BK Channel Gating Mechanisms: Progresses Toward a Better Understanding of Variants Linked Neurological Diseases

The large conductance Ca2+-activated potassium (BK) channel is activated by both membrane potential depolarization and intracellular Ca2+ with distinct mechanisms. Neural physiology is sensitive to the function of BK channels, which is shown by the discoveries of neurological disorders that are associated with BK channel mutations. This article reviews the molecular mechanisms of BK channel activation in response to voltage and Ca2+ binding, including the recent progress since the publication of the atomistic structure of the whole BK channel protein, and the neurological disorders associated with BK channel mutations. These results demonstrate the unique mechanisms of BK channel activation and that these mechanisms are important factors in linking BK channel mutations to neurological disorders.

Acidic Stabilization of the Dual-Aromatic Heterocyclic Anions

Recently, we discovered that the delocalization of nitrogen lone-pair electrons (NLPEs) in five-membered nitrogen heterocycles created a second σ-aromaticity in addition to the prototypical π-aromaticity. Such dual-aromatic compounds, such as the pentazole anion, were proved to have distinct chemistry in comparison to traditional π-aromatics, such as benzene, and were surprisingly unstable, susceptible to electrophilic attack, and relatively difficult to obtain. The dual-aromatics are basic in nature, but prefer not to be protonated when confronting more than three hydronium/ammonium ions, which violates common sense understanding of acid−base neutralization for a reason that is unclear. Here, we carried out 63 test simulations to explore the stability and reactivity of three basic heterocycle anions (pentazole anion N5¯, tetrazole anion N4C1H1¯, and 1,2,4-triazole anion N3C2H2¯) in four types of solvents (acidic ions, H3O+ and NH4+, polar organics, THF, and neutral organics, benzene) with different acidities and concentrations. By quantum mechanical calculations of the electron density, atomistic structure, interatomic interactions, molecular orbital, magnetic shielding, and energetics, we confirmed the presence of dual aromaticity in the heterocyclic anions, and discovered their reactivity to be a competition between their basicity and dual aromaticity. Interestingly, when the acidic ions H3O+/NH4+ are three times more in number than the basic heterocyclic anions, the anions turn to violate acid−base neutralization and remain unprotonated, and the surrounding acidic ions start to show a significant stabilization effect on the studied heterocyclic anions. This work brings new knowledge to nitrogen aromatics and the finding is expected to be adaptable for other pnictogen five-membered ring systems.

Mixed hierarchical local structure in a disordered metal–organic framework

Amorphous metal–organic frameworks (MOFs) are an emerging class of materials. However, their structural characterisation represents a significant challenge. Fe-BTC, and the commercial equivalent Basolite® F300, are MOFs with incredibly diverse catalytic ability, yet their disordered structures remain poorly understood. Here, we use advanced electron microscopy to identify a nanocomposite structure of Fe-BTC where nanocrystalline domains are embedded within an amorphous matrix, whilst synchrotron total scattering measurements reveal the extent of local atomic order within Fe-BTC. We use a polymerisation-based algorithm to generate an atomistic structure for Fe-BTC, the first example of this methodology applied to the amorphous MOF field outside the well-studied zeolitic imidazolate framework family. This demonstrates the applicability of this computational approach towards the modelling of other amorphous MOF systems with potential generality towards all MOF chemistries and connectivities. We find that the structures of Fe-BTC and Basolite® F300 can be represented by models containing a mixture of short- and medium-range order with a greater proportion of medium-range order in Basolite® F300 than in Fe-BTC. We conclude by discussing how our approach may allow for high-throughput computational discovery of functional, amorphous MOFs.

In Search of the Active Sites for the Selective Catalytic Reduction on Tungsten-Doped Vanadia Monolayer Catalysts supported by TiO2

Tungsten-doped vanadia-based catalysts supported on anatase TiO₂ are used to reduce hazardous NO emissions through the selective catalytic reduction of ammonia, but their exact atomistic structure is still largely unknown. In this computational study, the atomistic structure of mixed tungsta-vanadia monolayers on TiO₂ support under typical operating conditions has been addressed by periodic density functional theory calculations. The chemical environment has been taken into account in a grand-canonical approach. We evaluate the stable catalyst structures as a function of the oxygen chemical potential and vanadium and tungsten concentrations. Thus we determine structural motifs of tungsta-vanadia/TiO₂ catalysts that are stable under operating conditions. Furthermore, we identify active sites that promise high catalytic activity for the selective catalytic reduction by ammonia. Our calculations reveal the critical role of the stoichiometry of the tungsta-vanadia layers with respect to their catalytic activity in the selective catalytic reduction.

