Toward Benchmark-Quality Predictions for 3d Transition Metal Electrocatalysts: A Comparison of CCSD(T) and ph-AFQMC.

Generating accurate ionization energies for transition metal complexes is an important step toward the accurate computational description of their electrocatalytic reactions. Benchmark-quality data is required for testing existing theoretical methods and developing new ones but is complicated to obtain for many transition metal compounds due to the potential presence of both strong dynamical and static electron correlation. In this regime, it is questionable whether the so-called gold standard, coupled cluster with singles, doubles, and perturbative triples (CCSD(T)), provides the desired level of accuracy─roughly 1-3 kcal/mol.

Magnesium Ion-Driven Folding and Conformational Switching Kinetics of Tetracycline Binding Aptamer: Implications for in vivo Riboswitch Engineering.

Engineering in vitro selected RNA aptamers into in vivo functional riboswitches represents a long-standing challenge in molecular biology. The highly specific aptamer domain of the riboswitch undergoes a conformational adjustment in response to ligand sensing, which in turn exerts the regulatory function. Besides essential factors like structural complexity and ligand binding kinetics, the active role of magnesium ions in stabilizing RNA tertiary structures and assisting in ligand binding can be a vital criterion.

An antibiotic from an uncultured bacterium binds to an immutable target.

Antimicrobial resistance is a leading mortality factor worldwide. Here, we report the discovery of clovibactin, an antibiotic isolated from uncultured soil bacteria. Clovibactin efficiently kills drug-resistant Gram-positive bacterial pathogens without detectable resistance.

Stronger Together! Mechanistic Investigation into Synergistic Effects during Homogeneous Carbon Dioxide Hydrogenation Using a Heterobimetallic Catalyst.

A series of group 6 heterobimetallic complexes [M;Ir] (M = Cr, Mo, W) were synthesized and fully characterized, and the catalytic behavior was studied. The heterobimetallic complex [Mo;Ir] () was by far the most active and has shown a considerable synergistic effect, with both metals actively participating in homogeneous carbon dioxide hydrogenation, leading to formate salts. Based on theoretical calculations, the synergistic interaction is due to Pauli repulsion, lowering the transition state and thus enabling higher catalytic activity.

Dispersion Energy-Stabilized Boron and Phosphorus Lewis Pairs.

An isostructural series of boron/phosphorus Lewis pairs was systematically investigated. The association constants of the Lewis pairs were determined at variable temperatures, enabling the extraction of thermodynamic parameters. The stabilization of the Lewis adduct increased with increasing size of the dispersion energy donor groups, although the donor and acceptor properties of the Lewis pairs remained largely unchanged.

Selective Chirality Transfer to the Bis(trifluoromethylsulfonyl)imide Anion of an Ionic Liquid.

Chirality transfer from the chiral molecule (R)-1,2-propylene oxide to the achiral anion of the 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid is observed. The chiral probe selectively affects one part of the binary ionic liquid, i. e.

Observing the Entry Events of a Titanium-Based Photoredox Catalytic Cycle in Real Time.

Titanium-based catalysis in single electron transfer (SET) steps has evolved into a versatile approach for the synthesis of fine chemicals and first attempts have recently been made to enhance its sustainability by merging it with photo-redox (PR) catalysis. Here, we explore the photochemical principles of all-Ti-based SET-PR-catalysis, i.e.

Proton-transfer rate constants for the determination of organic indoor air pollutants by online mass spectrometry.

Proton transfer reaction mass spectrometry (PTR-MS) has become an indispensable analytical tool for indoor related sciences. With high-resolution techniques not only is the online monitoring of the selected ions in the gas phase possible, but also, with some limitations, the identification of substance mixtures without chromatographic separation. The quantification is carried out with the help of kinetic laws, which require knowledge of the conditions in the reaction chamber, the reduced ion moblilities and the reaction rate constant under these conditions.

A new antibiotic from an uncultured bacterium binds to an immutable target.

Antimicrobial resistance is a leading mortality factor worldwide. Here we report the discovery of clovibactin, a new antibiotic, isolated from uncultured soil bacteria. Clovibactin efficiently kills drug-resistant bacterial pathogens without detectable resistance.

Computation of CCSD(T)-Quality NMR Chemical Shifts via Δ-Machine Learning from DFT.

NMR spectroscopy undoubtedly plays a central role in determining molecular structures across different chemical disciplines, and the accurate computational prediction of NMR parameters is highly desirable. In this work, a new Δ-machine learning approach is presented to correct DFT-computed NMR chemical shifts using input features from the calculation and in addition highly accurate reference data at the CCSD(T)/pcSseg-2 level of theory with a basis set extrapolation scheme. The model is trained on a data set containing 1000 optimized and geometrically distorted structures of small organic molecules comprising most elements of the first three periods and containing data for 7090 H and 4230 C NMR chemical shifts.

Lipid oxidation controls peptide self-assembly near membranes through a surface attraction mechanism.

The self-assembly of peptides into supramolecular structures has been linked to neurodegenerative diseases but has also been observed in functional roles. Peptides are physiologically exposed to crowded environments of biomacromolecules, and particularly cellular membrane lipids. Previous research has shown that membranes can both accelerate and inhibit peptide self-assembly.

Structure and function of the metagenomic plastic-degrading polyester hydrolase PHL7 bound to its product.

The recently discovered metagenomic-derived polyester hydrolase PHL7 is able to efficiently degrade amorphous polyethylene terephthalate (PET) in post-consumer plastic waste. We present the cocrystal structure of this hydrolase with its hydrolysis product terephthalic acid and elucidate the influence of 17 single mutations on the PET-hydrolytic activity and thermal stability of PHL7. The substrate-binding mode of terephthalic acid is similar to that of the thermophilic polyester hydrolase LCC and deviates from the mesophilic IsPETase.

