Chemphyschem最新文献

Catalysts based on nickel(II) ions, due to their high reactivity and easiness of ligand modification, are among the most widely used catalytic systems in the world, with applications in a variety of catalytic processes. Here we present research that led to the synthesis of new nickel(II) complex compounds containing nicotinic and isonicotinic acid ligands. Their catalytic properties have been studied in oligomerization processes of olefins and isocyanides and the obtained oligomers were subjected to qualitative and quantitative analysis to determine their physicochemical properties. The catalytic activity values achieved in the oligomerization of olefins, only in a few cases reached above 100 g·mmol-1·h-1·bar-1. However, the newly obtained catalytic systems showed very high (99%) and moderate (36%) efficiency in the oligomerization of cyclohexyl isocyanide. The conducted studies provide knowledge about the influence of modification of the main ligand and reaction conditions on the values of catalytic activity, process yields, as well as physicochemical properties of the obtained oligomers. Furthermore, it was possible to determine which of the processes carried out using the newly synthesized catalytic systems achieve better results and in which process they should be further used and developed.

Covalent organic frameworks (COFs) based organic electrodes have emerged as promising electrode candidates for the development of next generation alkali metal ion batteries. We have employed density functional theory (DFT) based calculations to investigate the interaction of alkali metal atoms with one redox active, crystalline, experimentally synthesized COF, namely TQBQ, which consists of triquinoxalinylene and benzoquinone units in the skeleton. The electrochemical properties such as average adsorption energy, average voltage and volume change in terms of structure distortion are computed to explore its feasibility as cathode for lithium (Li), sodium (Na) and potassium (K) ion batteries. We show that among three alkali metal atoms (Li, Na and K), the TQBQ-COF would be a better candidate as cathode for potassium ion battery owing to higher average voltage and minimal volume change.

The Cover Feature illustrates the contact and solvent-separated ion pairs present in mixtures of lithium bis(trifluoromethanesulfonyl)imide ([Li][NTf₂]) and triglyme (G3), often called solvate ionic liquids. In their Research Article (DOI: 10.1002/cphc.202400991), R. Ludwig and co-workers relate how they used far infrared spectroscopy to probe cation–anion and cation–triglyme interactions depending on the salt concentration. Molecular dynamics simulations provided a detailed molecular picture of the complexes formed in this promising electrolyte system.

Bismuth ferrite (BiFeO₃) is a multiferroic perovskite material with a narrow band gap (~2.1 eV), demonstrating significant potential as a photocatalyst for environmental remediation and sustainable energy applications. Its photocatalytic capabilities include dye degradation, air purification, wastewater treatment, and hydrogen generation, all driven by its ability to harness visible light. This review critically examines the factors influencing the photocatalytic performance of BiFeO₃ (BFO) and its doped derivatives. Advances in synthesis techniques, such as sol-gel, hydrothermal, and combustion methods, are discussed concerning particle size, crystallinity, and surface modifications. Key strategies, including rare earth element doping, heterostructure formation, and co-catalyst integration, are explored for their role in enhancing charge separation and light absorption, achieving efficiency improvements of over 90 % in some cases. The mechanistic pathways of photocatalysis, with a focus on electron-hole dynamics and radical generation, are analyzed to provide deeper insights into material performance. Despite its potential, challenges such as limited stability and rapid recombination rates persist. This review identifies critical research gaps and proposes directions for optimizing BFO's design and scalability, reinforcing its relevance as a next-generation photocatalyst for addressing global environmental and energy challenges.

The Cover Feature shows the molecular structure of a cyclic dipeptide self-assembling to form a fluid columnar rectangular phase and ambipolar charge carrier mobility in the columnar liquid crystalline phase, which is represented by the beautiful polarizing optical microscopic image in the background. More information can be found in the Research Article by A. S. Achalkumar and co-workers (DOI: 10.1002/cphc.202400980).

