Analytical Chemistry
DOI: 10.1021/acs.analchem.3c01011
[ASAP] Structural Evolution of Air-Exposed Layered Oxide Cathodes for Sodium-Ion Batteries: An Example of Ni-doped NaxMnO2
Chemistry of Materials
DOI: 10.1021/acs.chemmater.3c01196
Unraveling propylene oxide formation in alkali metal batteries
The increasing need for electrochemical energy storage drives the development of post-lithium battery systems. Among the most promising battery types are sodium-based battery systems. However, like its lithium predecessor, sodium batteries suffer from various issues like parasitic side reactions, which lead to a loss of active sodium inventory, thus reducing the capacity over time. Some problems in sodium batteries arise from an unstable solid electrolyte interphase (SEI) reducing its protective power. While it is known that the electrolyte affects the SEI structure, the exact formation mechanism of the SEI is not yet fully understood. Here we follow the initial SEI formation on sodium metal submerged in propylene carbonate with and without the electrolyte salt sodium perchlorate. We combine X-ray photoelectron spectroscopy, gas chromatography, and density functional theory to unravel the sudden emergence of propylene oxide after adding sodium perchlorate to the solvent. We identify the formation of a sodium chloride layer as a crucial step in forming propylene oxide by enabling precursors formed from propylene carbonate on the sodium metal surface to undergo a ring-closing reaction. We identify changes in the electrolyte decomposition process, propose a reaction mechanism to form propylene oxide and discuss alternatives based on known synthesis routes.
Mechanochemistry for healthcare: revealing the nitroso derivatives genesis in the solid state
Nitroso derivatives with unique characteristics have been extensively studied in various fields, including biology and clinical research. Even though it has been made an intense investigation of "nitrosable" components in many drugs and commonly consumed nutrients, there is still a need for a higher awareness about their formation and characterization. This study demonstrates how these derivatives can be produced through a mechanochemical procedure under solid-state conditions. The results include synthesizing previously unknown compounds with potential biological and pharmaceutical applications, such as a nitrosamine derived from a Diclofenac-like structure.
The Effect of Pulling and Twisting Forces on Chameleon Sequence Peptides
Chameleon sequences are amino acid sequences found in several distinct configurations in experiment. They challenge our understanding of the link between sequence and structure, and provide insight into structural competition in proteins. Here, we study the energy landscapes for three such sequences, and interrogate how pulling and twisting forces impact the available structural ensembles. Chameleon sequences do not necessarily exhibit multiple structural ensembles on a multifunnel energy landscape when we consider them in isolation. The application of even small forces leads to drastic changes in the energy landscapes. For pulling forces, we observe transitions from helical to extended structures in a very small span of forces. For twisting forces, the picture is much more complex, and highly dependent on the magnitude and handedness of the applied force as well as the reference angle for the twist. Depending on these parameters, more complex and more simplistic energy landscapes are observed alongside more and less diverse structural ensembles. The impact of even small forces is significant, confirming their likely role in folding events. In addition, small forces exerted by the remaining scaffold of a protein may be sufficient to lead to the adoption of a specific structural ensemble by a chameleon sequence.
Methodologies for Spontaneous Preparation of Chemosensors and Their Arrays Using Off‐the‐Shelf Reagents
Chemosensors are promising candidates to visualize molecular recognition information through colorimetric or fluorescence responses. In chemosensor designs, the following requirements should be considered; 1) molecular geometries with analytes, 2) mechanisms to cause optical changes upon analyte capture, and 3) solubility for sensing applications. On the other hand, the designs and realization of chemosensors covering the abovementioned requirements are still at the frontiers. In the conventional strategy, molecular geometries between receptors and analytes have been mainly considered. However, this approach confronts issues of synthetic efforts to obtain elaborate designs of chemosensors, which leads to a decrease in the water solubility of chemosensors derived from the complicated and aromatic molecular structures. Herein, this Review summarizes methodologies for self-assembled chemosensors only using off-the-shelf reagents to easily obtain various chemosensors without organic synthesis. The concept of self-assembled chemosensors comprising off-the-shelf reagents with water-solubility realizes not only the easy tuning of optical sensing properties but also chemical sensing in real samples. Through the comprehensive sensing applications using the facile self-assembled chemosensors and their arrays, the usability of off-the-shelf reagents in analytical chemistry will be clarified.