A non-self-consistent tight-binding electronic structure potential in a polarized double-ζ basis set for all spd-block elements up to Z = 86.

Existing semiempirical molecular orbital methods suffer from the usually minimal atomic-orbital (AO) basis set used to simplify the calculations. Here, a completely new and consistently parameterized tight-binding electronic structure Hamiltonian evaluated in a deeply contracted, properly polarized valence double-zeta basis set (vDZP) is described. The inner-shell electrons are accounted for by standard, large-core effective potentials and approximations to them.

Synergistic Catalysis in Heterobimetallic Complexes for Homogeneous Carbon Dioxide Hydrogenation.

Two heterobimetallic Mo,M' complexes (M' = Ir, Rh) were synthesized and fully characterized. Their catalytic activity in homogeneous carbon dioxide hydrogenation to formate was studied. A pronounced synergistic effect between the two metals was found, most notably between Mo and Ir, leading to a fourfold increase in activity compared with a binary mixture of the two monometallic counterparts.

Peptide Self-Assembly into Amyloid Fibrils at Hard and Soft Interfaces-From Corona Formation to Membrane Activity.

Peptides and proteins are exposed to a variety of interfaces in a physiological environment, such as cell membranes, protein nanoparticles (NPs), or viruses. These interfaces have a significant impact on the interaction, self-assembly, and aggregation mechanisms of biomolecular systems. Peptide self-assembly, particularly amyloid fibril formation, is associated with a wide range of functions; however, there is a link with neurodegenerative diseases, such as Alzheimer's disease.

Analysis of Fast Fluorescence Kinetics of a Single Cyanobacterium Trapped in an Optical Microcavity.

Photosynthesis is one the most important biological processes on earth, producing life-giving oxygen, and is the basis for a large variety of plant products. Measurable properties of photosynthesis provide information about its biophysical state, and in turn, the physiological conditions of a photoautotrophic organism. For instance, the chlorophyll fluorescence intensity of an intact photosystem is not constant as in the case of a single fluorescent dye in solution but shows temporal changes related to the quantum yield of the photosystem.

A study on the material properties of novel PEGDA/gelatin hybrid hydrogels polymerized by electron beam irradiation.

Gelatin-based hydrogels are highly desirable biomaterials for use in wound dressing, drug delivery, and extracellular matrix components due to their biocompatibility and biodegradability. However, insufficient and uncontrollable mechanical properties and degradation are the major obstacles to their application in medical materials. Herein, we present a simple but efficient strategy for a novel hydrogel by incorporating the synthetic hydrogel monomer polyethylene glycol diacrylate (PEGDA, offering high mechanical stability) into a biological hydrogel compound (gelatin) to provide stable mechanical properties and biocompatibility at the resulting hybrid hydrogel.

Modulation of Aβ42 Aggregation Kinetics and Pathway by Low-Molecular-Weight Inhibitors.

The aggregation of amyloid-β 42 (Aβ42) is directly related to the pathogenesis of Alzheimer's disease. Here, we have investigated the early stages of the aggregation process, during which most of the cytotoxic species are formed. Aβ42 aggregation kinetics, characterized by the quantification of Aβ42 monomer consumption, were tracked by real-time solution NMR spectroscopy (RT-NMR) allowing the impact that low-molecular-weight (LMW) inhibitors and modulators exert on the aggregation process to be analysed.

Probing a Hydrogen-π Interaction Involving a Trapped Water Molecule in the Solid State.

The detection and characterization of trapped water molecules in chemical entities and biomacromolecules remains a challenging task for solid materials. We herein present proton-detected solid-state Nuclear Magnetic Resonance (NMR) experiments at 100 kHz magic-angle spinning and at high static magnetic-field strengths (28.2 T) enabling the detection of a single water molecule fixed in the calix[4]arene cavity of a lanthanide complex by a combination of three types of non-covalent interactions.

Formation of heterogeneous clusters in superfluid helium nanodroplets: phthalocyanine and water.

Clusters consisting of a single phthalocyanine molecule and a single water molecule are investigated by means of electronic spectroscopy in superfluid helium droplets. A recent spectroscopic study of those clusters [J. Fischer, F.

Towards Improved Humidity Sensing Nanomaterials via Combined Electron and NH Treatment of Carbon-Rich FEBID Deposits.

Focused Electron Beam Induced Deposition (FEBID) is a unique tool to produce nanoscale materials. The resulting deposits can be used, for instance, as humidity or strain sensors. The humidity sensing concept relies on the fact that FEBID using organometallic precursors often yields deposits which consist of metal nanoparticles embedded in a carbonaceous matrix.

Hybrid Molecular Magnets with Lanthanide- and Countercation-Mediated Interfacial Electron Transfer between Phthalocyanine and Polyoxovanadate.

A series of {V}-nuclearity polyoxovanadate cages covalently functionalized with one or sandwiched by two phthalocyaninato (Pc) lanthanide (Ln) moieties V-O-Ln bonds were prepared and fully characterized for paramagnetic Ln = Sm-Er and diamagnetic Ln = Lu, including Y. The LnPc-functionalized {VO} cages with fully oxidized vanadium centers in the ground state were isolated as (BuN)[HVOCl(LnPc)] and (BuN)[HVOCl(LnPc)] compounds. As corroborated by a combined experimental (EPR, DC and AC SQUID, laser photolysis transient absorption spectroscopy, and electrochemistry) and computational (DFT, MD, and model Hamiltonian approach) methods, the compounds feature intra- and intermolecular electron transfer that is responsible for a partial reduction at V(3d) centers from V to V in the solid state and at high sample concentrations.