Ipso-Nitration of calix[6]azacryptands: intriguing effect of the small rim capping pattern on the large rim substitution selectivity

The ipso-nitration of calix[6]arene-based molecular receptors is a important synthetic pathway for the elaboration of more sophisticated systems. This reaction has been studied for a variety of capped calixarenes, and a general trend for the regioselective nitration of three aromatic units out of six in moderate to high yield has been observed. This selectivity is, in part, attributed to the electronic connection between the protonated cap at the small rim and the reactive sites at the large rim. In addition, this work highlights the fact that subtle conformational properties can drastically influence the outcome of this reaction.     

De Morgan classifying toposes

We present a general method for deciding whether a Grothendieck topos satisfies De Morgan's law (resp. the law of excluded middle) or not; applications to the theory of classifying toposes follow. Specifically, we obtain a syntactic characterization of the class of geometric theories whose classifying toposes satisfy De Morgan's law (resp. are Boolean), as well as model-theoretic criteria for theories whose classifying toposes arise as localizations of a given presheaf topos.     

Nickel containing diamond like carbon thin films

Diamond like carbon (DLC) coatings are well established for multiple applications. The electrical conductivity of DLC or amorphous carbon can be influenced by several orders of magnitude via doping with different metals. Depending on the deposition process hydrogen may be incorporated as well, thereby decreasing the conductivity. Recent investigations of DLC disclose nice piezoresistive properties.Our work was focused on Ni:a-C:H thin films on different substrates by reactive sputtering from a nickel target. Several carbon precursors were added to the sputtering gas to create an amorphous carbon hydrogen network with embedded crystal clusters. In order to optimize the piezoresistive properties we varied various process parameters. The piezoresistive response was monitored by measuring the resistance change during bending. Our Ni:a-C:H films develop gauge factors of approx. 12 in a wide range of process parameters.For sensor applications the temperature coefficient of resistance (TCR) is important as well. It depends on the metal concentration in the thin film and can be adjusted by the concentration of the incorporated nickel. It can be set to approximately zero in a wide temperature range of 80–400 K. The combination of a high gauge factor and a very small TCR is achieved and described in this paper.XRD measurements reveal nickel or nickel carbide clusters with diameters of approx. 8–30 nm depending on the metal concentration. The clusters crystallize in the hexagonal hcp structure which could be transformed into the cubic fcc structure of nickel by thermal annealing in a vacuum.     

Fe(II)LSCo(III)LS]2 ⇔ [Fe(III)LSCo(II)HS]2 photoinduced conversion in a cyanide-bridged heterobimetallic molecular square

The self-assembly of [Fe(III){B(pz)(4)}(CN)(3)](-) and [Co(II)(bik)(2)(S)(2)](2+) affords the diamagnetic cyanide-bridged [Fe(II)(LS)Co(III)(LS)](2) molecular square which is converted into the corresponding magnetic [Fe(III)(LS)Co(II)(HS)](2) species under light irradiation at relatively low temperatures.     

Formation of SnS nanoflowers for lithium ion batteries

SnS nanoflowers containing hierarchically organized nanosheet subunits were synthesized using a simple solution route, and they function as lithium ion battery anodes that maintain high capacities and coulombic efficiencies over 30 cycles.     

Indole- and Pyrazole-Glycyrrhetinic Acid Derivatives as PTP1B Inhibitors: Synthesis,In Vitro and In Silico Studies

Regulating insulin and leptin levels using a protein tyrosine phosphatase 1B (PTP1B) inhibitor is an attractive strategy to treat diabetes and obesity. Glycyrrhetinic acid (GA), a triterpenoid, may weakly inhibit this enzyme. Nonetheless, semisynthetic derivatives of GA have not been developed as PTP1B inhibitors to date. Herein we describe the synthesis and evaluation of two series of indole- and N-phenylpyrazole-GA derivatives (4a–f and 5a–f). We measured their inhibitory activity and enzyme kinetics against PTP1B using p-nitrophenylphosphate (pNPP) assay. GA derivatives bearing substituted indoles or N-phenylpyrazoles fused to their A-ring showed a 50% inhibitory concentration for PTP1B in a range from 2.5 to 10.1 µM. The trifluoromethyl derivative of indole-GA (4f) exhibited non-competitive inhibition of PTP1B as well as higher potency (IC₅₀ = 2.5 µM) than that of positive controls ursolic acid (IC₅₀ = 5.6 µM), claramine (IC₅₀ = 13.7 µM) and suramin (IC₅₀ = 4.1 µM). Finally, docking and molecular dynamics simulations provided the theoretical basis for the favorable activity of the designed compounds.     

Ground and Electronically Excited Singlet‐State Structures of 5‐Fluoroindole Deduced from Rotationally Resolved Electronic Spectroscopy and ab Initio Theory

The structure and electronic properties of the electronic ground state and the lowest excited singlet state (S₁) of 5‐fluoroindole (5FI) were determined by using rotationally resolved spectroscopy of the vibration‐less electronic origin of 5FI. From the parameters of the axis reorientation Hamiltonian, the absolute orientation of the transition dipole moment in the molecular frame was determined and the character of the excited state was identified as L_b.     

The Bergman projection on vector-valued L2-spaces with operator-valued weights

We characterize the boundedness of the Bergman projection on vector-valued $L^2$-spaces with operator-valued weights in terms of an appropriate condition of Muckenhoupt-type for the weight. This contrasts with the situation on Hardy spaces, where such characterizations are only possible in the finite-dimensional case.     

A Bayesian Whittaker–Henderson smoother for general‐purpose and sample‐based spectral baseline estimation and peak extraction

Raman spectroscopy is a well‐established technique that allows both chemical and structural analysis of materials. Raman spectra are often complex and extracting meaningful information is easily hindered by spectral interferences; one of the most significant sources being variations in background. Raman spectra have diverse sources of background making it hard to eliminate them or theoretically to predict the form of the baseline, which frequently varies between samples. Although many different methods for baseline removal have been proposed, most require some form of user input. User input is also subjective and consequently less reproducible than automated methods and variations in baseline subtraction can distort peak heights leading to erroneous results. We present a Bayesian Whittaker–Henderson smoother for spectral baseline estimation and peak extraction. It is a generalisation of the Whittaker–Henderson smoother, a regularised regression algorithm. We introduce hierarchical priors for model parameters of the smoother and propose a global aligner for consistent peak extraction across multiple spectra. We show that this novel smoother significantly outperforms several existing smoothers. Copyright © 2012 John Wiley & Sons, Ltd.