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

The Front Cover illustrates a novel approach to use printed electrochemical strips for triggering the controlled release of copper ions onto skin for wound healing application. Using the same portable device, copper ions are delivered and subsequently the amount is monitored, in order to personalize the treatment and evaluate its efficacy. The all-in-one system is easily generalizable towards the delivery of other species of interest depending on the therapeutic need. For more details, see the Research Article by Sima Singh, Stefano Cinti, and co-workers (DOI: 10.1002/cmtd.202400079.

Herein we introduce a novel concept: a sustainable, integrated approach to digital healthcare, utilizing a portable electrochemical strip to trigger therapeutic species release and assess their occurrence. For the first time, a nanomodified, screen-printed strip electrochemically triggers the release of metal ions, delivers them to the target site in combination with hydrogel and monitors them using the same device. To demonstrate the novel concept, copper ions have been considered a model species to be delivered and monitored on the skin. The integration of electroanalysis, drug delivery, miniaturization, and material science underscores the potential for a cost-effective breakthrough in personalized therapies, paving the way for numerous applications and addressing the current limitations of conventional technologies, such as time, complexity, and equipment.

The Front Cover illustrates the investigation of a supported metal catalyst containing both single atoms and nanoparticles using X-ray absorption spectroscopy (XAS). The MS-QuantEXAFS method, integrating density functional theory with XAS analysis, enables quantification of the two species. For more details, see the Research Article by Rachita Rana, Simon R. Bare, Ambarish R. Kulkarni, and co-workers (DOI: 10.1002/cmtd.202400020).

The increased demand for the synthesis of Csp³ enriched motifs and the urgency of discovering new drugs requires the development of more efficient technologies and synthetic tools to accelerate drug discovery processes. Herein, we report a fully automated strategy for the addition of Csp³ enriched building blocks onto olefins via Giese addition to forge Csp³−Csp³ bonds. The developed fully automated protocol allowed the in-situ conversion of aldehydes (non-redox-active species) to electroactive imidazolidines and their use as precursors of C-centered radicals under photoredox catalyzed conditions for the synthesis of building blocks and bioactive compound libraries by synthesizing sp³-enriched compounds.

A ¹⁷O solid-state NMR method for salt/co-crystal discrimination in binary compounds of carboxylic acids is presented. The method incorporates a quick and relatively inexpensive labelling protocol for mechanochemical ¹⁷O enrichment of the carboxyl oxygen positions, as previously described by Metro et al. Angew. Chem. 2017, 56, 6803, followed by a visual interpretation of the recorded ¹⁷O solid-state magic-angle spinning (MAS) NMR spectra in terms of the nature of the enriched oxygen sites in the prepared binary compound. Care must be taken where variable-temperature changes in the ¹⁷O MAS spectra are observed. Nevertheless, we observe that, at low temperatures, the averaging effect of chemical exchange of the carboxyl/carboxylate moieties can be avoided and two well separated ¹⁷O lines are obtained for a carboxylic acid, whereas the almost equivalent carboxylate oxygen sites give rise to a single NMR signal. The method is illustrated in two cases, one in which salts can be identified also from their ¹H solid-state NMR spectra by the absence of high ppm resonances due to hydrogen bonding, and another one, the more general case of organic crystals with multiple hydrogen bonding, where only ¹⁷O solid-state NMR spectra can be employed for salt/co-crystal discrimination. A quantitative analysis of ¹⁷O solid-state NMR spectral parameters can provide useful information in structural studies by NMR crystallography approaches.

We present the Multi-site (MS) QuantEXAFS approach, designed to model the EXAFS data from samples containing an element in different local bonding geometries. Building upon our QuantEXAFS method, which maps experimental extended X-ray absorption fine structures (EXAFS) data to DFT-optimized structures, MS-QuantEXAFS introduces the key capability to probe fractional contributions of multiple sites that may be present in an experimental sample. Specifically, we demonstrate effectiveness of this technique by investigating mixed samples containing known fractions of site-isolated subsurface Pt/MgO with Pt nanoparticles uniformly supported on MgO. The ‘site-fractions’ obtained through MS-QuantEXAFS closely match (i. e., ±6%) the known fractions of the physically mixed samples. This approach has been generalized to other oxides, and thus represents an important advance in quantifying the speciation of non-uniform catalyst samples.

