Low‐Background,Highly Sensitive DNA Biosensor by Using an Electrically Neutral Cobalt(II) Complex as the Redox Hybridization Indicator

An electrically neutral cobalt complex, [Co(GA)₂(phen)] (GA=glycollic acid, phen=1,10‐phenathroline), was synthesized and its interactions with double‐stranded DNA (dsDNA) were studied by using electrochemical methods on a glassy carbon electrode (GCE). We found that [Co(GA)₂(phen)] could intercalate into the DNA duplex through the planar phen ligand with a high binding constant of 6.2(±0.2)×10⁵ M ^?1. Surface studies showed that the cobalt complex could electrochemically accumulate within the modified dsDNA layer, rather than within the single‐stranded DNA (ssDNA) layer. Based on this feature, the complex was applied as a redox‐active hybridization indicator to detect 18‐base oligonucleotides from the CaMV35S promoter gene. This biosensor presented a very low background signal during hybridization detection and could realize the detection over a wide kinetic range from 1.0×10^?14 M to 1.0×10^?8 M , with a low detection limit of 2.0 fM towards the target sequences. The hybridization selectivity experiments further revealed that the complementary sequence, the one‐base‐mismatched sequence, and the non‐complementary sequence could be well‐distinguished by the cobalt‐complex‐based biosensor.     

Template‐Free Hydrothermal Synthesis of Mesoporous MgO Nanostructures and Their Applications in Water Treatment

The controlled synthesis of Mg(OH)₂ nanowires and microflowers composed of nanoplates was successfully achieved by a template‐free hydrothermal synthetic method. It was found that the reaction medium played a crucial role in the morphological control of the precursor nanostructures. The high polarity of water molecules favored the polar growth of the precursor, resulting in the formation of nanowires with a diameter of 80 nm, whereas a mixed water/ethanol medium with a lower degree of polarity led to the formation of microflowers. Moreover, mesoporous MgO nanostructures could be obtained by further annealing these as‐prepared precursors in air at 500 °C for 2 h. During thermal treatment, the wire‐ and flower‐like morphologies were retained. Porosity formation was due to thermal decomposition of Mg(OH)₂ and release of H₂O. Both the mesoporous MgO nanowires and microflowers showed superior ability of adsorbing the organic dye methyl orange, and thus they are promising candidates for polluted water treatment.     

Recycling of Primary Lithium Batteries Production Residues

Production waste of primary lithium batteries constitutes a considerable secondary lithium feedstock. Although the recycling of lithium batteries is a widely studied field of research, the metallic residues of non-rechargeable lithium battery production are disposed of as waste without further recycling. The risks of handling metallic Li on a large scale typically prevent the metal from being recycled. A way out of this situation is to handle Li in an aqueous solution, from where it can be isolated as Li₂CO₃. However, the challenge in hydrometallurgical treatment lies in the high energy release during dissolution and generation of H₂. To reduce these process-related risks, the Li sheet metal punching residues underwent oxidative thermal treatment from 300 to 400 °C prior to dissolution in water. Converting Li metal to Li₂O in this initial process step results in an energy release reduction of ∼70 %. The optimal oxidation conditions have been determined by experimental design varying three factors: temperature, Li metal sheet thickness, and residence time. With 96.9±2.6 % almost the entire Li amount is converted to Li₂O, after 2.5 h treatment at 400 °C for a Li sheet thickness of 1.99 mm. Final precipitation with CO₂ yields 85.5±3.0 % Li₂CO₃. Using pure Li sheets, the product Li₂CO₃ is obtained in battery-grade quality (>99.5 %). Non-precipitated Li is recirculated into the process on the stage of dissolving Li₂O, thus avoiding loss of material.     

Variability in the Formation and Framework Polymorphism of Metal-organic Frameworks based on Yttrium(III) and the Bifunctional Organic Linker 2,5-Dihydroxyterephthalic Acid

