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Quantitative Measurement of Molecular Permeability to a Synthetic Bacterial Microcompartment Shell System
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Discrete Open-Shell Tris(bipyridinium radical cationic) Inclusion Complexes in the Solid State
In the solid state the properties of organic radicals depend heavily on radical-radical interactions that are influenced by the superstructure of the crystalline phase. Here, we report the synthesis and characterization of a substituted tetracationic cyclophane, cyclobis(paraquat-p-1,4- dimethoxyphenylene), and outline how its bisradical dicationic redox state associates with the methyl viologen radical cation (MV •+ ) to give a trisradical tricationic inclusion complex. The (super)structures of the reduced cyclophane and this 1:1 complex in the solid-state deviate from the analogous (super)structures observed for the reduced state of cyclobis(paraquat-p-phenylene) and that of its trisradical tricationic complex. Titration experiments with a range of guests reveal that the methoxy substituents on the para-xylenyl do not influence significantly of the binding affinity of the cyclophane for small neutral guests, whereas the affinity decreases by an order of magnitude for larger radical cationic guests such as MV •+ . X-Ray diffraction reveals that the solid- state structures of the tricationic trisradical complexes to be a discrete entity with weak intermolecular orbital overlap between the neighboring complexes. Transient nutation EPR experiment and DFT calculations confirm that the complex has a doublet spin configuration in the ground state as a result of the strong orbital overlap within the complex, while the quartet-state spin configuration is higher in energy and so is inaccessible at ambient temperature. The superconducting quantum interference device (SQUID) measurement reveals that trisradical tricationic complexes interact antiferromagnetically (J/k = - 2.33 K) and form a 1D Heisenberg antiferromagnetic chain along the a-axis in the crystal. Furthermore, these results offer new insights into the design and synthesis of organic magnetic materials based on host-guest inclusion complexes.
How Radical Are ?Radical? Photocatalysts? A Closed-Shell Meisenheimer Complex Is Identified as a Sup
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Signatures of the Bromine Atom and Open-Shell Spin Coupling in the X-ray Spectrum of the Bromobenzene Cation
Tabletop X-ray spectroscopy measurements at the carbon K-edge complemented by ab initio calculations are used to investigate the influence of the bromine atom on the carbon core–valence transitions in the bromobenzene cation (BrBz + ). The electronic ground state of the cation is prepared by resonance-enhanced two-photon ionization of neutral bromobenzene (BrBz) and probed by X-rays produced by high-harmonic generation (HHG). Replacing one of the hydrogen atoms in benzene with a bromine atom shifts the transition from the 1s C* orbital of the carbon atom (C*) bonded to bromine by ~1 eV to higher energy in the X-ray spectrum compared to the other carbon atoms (C). Moreover, in BrBz + , the X-ray spectrum is dominated by two relatively intense transitions, 1s C →π* and 1s C* →σ*(C*–Br), where the second transition is enhanced relative to the neutral BrBz. In addition, a doublet peak shape for these two transitions is observed in the experiment. The 1s C →π* doublet peak shape arises due to the spin coupling of the unpaired electron in the partially vacant π orbital (from ionization) with the two other unpaired electrons resulting from the transition from the 1s C core orbital to the fully vacant π* orbitals. Here, the 1s C* →σ* doublet peak shape results from several transitions involving σ* and vibrational C*–Br mode activations following the UV ionization, which demonstrates the impact of the C*–Br bond length on the core–valence transition as well as on the relaxation geometry of BrBz + .
Composition-Defined Optical Properties and the Direct-to-Indirect Transition in Core–Shell In 1– x Ga x P/ZnS Colloidal Quantum Dots
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Second-Shell N Dopants Regulate Acidic O 2 Reduction Pathways on Isolated Pt Sites
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Direct 12-Electron Oxidation of Ethanol on a Ternary Au(core)-PtIr(shell) Electrocatalyst
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Quantum chemical calculations for over 200,000 organic radical species and 40,000 associated closed-shell molecules
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Plasma screening in mid-charged ions observed by K-shell line emission
Dense plasma environment affects the electronic structure of ions via variations of the microscopic electrical fields, also known as plasma screening. This effect can be either estimated by simplified analytical models, or by computationally expensive and to date unverified numerical calculations. We have experimentally quantified plasma screening from the energy shifts of the bound-bound transitions in matter driven by the x-ray free electron laser (XFEL). This was enabled by identification of detailed electronic configurations of the observed Kα, Kβ and Kγ lines. This work paves the way for improving plasma screening models including connected effects like ionization potential depression and continuum lowering, which will advance the understanding of atomic physics in the Warm Dense Matter regime.
Reversible loss of core-shell structure for Ni-Au bimetallic nanoparticles during CO[subscript 2] hydrogenation
Abstract not provided
Core–shell nanostructures: perspectives towards drug delivery applications
Nanosystems have shown encouraging outcomes and substantial progress in the areas of drug delivery and biomedical applications.
Nanoscale core–shell structure and recrystallization of swift heavy ion tracks in SrTiO 3
It is widely accepted that the interaction of swift heavy ions with many complex oxides is predominantly governed by the electronic energy loss that gives rise to nanoscale amorphous ion tracks along the penetration direction.