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

Structural colors have been regarded as an ideal alternative to pigments because of the advantages of environmental friendliness, resistance to fading, especially in the fields of textile dyeing and printing, which is highly polluted in traditional ways and needs to be upgraded. They are generated by the interaction between the micro/nano structure of the material surface and the incident light, which is closely related to the sizes and periods of the structures. Based on different nano arrangements, the structures can be roughly divided into photonic crystals and non-photonic crystals. In this review, we summarized recent research progress in structural coloration of fibers and textiles. Learning from nature, researchers proposed various methods to fabricate biomimetic structural colors, and the applications of structural colored fibers and textiles were extended. The challenges and perspectives were also presented. Hopefully, reference for the design and preparation of structural color-based textiles can be inspired.

A major challenge in the development of molecular photoswitches capable of storing and releasing solar energy is to simultaneously realize many of the performance criteria required of the switches for such applications. Here, we take on this challenge by introducing an all-around performance descriptor that combines three key criteria (related to energy density, storage time and light-absorption characteristics), and by using density functional theory methods to calculate its values for 52 newly designed dihydroazulene/vinylheptafulvene (DHA/VHF) switches. Thereby, we are able to identify several switches with excellent overall properties that contain a structural motif absent in all DHA/VHF compounds previously considered for solar-energy storage. For some of these switches, we also provide retrosynthetic analyses and demonstrate that they form the energy-storing VHF isomer through a facile DHA→VHF photoisomerization reaction. All in all, we conclude that these switches show great promise for further development towards applications in solar-energy storage.

The identification of biotransformation products of drug compounds is a crucial step in drug development. Over the last decades, liquid chromatography-mass spectrometry (LC-MS) has become the method of choice for metabolite profiling because of its high sensitivity and selectivity. However, determining the full molecular structure of the detected metabolites, including the exact biotransformation site, remains challenging on the basis of MS alone. Here we explore infrared ion spectroscopy (IRIS) as a novel MS-based method for the elucidation of metabolic pathways in drug metabolism research. Using the drug midazolam as an example, we identify several biotransformation products directly from an in vitro drug incubation sample. We show that IR spectra of the aglycone MS/MS fragment ions of glucuronide metabolites establish a direct link between detected phase I and phase II metabolites. Moreover, using quantum-chemically computed IR spectra of candidate structures, we are able to assign the exact sites of biotransformation in absence of reference standards. Additionally, we demonstrate the utility of IRIS for structural elucidation by identifying several ring-opened midazolam derivatives formed in an acidic environment.

For years now, High-Throughput Experimentation (HTE) have been applied to organic chemistry for reaction optimization and reaction discovery as a powerful tool for time and cost reduction. If this technology has been first developed by and for industry, and used as a routine method today, some academic researchers, including in Europe, are still challenging the accessibility of HTE as a general and daily used technology. One of the reasons is probably the expensive cost of such facilities development, which generally involves automation with robots, dedicated research teams, and expensive analytical instrumentation. This paper aims at bringing to light the accessibility of batch HTE with a minimum of instrumentation and cost, in order to help organic chemists to accelerate the discovery and optimization of new synthetic methodology, leading them to reduce their costs and empower their innovative research.

With this work, we wish to facilitate further developments in photocatalysis by proposing reliable methods for the computational pre-screening of potential photocatalysts. To this end, we have developed a new benchmark strategy, and we have applied it to evaluate the predictions given by two wavefunction and several density functional theory (DFT) methods for the UV-vis absorption spectra of recently developed organic photocatalyst molecules. The novelty in our benchmark framework is that it focuses on evaluating the real-world applicability of computational methods and does not penalize errors that do not contribute to spectral shapes. We employ a spectral fitting process where the calculated excitations are convoluted with Gaussians using two parameters for broadening and wavelength scaling. This way, most methods can sufficiently reproduce the experimental spectra, but they differ in how much adjustment they require from the parameters. Overall, the double hybrids (with the notable exception of DSD-BLYP) are the best functionals that offer the highest predictive power as they require practically no scaling. They are exceptionally good in estimating the excitation energies with almost 90 % of the fitted spectra falling into the ±10 % scaling window. This is the same level of accuracy as provided by the STEOM-DLPNO-CCSD correlated wavefunction method. In terms of cost efficiency, M06 emerges as the best functional. It compensates a slightly less consistent performance with lower computational demand and availability in nearly all computational codes. Therefore, we recommend the use of double-hybrid and M06 functionals for UV-vis spectrum prediction of novel organic photocatalysts, and we also highlight that M06 can be used as a black-box method even by those who are non-experts in computational chemistry. The developed protocol and a user-friendly notebook to assist the analysis are available on GitHub.

The quest for atomic structures of microsecond reaction intermediates is at the frontline of modern biochemistry. Currently, there is a clear lack of experimental methods for preparing necessary time-resolved samples. Here, we report the development of a single-turnover technique for nanosecond initiation and suspension of biomolecular reactions with kinetic resolution in the microsecond time domain. Reactions can be started by large temperature-jump or direct mixing and arrested by hyperquenching in liquid cryogen at a target temperature of 77 K. Diverse morphology of nanoscale glassy bodies feature among others thin field-of-view plane sheets that can be used for structure analyses of freeze-trapped macromolecules by transmission electron cryomicroscopy. We also report the ultra-high vacuum sublimation at 77 K – a novel method for concentrating reaction intermediates for structural studies by low-temperature techniques.

The Front Cover shows how X-rays can be used to obtain spatially resolved chemical imaging insight from within an industrial catalytic reactor. Understanding how the microstructure of the active Cu⁰ component in the commercially applicable Cu/ZnO/Al₂O₃(−Cs₂O) low-temperature water-gas shift catalyst evolves under various H₂ partial pressures in the presence/absence of a Cs promoter during thermal activation has been the subject of the present investigation. More information can be found in the Research Article by Daniela M. Farmer et al..

Invited for this month's cover is the group of Andrew M. Beale at the University College London and at the Research Complex at Harwell (UK). The cover picture demonstrates how X-rays can be used to obtain spatially resolved chemical imaging insight from within an industrial catalytic reactor. Understanding how the microstructure of the active Cu⁰ component in the commercially applicable Cu/ZnO/Al₂O₃(−Cs₂O) low-temperature water-gas shift catalyst evolves under various H₂ partial pressures in the presence/absence of a Cs promoter during thermal activation has been the subject of the present investigation. Read the full text of their Research Article at 10.1002/cmtd.202200015.