Depending on the solvothermal reaction conditions, we obtained three different metal-organic frameworks with yttrium(III) as metal component and 2,5-dihdyroxyterepthalic acid (H₄dhtp) as bifunctional organic linker: Y₂(H₂dhtp)₃(dmf)₄ · (dmf)₂ (CPO-29) contains dinuclear, paddle-wheel like inorganic secondary building units (SBUs) connected by the organic linker to a network with α-Po topology, while Y₂(H₂dhtp)(dhtp)(dmf)₂ (CPO-30) and Y₂(H₂dhtp)(dhtp)(dmf)₂(H₂O)₂ · (H₂O)₄ (CPO-31) contain one-dimensional inorganic SBUs that differ in how the half- and fully deprotonated ligands are connected to and arranged around them. Only the carboxylic acid groups of the organic linker are deprotonated in CPO-29, while CPO-30 and CPO-31 contain both 2,5-dihydroxyterephthalate (H₂dhtp^2–) linkers and fully deprotonated 2,5-dioxidoterephthalate (dhtp^4–) linkers. All three compounds contain large volumes filled with solvent, but we were able to demonstrate permanence of porosity only for CPO-30. Variable temperature powder X-ray diffraction reveals that CPO-29 and CPO-31 undergo discontinuous phase transitions upon heating, and the flexibility of the framework structure indicated by these might be the reason for the inability to access the pore volume. Desolvated CPO-30 and CPO-31 are polymorphs, whose network structures differ in whether the H₂dhtp^2– and dhtp^4– linkers are located in cis or trans arrangement around the inorganic SBU.     

Charge‐Induced Unzipping of Isolated Proteins to a Defined Secondary Structure

Here we present a combined experimental and theoretical study on the secondary structure of isolated proteins as a function of charge state. In infrared spectra of the proteins ubiquitin and cytochrome c, amide I (C=O stretch) and amide II (N–H bend) bands can be found at positions that are typical for condensed‐phase proteins. For high charge states a new band appears, substantially red‐shifted from the amide II band observed at lower charge states. The observations are interpreted in terms of Coulomb‐driven transitions in secondary structures from mostly helical to extended C₅‐type hydrogen‐bonded structures. Support for this interpretation comes from simple energy considerations as well as from quantum chemical calculations on model peptides. This transition in secondary structure is most likely universal for isolated proteins that occur in mass spectrometric experiments.     

A Fluorescent Sensor for Dual‐Channel Discrimination between Phosgene and a Nerve‐Gas Mimic

The ability to analyze highly toxic chemical warfare agents (CWAs) and related chemicals in a rapid and precise manner is essential in order to alleviate serious threats to humankind and public security caused by unexpected terrorist attacks and industrial accidents. In this investigation, we designed a o‐phenylenediamine‐pyronin linked dye that is capable of both fluorogenic and colorimetric discrimination between phosgene and the prototypical nerve‐agent mimic, diethyl chlorophosphate (DCP) in the solution or gas phase. Moreover, this dye has been used to construct a portable kit that can be employed for real‐time monitoring of DCP and phosgene in the field, both in a discriminatory manner, and in a simple and safe way.     

Thermally Induced Carbohydroxylation of Styrenes with Aryldiazonium Salts

The radical carbohydroxylation of styrenes with aryldiazonium salts has been achieved under mild thermal conditions. A broad range of aryldiazonium salts was tolerated, and the reaction principle based on a radical–polar crossover mechanism could be extended to carboetherification as well as to a two‐step, metal‐free variant of the Meerwein arylation leading to stilbenes.     

Electrolytic Formation of Crystalline Silicon/Germanium Alloy Nanotubes and Hollow Particles with Enhanced Lithium‐Storage Properties

Crystalline silicon(Si)/germanium(Ge) alloy nanotubes and hollow particles are synthesized for the first time through a one‐pot electrolytic process. The morphology of these alloy structures can be easily tailored from nanotubes to hollow particles by varying the overpotential during the electro‐reduction reaction. The continuous solid diffusion governed by the nanoscale Kirkendall effect results in the formation of inner void in the alloy particles. Benefitting from the compositional and structural advantages, these SiGe alloy nanotubes exhibit much enhanced lithium‐storage performance compared with the individual solid Si and Ge nanowires as the anode material for lithium‐ion batteries.     

Copper‐Catalyzed Aerobic Oxidative Reaction of Sulfonyl Hydrazides with Alcohols: An Easy Access to Sulfinates

A Cu‐catalyzed aerobic oxidative reaction between sulfonyl hydrazides and alcohols has been developed. In this reaction, sulfonyl hydrazides act as the sulfinic acid precursors to react with alcohols, resulting in sulfinic esters with up to 72 % yield. This catalytic system tolerates a wide range of sulfonyl hydrazide substrates, and represents a new strategy for the transformation of readily available sulfonyl hydrazides.