In Search of the Active Sites for the Selective Catalytic Reduction on Tungsten-Doped Vanadia Monolayer Catalysts supported by TiO2

Tungsten-doped vanadia-based catalysts supported on anatase TiO₂ are used to reduce hazardous NO emissions through the selective catalytic reduction of ammonia, but their exact atomistic structure is still largely unknown. In this computational study, the atomistic structure of mixed tungsta-vanadia monolayers on TiO₂ support under typical operating conditions has been addressed by periodic density functional theory calculations. The chemical environment has been taken into account in a grand-canonical approach. We evaluate the stable catalyst structures as a function of the oxygen chemical potential and vanadium and tungsten concentrations. Thus we determine structural motifs of tungsta-vanadia/TiO₂ catalysts that are stable under operating conditions. Furthermore, we identify active sites that promise high catalytic activity for the selective catalytic reduction by ammonia. Our calculations reveal the critical role of the stoichiometry of the tungsta-vanadia layers with respect to their catalytic activity in the selective catalytic reduction.

Role of the Binding Motifs in the Energy Level Alignment and Conductance of Amine-Gold Linked Molecular Junctions within DFT and DFT + Σ

We investigate, using density functional theory (DFT), the electronic and conducting properties of benzenediamine connected to gold electrodes via different tip structures. We examine a series of binding motifs to the electrodes and calculate the junction spectral properties. We consider corrections to the position of molecular resonances at the junction and discuss different approaches to the calculation of these shifts. We relate the magnitude of these corrections to resonance energies to the atomistic structure of the tip. Benzenediamine DFT-based transmission spectra can be well approximated by a Lorentzian model involving only the highest occupied molecular orbital (HOMO). We show how benzenediamine calculated conductance values in quantitative agreement with previous experiments can be achieved from the combination of DFT-based spectra and corrections to the DFT-based HOMO energy and an accessible Lorentzian model.

Mixed Hierarchical Local Structure in a Disordered Metal–Organic Framework

Amorphous metal–organic frameworks (MOFs) are an emerging class of materials. However, their structural characterisation represents a significant challenge. Fe‑BTC, and the commercial equivalent Basolite® F300, are MOFs with incredibly diverse catalytic ability, yet their disordered structures remain poorly understood. Here, we use advanced electron microscopy to identify a nanocomposite structure of Fe‑BTC where nanocrystalline domains are embedded within an amorphous matrix, whilst synchrotron total scattering measurements reveal the extent of local atomic order within Fe‑BTC. We use a polymerisation-based algorithm to generate an atomistic structure for Fe-BTC, the first example of this methodology applied to the amorphous MOF field outside the well-studied zeolitic imidazolate framework family. This demonstrates the applicability of this computational approach towards the modelling of other amorphous MOF systems with potential generality towards all MOF chemistries and connectivities. We find that the structures of Fe-BTC and Basolite® F300 can be represented by models containing a mixture of short- and medium-range order with a greater proportion of medium-range order in Basolite® F300 than in Fe-BTC. We conclude by discussing how our approach may allow for high-throughput computational discovery of functional, amorphous MOFs.

Mixed Hierarchical Local Structure in a Disordered Metal–Organic Framework

Amorphous metal–organic frameworks (MOFs) are an emerging class of materials. However, their structural characterisation represents a significant challenge. Fe‑BTC, and the commercial equivalent Basolite® F300, are MOFs with incredibly diverse catalytic ability, yet their disordered structures remain poorly understood. Here, we use advanced electron microscopy to identify a nanocomposite structure of Fe‑BTC where nanocrystalline domains are embedded within an amorphous matrix, whilst synchrotron total scattering measurements reveal the extent of local atomic order within Fe‑BTC. We use a polymerisation-based algorithm to generate an atomistic structure for Fe-BTC, the first example of this methodology applied to the amorphous MOF field outside the well-studied zeolitic imidazolate framework family. This demonstrates the applicability of this computational approach towards the modelling of other amorphous MOF systems with potential generality towards all MOF chemistries and connectivities. We find that the structures of Fe-BTC and Basolite® F300 can be represented by models containing a mixture of short- and medium-range order with a greater proportion of medium-range order in Basolite® F300 than in Fe-BTC. We conclude by discussing how our approach may allow for high-throughput computational discovery of functional, amorphous MOFs.