Organo-Zintl clusters soluble in conventional organic solvents: setting the stage for organo-Zintl cluster chemistry

Organo-Zintl cluster ions were synthesized by reactions of alkynes with Ge94- clusters in ethylenediamine. The triple bonds are hydrogenated to double bonds during the process. The resulting dial-kenylated species [RHC=CHGe9CH=CHR]2- have lower charge, their alkali-metal cations can be exchanged for tetralkylammonium cations, and the resulting compounds are soluble in nonpolar solvents. This was demonstrated with [H2C=CHGe9CH=CH2]2-, which was structurally characterized with [K-(18-crown-6)]+, [Me4N]+, and [Pr4N]+ as countercations. The solubility of its salt with [Oc4N]+ in various conventional organic solvents was studied.     

Tracking and controlling everything that affects quality is the key to a quality management system

Every laboratory has a need to track and control the variables that drive the quality of the results. However, each laboratory is unique and what one organization deems to be a critical process to track and control will likely differ from other organizations. Furthermore, there is more than just the end product or result that needs to be tracked and controlled. All of the intermediate products and resources play a significant role in producing the final product and each of these needs to be included in the LIMS. At a high level, this article will present ideas and opinions on the following topics in relation to implementing a LIMS process tracking and control system in a laboratory: The difference between tracking and controlling processes; What to track and control in the lab; The "product" of the laboratory; Preventing mistakes in a laboratory; Comprehensive software platform options; The value of seeing a system as opposed to imagining it; The use of barcodes in the laboratory; and an assessment on using the Risk Based Approach in deciding what to include in the tracking system.     

Thermal variation of structure and electrical conductivity in Bi14WO24

Structure and electrical conductivity of Bi₁₄WO₂₄ as a function of temperature have been examined by X-ray and neutron powder diffraction, a.c. impedance spectroscopy and differential thermal analysis. The room temperature structure was successfully refined using a monoclinic subcell model in space group I2/m. However, additional reflections in the neutron data are consistent with a large supercell of dimensions a = 17.3780(1) Å, b = 17.3891(1) Å, c = 26.1785(2) Å and β = 90.270(1)°, as previously proposed. Transitions to tetragonal and cubic phases are observed at ca. 35 °C and 780 °C, respectively. The structure of the high temperature polymorph is confirmed as a fully disordered δ-Bi₂O₃ type phase. Analysis of the defect structure is consistent with a predominantly tetrahedral environment for tungsten, as seen at low temperatures. The conductivity behaviour is correlated with the appearance of the δ-phase at high temperatures and exhibits a value of 0.97 S cm^− 1 at 800 °C.     

High-pressure structural and vibrational study of PbZr0.40Ti0.60O3

The high-pressure structure and dynamics of PbZr0.40Ti0.60O3 were investigated by means of neutron diffraction, X-ray diffraction, and resonance Raman spectroscopy. The complex (P4mm, Cm, Cc, F1, F1) phase transition sequence is characterized by these techniques. On the basis of the results of structure refinements, the high-pressure behavior of the spontaneous polarization, the (Zr,Ti)O6 rotation angles, and the polarization rotation angle are obtained. Moreover, resonance Raman spectra combined with previous Raman data in the literature provide evidence that the pressure-induced transition to the monoclinic Cm space group and the above transition sequence terminating in a paraelectric state are general features of Pb(Zr(1-x)Ti(x))O3 (0.48 < or = x < or = 1).     

Highly regioselective catalytic oxidative coupling reactions: synthetic and mechanistic investigations

A highly efficient and regioselective Pd-catalyzed method for the oxidative coupling of arylpyridine derivatives is reported. Remarkably, the reactions proceed at room temperature and are compatible with diverse functionalities, including aryl halides and thiophenes. Mechanistic studies suggest that these transformations proceed via a previously unprecedented mechanism involving two different pyridine-directed C-H activation reactions-one at a PdII center and one at PdIV.