Syntheses, structures and redox properties of {Os(PPh3)2Cp}2{μ-(CC)x} (x = 2, 3, 4): Comparisons with the Ru analogues

The syntheses of {Os(PPh₃)₂Cp}₂{μ-(CC)_x} (x = 2, 3, 4) from reactions between OsBr(PPh₃)₂Cp* and Me₃Si(CC)_xSiMe₃ in the presence of KF/NaBPh₄ are described. The molecular structure of x = 3 has been determined by a single-crystal XRD study. Comparison of the redox properties of {M(PPh₃)₂Cp}₂{μ-(CC)_x} (M = Ru, Os) shows that the oxidation potentials of the osmium complexes are invariably lower (by between 0.16 and 0.64 V) than those of the Ru analogues.     

Some complexes containing carbon chains end-capped with tungsten or ruthenium groups and tricobalt carbonyl clusters

The Pd(0)/Cu(I)-catalysed reactions between Co₃(μ₃-CBr) (CO)₉ and W(CCCCH)(CO)₃Cp gives the C₅ complex {Cp(OC)₃W}CCCCC{Co₃(CO)₉} (2). Similarly, Co₃(μ₃-CBr)(μ-dppm)(CO)₇ and W(CCCCH)(CO)₃Cp or Ru(CCCCH)(dppe)Cp* give {Cp(OC)₃W}CCCCC{Co₃(μ-dppm)(CO)₇} and {Cp*(dppe)Ru}CCCCC{Co₃(μ-dppmn)(CO)₇} (5). An attempt to prepare a C₃ analogue from Ru(CCH)(PPh₃)₂Cp and Co₃(μ₃-CBr)(CO)₉ gave instead the acyl derivative {Cp(Ph₃P)₂Ru}CCC(O)C{Co₃(CO)₈(PPh₃)} (7). The X-ray structures of 2, 5 and 7 are reported: the C₅ chains in 2 and 5 have an essentially unperturbed -CC-CC-C formulation.     

Investigation of noble metal nanoparticle ζ-potential effects on single-cell exocytosis function in vitro with carbon-fiber microelectrode amperometry

Since noble metal nanoparticles are increasingly found in consumer goods, there is a need for information about potential impacts of these nanoparticles on cellular function to avoid environmental and health risks associated with exposure. In this study, spherical Au and Ag nanoparticles of similar size were synthesized and modified to assess the effects of ζ-potential on immune cell function. Nanoparticle ζ-potential was controlled by employing surfactant exchange to generate nanoparticles with positive or negative surface charge. Mouse peritoneal mast cells (MPMCs) were then exposed to 5-15 μg ml(-1) of these nanomaterials, and uptake was assessed by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Uptake for positively charged nanoparticles was more efficient than for negatively charged nanomaterials, and all nanoparticles were taken up in a concentration-dependent manner. Following uptake, MPMC degranulation function was assessed using carbon-fiber microelectrode amperometry (CFMA), showing decreased quantal secretion of serotonin by MPMCs exposed to the positively charged Au nanoparticles and negatively charged Ag nanoparticles. The overall efficiency of the degranulation process (indicated by amperometric spike frequency) decreased for all Au-exposed MPMCs. However, only the negatively charged version of the Ag nanomaterial resulted in decreased MPMC degranulation efficiency. Further studies revealed that ionic Ag was partially responsible for the observed effects. Overall, these studies reveal the complex nature of interactions between noble metal nanomaterials and cells that result in perturbed cellular function and illustrate the necessity of thorough nanoparticle characterization for interpretation of cellular function assays.     

Location Matters: Site of Conjugation Modulates Stability and Pharmacokinetics of Antibody Drug Conjugates

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Highlights? Site-specific conjugation of diverse payloads can be achieved with transglutaminase ? Efficient conjugation was achieved at multiple positions throughout an antibody ? Site of conjugation has significant impact on ADC stability and pharmacokinetics ? Differences in ADC stability and pharmacokinetics are species dependent     

Essential Oil Compositions of Pinus Species (P. contorta Subsp. contorta,P. ponderosa var. ponderosa,and P. flexilis); Enantiomeric Distribution of Terpenoids in Pinus Species

Pinus species are important in traditional medicine throughout their ranges, and pine essential oils are of interest in aromatherapy and as topical treatments. In this work, the leaf (needle) essential oils of Pinus ponderosa var. ponderosa and Pinus contorta subsp. contorta from Oregon and Pinus flexilis growing in Idaho, have been obtained by hydrodistillation and analyzed by gas chromatographic techniques. The leaf essential oil of P. ponderosa was dominated by β-pinene (21.5–55.3%), methyl chavicol (8.5–41.5%), α-pinene (3.6–9.6%), δ-3-carene (3.6–6.2%), and α-terpineol (1.4–5.3%). The major components of P. contorta essential oil were β-phellandrene (23.8%), terpinen-4-ol (11.0%). The essential oil of P. flexilis was dominated by α-pinene (37.1%), β-pinene (21.9%), bornyl acetate (12.8%), and camphene (8.5%). Chiral gas chromatography revealed the enantiomeric ratios of α-pinene and limonene to be variable, but (−)-β-pinene predominated in Pinus essential oils.     

Mössbauer Studies of Stannous Fluoride Reactivity with Synthetic Tooth Enamel – A Model for the Tooth Cavity Protection Actions of Novel Dentifrices

Hyperfine Interactions - SnF2 is an important toothpaste ingredient, added for the provision of clinical efficacy for hard and soft tissue diseases and in breath protection. Synthetic calcium...     

Unprecedented Inversion of Selectivity and Extraordinary Difference in the Complexation of Trivalent f Elements by Diastereomers of a Methylated Diglycolamide

When considering f elements, solvent extraction is primarily used for the removal of lanthanides from ore and their recycling, as well as for the separation of actinides from used nuclear fuel. Understanding the complexation mechanism of metal ions with organic extractants, particularly the influence of their molecular structure on complex formation is of fundamental importance. Herein, we report an extraordinary (up to two orders of magnitude) change in the extraction efficiency of f elements with two diastereomers of dimethyl tetraoctyl diglycolamide (Me₂-TODGA), which only differ in the orientation of a single methyl group. Solvent extraction techniques, extended X-ray absorption fine structure (EXAFS) measurements, and density functional theory (DFT) based ab initio calculations were used to understand their complex structures and to explain their complexation mechanism. We show that the huge differences observed in extraction selectivity results from a small change in the complexation of nitrate counter-ions caused by the different orientation of one methyl group in the backbone of the extractant. The obtained results give a significant new insight into metal–ligand complexation mechanisms, which will promote the development of more efficient separation techniques.