All‐Optical Integrated Logic Operations Based on Chemical Communication between Molecular Switches

Molecular logic gates process physical or chemical “inputs” to generate “outputs” based on a set of logical operators. We report the design and operation of a chemical ensemble in solution that behaves as integrated AND, OR, and XNOR gates with optical input and output signals. The ensemble is composed of a reversible merocyanine‐type photoacid and a ruthenium polypyridine complex that functions as a pH‐controlled three‐state luminescent switch. The light‐triggered release of protons from the photoacid is used to control the state of the transition‐metal complex. Therefore, the two molecular switching devices communicate with one another through the exchange of ionic signals. By means of such a double (optical–chemical–optical) signal‐transduction mechanism, inputs of violet light modulate a luminescence output in the red/far‐red region of the visible spectrum. Nondestructive reading is guaranteed because the green light used for excitation in the photoluminescence experiments does not affect the state of the gate. The reset is thermally driven and, thus, does not involve the addition of chemicals and accumulation of byproducts. Owing to its reversibility and stability, this molecular device can afford many cycles of digital operation.     

Isolation and Hydrogenation of a Complex with a Terminal Iridium–Nitrido Bond

An N for Ir : The synthesis and X‐ray crystal structure of a late‐transition‐metal complex with a terminal nitrido ligand and its hydrogenation to the related amido complex are reported (see scheme).

     

Application of ultrasound‐assisted liquid–liquid microextraction coupled with gas chromatography and mass spectrometry for the rapid determination of synthetic cannabinoids and metabolites in biological samples

The constant emergence of new psychoactive substances is a challenge to clinical and forensic toxicologists who need to constantly update analytical techniques to detect them. A large portion of these substances are synthetic cannabinoids. The aim of this study was to develop a rapid and simple method for the determination of synthetic cannabinoids and their metabolites in urine and blood using gas chromatography–mass spectrometry. The method involves an ultrasound‐assisted dispersive liquid–liquid microextraction that implies a rapid procedure, giving excellent extraction efficiencies with minimal use of toxic solvents. This is followed by silylation and analysis with gas chromatography–mass spectrometry. The chromatographic method allows for the separation and identification of 29 selected synthetic cannabinoids and some metabolites. The method was validated on urine and blood samples with the ability to detect and quantify all analytes with satisfactory limits of detection (from 1 to 5 ng/mL), limits of quantification (5 ng/mL), and selectivity and linearity (in the range of 5–200 ng/mL). The developed assay is highly applicable to laboratories with limited instrumental availability, due to the use of efficient and low‐cost sample preparation and instrumental equipment. The latter may contribute to enhance the detection of new psychoactive substances in clinical and forensic toxicology laboratories.     

Doping dependence of the pressure response of Tc in the SmO(1-x)F(x)FeAs superconductors

The superconducting transition temperature of the high-Tc SmO1-xFxFeAs superconductors increases monotonically as the F-doping level x increases to 0.20. High-pressure magnetization experiments reveal a strong sensitivity of Tc to interatomic distances in the underdoped regime (x 相似文献   

Crystal structure of the new FeSe(1-x) superconductor

The newly discovered superconductor FeSe(1-x) (x approximately 0.08, T(c)(onset) approximately 13.5 K at ambient pressure rising to 27 K at 1.48 GPa) exhibits a structural phase transition from tetragonal to orthorhombic below 70 K at ambient pressure-the crystal structure in the superconducting state shows remarkable similarities to that of the REFeAsO(1-x)F(x) (RE = rare earth) superconductors.     

Gilch Synthesis of Poly(ortho‐Phenylene Vinylenes): A Powerful Access to High‐Molecular‐Weight Blue‐Emitting Polymers

For the first time, the successful Gilch synthesis of poly(ortho‐phenylene vinylenes) (ortho‐PPVs) is reported. The molar mass of the constitutionally homogeneous ortho‐PPVs reaches values as high as M_w ≈ 300 000 Da. The ortho‐connectivity of the repeating units forces the chains to assume closely packed conformations even in good solvents. Significant perturbation of the π–electron systems and considerable shortening of the conjugation lengths are the consequences. UV–vis absorption and photoluminescence maxima consequently are shifted clearly toward shorter wavelengths compared to, e.g., classic para‐PPVs.

     

From favorable atomic configurations to supershell structures: a new interpretation of conductance histograms.

Simulated minimum cross-section histograms of breaking Al nanocontacts are produced using molecular dynamics. The results allow a new interpretation of the controverted conductance histogram peaks based on preferential geometrical arrangements of nanocontact necks. As temperature increases, lower conductance peaks decrease in favor of broader and higher conductance structures. This reveals the existence of shell and supershell structures favored by the increased mobility of Al atoms.     

Redetermination of the X-ray structure of nitroxylcobalamin: base-on nitroxylcobalamin exhibits a remarkably long Co-N(dimethylbenzimidazole) bond distance

The X-ray structures of three new crystals of nitroxylcobalamin (NOCbl) have been determined. Unlike our earlier reported structure in which NOCbl was partially oxidized (L. Hannibal, C. A. Smith, D. W. Jacobsen and N. E. Brasch, Angew. Chem., Int. Ed. 2007, 46, 5140), the O atom of the nitroxyl ligand is located in a single position with a N=O bond distance of 1.12-1.14 ?, consistent with a double bond. The Co-N-O angle is in the 118.9-120.3 ? range. The α-axial Co-N(dimethylbenzimidazole) (Co-NB3) bond distance is a remarkable 2.32-2.35 ? in length, ~0.1 ? longer than that reported for all other cobalamin structures. The change in the Gibbs free energy for the base-on/base-off equilibrium now correlates extremely well with the Co-NB3 bond distance, as observed for other cobalamins.     

A Streamlined,Safe and Sustainable Process for Gemlapodect

The research efforts to attain a suitable process for the timely delivery of Gemlapodect for initial toxicological and phase 1/2 clinical studies are described. The original discovery chemistry route was hampered by considerable safety issues and low overall yield. The safety issues were solved by the introduction of a copper-catalyzed oxidative cyclization while a novel process for the synthesis of the pyrazole building block as well as the implementation of a palladium-catalyzed coupling between the pyrazole amide and the bromo-triazolopyridine scaffolds contributed to improve the route efficiency. Overall, a safe and sustainable process was attained that allowed the production of up to 19.2 kg of drug substance with a reduced number of steps and an increased overall yield.