Polymers Based on Stable Phenoxyl Radicals for the Use in Organic Radical Batteries

Polymers with pendant phenoxyl radicals are synthesized and the electrochemical properties are investigated in detail. The monomers are polymerized using ring‐opening metathesis polymerization (ROMP) or free‐radical polymerization methods. The monomers and polymers, respectively, are oxidized to the radical either before or after the polymerization. These phenoxyl radicals containing polymers reveal a reversible redox behavior at a potential of −0.6 V (vs Ag/AgCl). Such materials can be used as anode‐active material in organic radical batteries (ORBs).

     

An affine scaling method for optimization problems with polyhedral constraints

Recently an affine scaling, interior point algorithm ASL was developed for box constrained optimization problems with a single linear constraint (Gonzalez-Lima et al., SIAM J. Optim. 21:361–390, 2011). This note extends the algorithm to handle more general polyhedral constraints. With a line search, the resulting algorithm ASP maintains the global and R-linear convergence properties of ASL. In addition, it is shown that the unit step version of the algorithm (without line search) is locally R-linearly convergent at a nondegenerate local minimizer where the second-order sufficient optimality conditions hold. For a quadratic objective function, a sublinear convergence property is obtained without assuming either nondegeneracy or the second-order sufficient optimality conditions.     

Discovery of the Azaserine Biosynthetic Pathway Uncovers a Biological Route for α-Diazoester Production

Azaserine is a bacterial metabolite containing a biologically unusual and synthetically enabling α-diazoester functional group. Herein, we report the discovery of the azaserine (aza) biosynthetic gene cluster from Glycomyces harbinensis. Discovery of related gene clusters reveals previously unappreciated azaserine producers, and heterologous expression of the aza gene cluster confirms its role in azaserine assembly. Notably, this gene cluster encodes homologues of hydrazonoacetic acid (HYAA)-producing enzymes, implicating HYAA in α-diazoester biosynthesis. Isotope feeding and biochemical experiments support this hypothesis. These discoveries indicate that a 2-electron oxidation of a hydrazonoacetyl intermediate is required for α-diazoester formation, constituting a distinct logic for diazo biosynthesis. Uncovering this biological route for α-diazoester synthesis now enables the production of a highly versatile carbene precursor in cells, facilitating approaches for engineering complete carbene-mediated biosynthetic transformations in vivo.     

Highly enantioselective michael additions of indole to benzylidene malonate using simple bis(oxazoline) ligands: importance of metal/ligand ratio

[Structure: see text] Simple bis(oxazoline) ligands, especially azabis(oxazolines), can catalyze the copper-catalyzed addition of indoles to benzylidene malonates in up to >99% ee, provided that excess of chiral ligand is avoided. The paradigm followed in many asymmetric catalyses that an excess of chiral ligand with respect to the metal should improve enantioselectivity because a background reaction by free metal is suppressed, is not applicable here, which might call for revisiting some of the many copper(II)-bis(oxazoline)-catalyzed processes known.     

ℓ-group homomorphisms between reduced archimedean f-rings

Let A and B be reduced archimedean f-rings, A with identity e; let $A\,\mathop \to \limits^\gamma\,BLet A and B be reduced archimedean f-rings, A with identity e; let A \mathop ? ^g BA\,\mathop \to \limits^\gamma\,B be an ℓ-group homomorphism, and set w = γ (e). We show (with some vagaries of phrasing here) (1) γ = w·ρ for a canonical ℓ-ring homomorphism A \mathop ? ^r B (w)A\,\mathop \to \limits^\rho\,B (w), where B (w) is an extension of B in which w is a von Neumann regular element, and (2) for X _A ,X _B canonical representation spaces for A, B, γ is realized via composition with a unique partially defined continuous function from X _B to X _A .     

A General Synthetic Route to High-Quality Perovskite Oxide Nanoparticles and Their Enhanced Solar Photocatalytic Activity

The main limitations of current methods for synthesizing perovskite oxide (ABO₃) nanoparticles (NPs), e.g., the high reagent costs and sophisticated equipment, the long time and high-temperature processing, or multiple post-processing and thermal treatment steps, hamper their full study and potential application. Here, we use a facile low temperature (50 °C) chemical bath synthesis and only one annealing step to successfully produce high phase purity and crystalline quality nano-shaped rare-earth-based REMO₃ NPs (RE=La, Nd, Sm, Gd; M=Fe, Mn, Al). We also show the versatility of this approach by fabricating La_0.7Sr_0.3MnO₃ solid solution and non-RE-based BiFeO₃ perovskite. To assess the potential of the as-prepared REFeO₃ and REMnO₃ NPs, they are used for photocatalytic degradation of the norfloxacin antibiotic and show high efficiency. We believe this easy, robust, versatile, and general route for synthesizing ABO₃-based NPs can be further explored in the vast perovskite family and beyond.