34 molecular sieve

SAPO-34 silicoaluminophosphate molecular sieve produces large amounts of methane at elevated temperatures in the methanol to olefins (MTO) process. This significantly reduces the lower olefins selectivity a key factor in determining the commercial viability of this catalyst. Impregnation of the SAPO-34 molecular sieve with metal ions such as K, Cs, Pt, Ag and Ce was found to reduce the amount of methane significantly at higher temperatures thereby increasing the lower olefins selectivity. This observed effect is less apparent at lower temperatures where the amount of methane formed is generally low. This revised version was published online in June 2006 with corrections to the Cover Date.     

Multi-scale magnetic resonance measurements and validation of Discrete Element Model simulations

This short review describes the capabilities of magnetic resonance (MR) to image opaque single- and two-phase granular systems, such as rotating cylinders and gas-fluidized beds operated in different fluidization regimes. The unique capability of MR to not only image the solids’ distribution (voidage) but also the velocity of the particulate phase is clearly shown. It is demonstrated that MR can provide measurements over different length and time scales. With the MR equipment used for the studies summarized here, temporal and spatial scales range from sub-millisecond to hours and from a few hundred micrometres to a few centimetres, respectively. Besides providing crucial data required for an improved understanding of the underlying physics of granular flows, multi-scale MR measurements were also used to validate numerical simulations of granular systems. It is shown that predictions of time-averaged properties, such as voidage and velocity of the particulate phase, made using the Discrete Element Model agree very well with MR measurements.