In this work, we evaluate the superatomic characteristics of the favorable global minima of electron precise clusters, leading to stable species featuring catalytic reactive sites and inherent aromaticity in both planar and spherical realms. The results show that Ag6Ru exhibits an electron precise 10-electron 1S21Px,y41Dxy,x2-y24 planar superatomic electron shell structure, related to the 1S21P61D10 18-electron structure of the spherical Ag10Ru cluster, involving seven and ten reactive sites. The favorable electronic structure in such related clusters exhibit diatropic ring currents and long-range shielded regions, supporting the respective planar- and three- dimensional aromatic character. Hence, further planar and three-dimensional relationship between electron precise clusters may trigger a fundamental rationalization in finding stable and useful targets for undergoing catalytic activity for reactions such as oxygen reduction reaction, extending similarities between different cluster shapes at certain sizes.

The interaction of diiodine with quinuclidine (QN) and 4-dimethylaminopyridine (DMAP) in solutions with 1:1 molar ratio of reactants at room temperature produced (in essentially quantitative yields) pure charge-transfer QN·I2 adducts and iodine(I) salt [DMAP-I-DMAP]I3, respectively. In comparison, the quantitative formation of pure iodine (I) salt [QN-I-QN]I5 was observed for the room-temperature reactions of QN with a 50% excess of I2, and the charge-transfer adducts of I2 with DMAP (and other pyridines) were formed when reactions were carried out at low temperatures. Computational analysis related the switch from the formation of charge-transfer adducts to iodine(I) complexes in these systems to the strength of the halogen bonding of diiodine to the N-donor bases. It shows that while the halogen bonded adducts represent critical intermediates in the formation of iodine(I) complexes, exceedingly strong halogen bonding between diiodine and the base prevent any subsequent transformations. In other words, while halogen bonding usually facilitates electron and halogen transfer, the halogen-bonded complexes may serve as "black holes" hindering any follow-up processes if this intermolecular interaction is too strong.

The Front Cover shows unconventional photoelectron emission with a train of ultraviolet femtosecond laser pulses in the electron gun of an ultrafast electron microscope. Off-axis photoemission from the aperture surface of the electron gun leads to surprising behavior of the photoelectron collection efficiency and of the statistical temporal spread of the ultrashort electron packets. More information can be found in the Research Article by S. A. Willis and D. J. Flannigan (DOI: 10.1002/cphc.202401032). Illustration by Rick Simonson, Science Lab Studios, Inc.

Disulfide hydrogels, derived from cysteine-based redox systems, exhibit active self-assembly properties driven by reversible disulfide bond formation, making them a versatile platform for dynamic material design. Detailed cryogenic electron microscopy (cryo-EM) analysis revealed a consistent fiber diameter of 5.4 nm for individual fibers. Using cryo-EM-informed radial positional restraints, all-atom molecular dynamics (MD) simulations were employed to reproduce fibers with dimensions closely matching experimental observations, validated further through simulated cryo-EM images. The MD simulations revealed that the disulfide gelator (CSSC) predominantly adopts an open conformation, with hydrogen bonds emerging as the key intermolecular force stabilizing the fibers. Notably, intermolecular interactions were found to be higher at 70% conversion to the disulfide gelator compared to 100%, comparable with past unrestrained simulations. Water molecules and solute-water hydrogen bonds are present throughout the fiber, indicating that the fiber remains hydrated. These findings underscore the potential role of the thiol precursor CSH in stabilizing the transient phase and highlight the importance of CSH-CSSC interplay. This study provides novel insights into molecular mechanisms governing self-assembly and offers strategies for designing tunable materials through controlled assembly conditions.

This work presents a systematic study of the electronic response and physico-chemical characteristics from hydrothermally treated organic carbon sources (banana peels and cocoa husks). Both samples are exposed to 150 °C and 210 °C for 2, 4, and 6 hours. X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and conductivity measurements are used to describe the electronic properties for each organic carbon source. A multicategorical statistical optimization model let us to identify the best dielectric performance considering: a) temperature treatment, b) exposure time, c) frequency, and d) the organic carbon source. Our results indicate that cocoa husk hydrothermally treated samples (CHH) exhibited the best dielectric response, originating from high carboxyl concentrations or diamond-like carbon structures at 150°C for 6 and 2 hours. In contrast, banana peel hydrothermally treated samples (BPH) are good conductors in comparison to CHH, due to low carboxylation or highly graphitization. This study provides valuable insights into the fundamental structure of lignocellulosic carbon sources that can aid in the development of energy storage and microwave technologies by transforming agricultural residues into high-value electronic materials.