A time resolved in situ X-ray powder diffraction study using synchrotron radiation allowed for describing the evolution of the zeolite FAU structure during the development of a zeolite-templated carbon (ZTC) in its porous voids. During the ZTC formation the intensity decrease of most zeolite reflections and the simultaneous rise in intensity of the 222 reflection (of null intensity in the pristine zeolite) was observed. Full pattern profile fitting by Rietveld refinement allowed for achieving a detailed description of the underlying chemistry, with coincident pore filling with carbon atoms in specific positions and framework distortion. Monitoring the intensity profiles of the 222 reflection allowed assessment of the energetics of the ZTC formation. Our results contribute to a better understanding of the phenomena involved on the atomic scale in ZTC synthesis.

Reactor automation is a transformative force for chemical processes, but the potential of reaction monitoring for machine-assisted autonomous biocatalytic reaction optimization is still largely unexplored. To address this gap, we report on automated reactor optimization for biocatalytic flow-through microreactors. For this purpose, the inline NMR analysis of an enzymatically catalyzed stereoselective reduction of a prochiral diketone was combined with a self-developed open-source analysis and control software. The algorithm is continuously fed with spectra from a benchtop NMR instrument acquired from a reaction solution from a microreactor filled with biocatalytically active materials and adjusts the flow rate of the pumps to achieve predetermined target concentrations of the product. We show that through this automated coupling of data analysis and process parameterization, for example, maximum conversion efficiency can be achieved for a given bioreactor. This work illustrates the potential of inline NMR reaction monitoring for biocatalytic processes and provides a starting point for innovation to develop automated processes for precision biocatalysis through integrated data analysis.

The incorporation of a labeled ¹³C atom provides a plethora of opportunities in organic synthesis and catalysis. Structure of complicated compounds can be successfully confirmed using the precise location of a labeled carbon atom; a reaction mechanism can be supported by the presence or absence of a label in reaction products; metabolic pathways of biological compounds can be found out depending on labeled products; the concentration of analyzed labeled compounds can be significantly lower for recording and successful interpretation of NMR spectra, etc. This review aims to provide a researcher with common and promising strategies for the synthesis of labeled compounds so that a researcher can select an appropriate route to save valuable labeled material. All the labeling approaches were considered based on starting labeling source. Ideological aim of the review is to demonstrate the opportunities for label incorporation so that a researcher can find the improvements in his own topic using labeled compounds. Utilization of labeled compounds in catalysis and studying reaction mechanisms were also considered to demonstrate the capabilities of labeled compounds, which may be useful in specific tasks and applications. The potential of labeled compounds in bioactive compound metabolite analysis was demonstrated on selected examples.

Mononuclear inorganic diradical species are scarce. Here, we confirm, via X-ray absorption spectroscopy in the gas phase combined with computational studies, the oxygen-centered diradical character of the tetraoxidorhenium(VII) cation. A dioxido-superoxido isomer, close in energy to the diradical, is also found, where rhenium appears in its rare oxidation state of +6. Addition of one or two hydrogen atoms to [Re,O₄]⁺ forms hydroxido ligands, and strongly disfavors isomers with any oxygen-oxygen bond. This adds spectroscopic characterization of the rhenium oxidation state and the nature of ligands to the known ability of [Re,O₄]⁺ to perform two consecutive hydrogen-atom abstraction reactions from methane, and demonstrates that pentaatomic [Re,O₄]⁺ combines a metal center in its highest oxidation state with two oxygen-centered radical ligands in a highly reactive species.