Chemistry methods : new approaches to solving problems in chemistry最新文献

Liquid Cell Transmission Electron Microscopy (LCTEM) is a great progression in nanostructure imaging, allowing the observation of chemical reactions in real time. It is widely reported, that this technique can be successfully used for analyzing nanoparticles synthesis, diffusion, aggregation and degradation. This gives a completely new insight into nanotechnological research. Normally, samples in TEM must be observed in vacuum, showing only the results of a performed experiment, whereas in situ observations in liquid environment provide information about the dynamics of the processes. LCTEM can show, how orientation of the particles/aggregates, surface roughness or solution flow rate influence the examined reaction. Those data are highly valuable for creating kinetic models of the reactions. There are however still some obstacles in LCTEM. Imaging of nanostructures in liquid environment is problematic since the electron beam reportedly may affect the observed sample. The beam modifies the temperature and pH of the liquid sample, changing the process dynamics. Therefore, its influence needs to be considered during in situ TEM observations. Nevertheless, LCTEM remains one of the highest achievements in the field of nanostructures imaging. In this review, recent achievements and developments of the LCTEM technique are presented.

Lithiated transition metal oxides are the most important cathode materials for lithium-ion batteries. Many efforts have been devoted in recent years to improving their energy density, stability, and safety, as demonstrated by thousands of publications. However, the commercialization of several promising materials is limited due to obstacles like stability limitations. To overcome the limitations of energetically high-voltage or high-capacity cathode materials, unconventional solutions for their surface engineering were suggested; among them, metal–organic frameworks (MOFs) and zeolites have been employed. MOFs possess favorable characteristics for stabilization goals, including manageable structures, topological control, high porosity, large surface area, and low density. This review article explores promising strategies for improving the electrochemical behavior of favorable cathode materials through surface modifications by using MOFs and zeolites. Investigating the potential of this frameworks-based surface engineering for high energy density batteries’ electrodes is essential for optimal control of their surface chemistry. It may be highly effective to upgrade the performance of high-energy cathode materials, thus extending the practical use of very high energy density rechargeable batteries.

Protein functionalisation for the development of imaging agents and antibody drug conjugates still often relies on statistical amidation of the protein through accessible lysine and cysteine residues, requiring protein to protein conjugation optimisation and can potentially impact the overall function. To combat this, focus has turned to developing proteins that have noncanonical amino acids incorporated into their structure, allowing for site-specific labelling and functionalisation. Herein we showcase the incorporation of non-canonical amino acids bearing a tetrazine or azide orthogonal coupling modality into biologics targeted to the prostate-specific membrane antigen and epidermal growth factor receptor respectively. The placement of these bioorthogonal residues into nanobody or single chain variable fragments (scFvs) is introduced by site-directed mutagenesis of the protein-coding DNA that allows for controlled insertion when these proteins are expressed. We show that bioorthogonal coupling of model compounds such as fluorophore or polymeric materials onto the protein does not significantly change the binding affinity, making these protein conjugation methods a powerful tool for development of simple customisable personalised targeted antibody-drug conjugates where affinity is retained.

Per- and polyfluoroalkyl substances (PFAS) are a class of hazardous pollutant that are ubiquitous in our modern world. Current research is driven by an increased awareness and concern regarding the safety of PFAS for the general population, while tightening regulations have prompted the need for detection and quantification techniques from a wide range of matrices. PFAS are a group of molecules offering unique behaviours, hazards, and complications that are not obvious or readily apparent from reading the literature. These peculiarities can impede or convolute analyses when not considered in experimental design. Drawing on the knowledge of a range of literature sources, this tutorial review looks to highlight and amalgamate the valuable suggestions and methodologies currently available to enable successful PFAS research in any laboratory.

Polymer electrolyte fuel cells (PEFCs) are regarded as a substitution for the combustion engine with high energy conversion efficiency and zero CO₂ emissions. Stable system operation requires control within a relatively narrow range of operating conditions to achieve the optimal output, leading to faults that can easily cause accelerated degradation when operating conditions deviate from the control targets. Performance recovery of the system can be realized through early fault diagnosis; therefore, accurate and effective diagnostic characterisation is vital for long-term serving. A review of off-line and on-line techniques applied to the fault diagnosis of fuel cells is presented in this work. Off-line approaches include electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), galvanostatic charge (GSC), visualisation-based and image-based techniques; the on-line methods can be divided into model-based, data-driven, signal-based and hybrid methods. Since each methodology has advantages and drawbacks, its effectiveness is analysed, and limitations are highlighted.

Modified silver nanoparticles with a self-assembled disulfide functionalized 2,2'-bipyridine (L1 and L2) monolayer, and the corresponding rhenium complex [Re(L2)(CO)₃Br] are shown to provide a method to position the nanoparticles at a water/dichloromethane interface forming a lustrous metal-like-liquid film (MeLLF) with a unique SERS response. The film formed using L2 showed divergent behaviour in the presence of a range of metal ions whilst bound to the surface. [Re(L)(CO)₃Br] (where L=2,2'-bipyridine, L1 and L2) in solution demonstrates a selective interaction with Hg²⁺, observed by UV-vis, emission and ¹H NMR spectroscopy, attributed to abstraction of the bromide. This interaction was demonstrated by subtle changes in the characteristic Raman Re-CO stretch at 510 cm⁻¹ both with the MeLLF, and when the film is immobilized in a PVA surface-exposed-nano-sheet (SENS). The work provides proof of concept that the organometallic complexes can be employed as “labels” to generate SERS-active nanoparticle films that possess detection capabilities.

The new possibility to perform operando X-ray absorption spectroscopy (XAS) in the laboratory expands the potential field of applications towards a broad research community. These applications are multidisciplinary at heart and benefit from joint expertise from different fields, most importantly chemistry, physics, geology, and instrumentation. Hence, a development of collaboration networks that combine skills and knowhow from different fields is highly beneficial in this endeavor. As operando laboratory-based XAS constitutes a highly interesting, advanced, and powerful characterization technique, we provide in this article practical guidelines for newcomers in the field, who would like to employ it. Here, we will describe ten important steps towards a successful operando laboratory-based XAS experiment, which are not only useful for the catalysis community, but for a much wider audience from other research fields, such as environmental chemistry as well as battery and fuel cell research.