Review: Direct Lithium Extraction Using Intercalation Materials
Worldwide lithium (Li) demand has surged in recent years due to increased production of Li-ion batteries for electric vehicles and stationary storage. Li supply and production will need to increase such that the transition towards increased electrification in the energy sector does not become cost prohibitive. Many countries have taken policy steps such as listing Li as a critical mineral. Current commercial Li mining is mostly from dedicated mine sources, including ores, clays, and brines. The conventional ways to extract Li+ from those resources are through chemical processing. The environmental and economic sustainability of conventional Li processing has recently received increased scrutiny. Routes such as direct Li+ extraction may provide advantages relative to conventional Li+ extraction technologies, and one possible route to direct Li+ extraction includes leveraging of intercalation materials. Intercalation material processing has recently demonstrated high selectivity towards Li+ as opposed to other cations. Reviews and reports of direct Li+extraction with intercalation materials are limited, even as this technology has started to show promise in smaller scale demonstrations. This paper will review selective Li+ extraction via intercalation materials, including both electrochemical and chemical methods to drive Li+ in and out and efforts to characterize the Li+ insertion/deinsertion processes.
Benzylic C(sp3)‐H bond oxidation with ketone selectivity by a cobalt(IV)‐oxo embedded in a β‐barrel protein
Artificial metalloenzymes have emerged as biohybrid catalysts that allow to combine the reactivity of a metal catalyst with the flexibility of protein scaffolds. Here, we report the artificial metalloenzymes based on the β-barrel protein nitrobindin NB4, in which a cofactor [CoIIX(Me3TACD-Mal)]+X- (X = Cl, Br; Me3TACD = N,N´,N´´-trimethyl-1,4,7,10-tetraazacyclododecane, Mal = CH2CH2CH2NC4H2O2) was covalently anchored via a Michael addition reaction. These biohybrid catalysts showed higher efficiency than the free cobalt complexes for the oxidation of benzylic C(sp3)-H bonds in aqueous media. Using commercially available oxone (2KHSO5·KHSO4·K2SO4) as oxidant, a total turnover number of up to 220 and 97% ketone selectivity were achieved for tetralin. As catalytically active intermediate, a mononuclear terminal cobalt(IV)-oxo species [Co(IV)=O]2+ was generated by reacting the cobalt(II) cofactor with oxone in aqueous solution and characterized by ESI-TOF MS.
Acyclic Boryl Complexes of Copper(I)
Reaction of (6-Dipp)CuOtBu (6-Dipp = C{NDippCH2}2CH2, Dipp = 2,6-iPr2C6H3) with B2(OMe)4 provided access to (6-Dipp)CuB(OMe)2 via σ-bond metathesis. (6-Dipp)CuB(OMe)2 was characterised by NMR spectroscopy and X-ray crystallography and shown to be a monomeric acyclic boryl of copper. (6-Dipp)CuB(OMe)2 reacted with ethylene and diphenylacetylene to provide insertion compounds into the Cu-B bond which were characterised by NMR spectroscopy in both cases and X-ray crystallography in the latter. It was also competent in the rapid catalytic deoxygenation of CO2 in the presence of excess B2(OMe)4. Alongside π-insertion, (6-Dipp)CuB(OMe)2 reacted with LiNMe2 to provide a salt metathesis reaction at boron, giving (6-Dipp)CuB(OMe)NMe2, a second monomeric acyclic boryl, which also cuproborated diphenylacetylene. Computational interrogation validated these acyclic boryl species to be electronically similar to (6-Dipp)CuBpin.
Stereoselective Synthesis of Allylic Alcohols via Substrate Control on Asymmetric Lithiation
Allylic alcohols are a privileged motif in natural product synthesis and new methods that access them in a stereoselective fashion are highly sought after. Toward this goal, we found that chiral acetonide-protected polyketide fragments performing the Hoppe–Matteson–Aggarwal rearrangement in the absence of sparteine with high yields and diastereoselectivities rendering this protocol a highly valuable alternative to the Nozaki–Hiyama–Takai–Kishi reaction. Various stereodyads and -triads were investigated to determine their substrate induction. The mostly strong inherent stereoinduction was attributed to a combination of steric and electronic effects.