Synthesis, structure, and metal complexation behavior of a new type of functionalized chiral phenanthroline derivative

SmI(2) serves as an effective promoter for the coupling of 1,10-phenanthroline with an epoxide to generate a new class of chiral, functionalized ligands that readily form complexes with metals. Structural studies of the resulting phenanthroline derivative and two of its metal complexes are reported.     

Facile preparation of a highly functionalized tetrahydropyran by catalytic hydrogenation of an oxazoline

2-Amino-1,5-anhydro-2-deoxy-D-glucitol, a highly functionalized tetrahydropyran, is a versatile building unit in many natural products. A facile route to this type of synthetic building unit from the corresponding 2-aminopyranoses, as exemplified by an application to D-glucosamine, is outlined. A simple catalytic hydrogenation at C-1 of an oxazoline constructed from the corresponding 2-aminopyranose results in the desired product.     

Analysis of size-classified fine and ultrafine particulate matter on substrates with laser-induced breakdown spectroscopy

Airborne particulate matter in the fine (0.1 µm–2.5 µm) and ultrafine (≤ 0.1 µm) size range is supposed to affect human health significantly. Smaller particles intrude more deeply into the lungs, so that an organism directly absorbs toxic compounds. Therefore, knowledge of the size-dependent composition of airborne particles is required to determine their health hazard. In this paper, we demonstrate the application of laser-induced breakdown spectroscopy to directly analyze size-classified particulate matter samples without any sample preparation. Samples analyzed are collected on filter substrates using a cascade impactor. Greased aluminum foils are used as filter substrate. To reduce ablation of the substrate material, low pulse energies of 0.6 mJ are used for plasma excitation. The plasma light is observed using an Echelle spectrometer. The effect of ambient gas and pressure on the line intensities is studied. Calibration samples for 14 elements relevant for human health were produced, and the system was calibrated for concentration ranges up to four orders of magnitude. Finally, the collected samples of particulate originating from steel-making processes were analyzed. The measurements show that the composition of these particles depends strongly on their size. For example, the elements lead, cadmium and copper are enriched within particles of about 200 nm diameter.     

Nonsmooth Bundle Trust-region Algorithm with Applications to Robust Stability

We propose a bundle trust-region algorithm to minimize locally Lipschitz functions which are potentially nonsmooth and nonconvex. We prove global convergence of our method and show by way of an example that the classical convergence argument in trust-region methods based on the Cauchy point fails in the nonsmooth setting. Our method is tested experimentally on three problems in automatic control.     

A mathematical model for continuous crystallization

J. Banasiak We discuss a mixed‐suspension, mixed‐product removal crystallizer operated at thermodynamic equilibrium. We derive and discuss the mathematical model based on population and mass balance equations and prove local existence and uniqueness of solutions using the method of characteristics. We also discuss the global existence of solutions for continuous and batch mode. Finally, a numerical simulation of a continuous crystallizer in steady state is presented. Copyright © 2015 John Wiley & Sons, Ltd.     

High-connectivity networks: characterization of the first uninodal 9-connected net and two topologically novel 7-connected nets

Ring and cage aggregates containing the large alkali metals potassium or rubidium have proven to be excellent building blocks for the creation of high-connectivity nets, as demonstrated by their use as septahedral and nonahedral nodes in synthesis of two new types of 7-connected nets and the first ever example of a 9-connected net.     

New side-chain poly(methacryl-rotaxanes) bearing cyclodextrins as non-covalently anchored ring components. Chemoenzymatic synthesis and degradation

The chemoenzymatic synthesis of new side-chain polyrotaxanes ( 6 ) bearing non-covalently attached cyclodextrins is described. Starting from 11-methacryloylaminoundecanoic acid, up to 8 units of 12-hydroxylauric acid were condensed in the presence of a lipase from Candida antarctica. They were copolymerized with methyl methacrylate to comb-like polymers ( 4 ) bearing free carboxylic groups at the end of the oligoester side chains. These free carboxylic groups were then condensed chemically with a nucleophilic barrier group, N-(4-aminobutanoyl)-4-triphenylmethylaniline ( 5 ), in the presence of dimethylated β-cyclodextrin, yielding new polyrotaxanes that contain statistically more than 1 ring component per side chain.     

Metal—-Metal “Communication” of Rh or Pd with Nd in Novel Heterobinuclear Complexes

The reaction of a neodymium “ate” complex and an electron-rich transition metal chloride by salt elimination is an efficient method for synthesizing heterobinuclear compounds which contain a lanthanide and a Group 9 or 10 metal [Eq. (1), H₂Ap=2-amino-4-methylpyridine]. The use of bisaminopyridinato ligands allows extremely short distances between Rh or Pd and Nd.     

Desorption electrospray ionization using an Orbitrap mass spectrometer: Exact mass measurements on drugs and peptides

Desorption electrospray ionization (DESI) is implemented on an Orbitrap mass spectrometer. The ion source is described and applications which utilize the high-resolution capabilities of the Orbitrap are emphasized, including the characterization of peptides and active ingredients in pharmaceutical tablets. Measurements are made in less than 1 s at a resolution of 60,000. The implications of the data for the mechanisms of DESI are discussed.     

Electronic configuration of high-spin imidazole-ligated iron(II) octaethylporphyrinates

The preparation and characterization of two new five-coordinate, imidazole-ligated, high-spin iron(II) octaethylporphyrinates is described. [Fe(OEP)(1,2-Me2Im)] and [Fe(OEP)(2-MeHIm)] have been characterized by X-ray structure determinations and temperature-dependent M?ssbauer spectroscopy in zero and applied magnetic fields. The distinction between imidazole-ligated and other ligands in high-spin iron(II) porphyrinates, noted for a series of tetraarylporphyrinate derivatives (Hu, C.; Roth, A.; Ellison, M. K.; An, J.; Ellis, C. M.; Schiltz, C. E.; Scheidt, W. R. J. Am. Chem. Soc. 2005, 127, 5675), is seen here as well. The sign of the quadrupole-splitting constant is again negative, which is unique to the imidazole-ligated derivatives and suggests a distinct electronic structure. The derivatives again display a remarkable temperature dependence in the quadrupole splitting, which is also seen for deoxymyoglobin and -hemoglobin. Structural features for the two new derivatives are similar to those seen earlier, although the core conformations show somewhat more doming character.