Multi-target drug design of anti-Alzheimer’s disease based on tacrine.

: Alzheimer's disease (AD) is a progressive neurodegenerative disease with concealed onset, which is characterized by damage of cholinergic system, deposition and accumulation of β-amyloid protein (Aβ) and Neurofibrillary tangles. Because cholinergic system plays a key role in the process of brain memory, cholinergic system has become one of the important targets in anti-AD research. In view of the complicated pathological characteristics of AD, the multi-target directed ligands (MTDLs) that can act on multiple targetsis considered to be an effective treatment strategy at present. Tacrine, as the first acetylcholinesterase (AChE) inhibitor, has been discontinued because of its hepatotoxicity, but its core structure is simple and easy to modify. By using tacrine to target the catalytic active site (CAS), the tacrine-based MTDLs can act on both CAS and peripheral anion site (PAS) of AChE so as to serve as a dual-site AChE inhibitor. Additionally, the tacrine-based MTDLs can also be designed on the basis of other theories of AD, for example, introducing functional moieties to modulate the formation of β-amyloid (Aβ), oxidation resistance or metal chelation. In this paper, the research progress of tacrine-based MTDLs is summarized.

FeBiS2Cl – A new iron-containing member of the MPnQ2X family

The new sulfochloride FeBiS2Cl is obtained as a black powder following a mechanochemical synthesis procedure. The product crystallizes in the orthorhombic space group Cmcm (no. 63) with lattice parameters a = 3.82142(7), b = 12.2850(2) and c = 9.2911(2) Å. While the iron atom has an octahedral coordination environment, the bismuth atom is coordinated in the form of a bicapped trigonal prism. Both cation polyhedra form alternating layers, for iron built up of corner sharing octahedra along the c axis and edge sharing ones along the a axis. The bismuth polyhedra are connected through shared faces along the c axis and common edges along the a axis. Because of the distribution of sulfur and chlorine on a mixed anion site, the bismuth atoms occupy split positions. Experimental observations are supported by theoretical calculations.

On the Local Charge Inhomogeneity and Lithium Distribution in the Superionic Argyrodites Li6PS5X (X = Cl, Br, I)

The lithium-argyrodites Li₆PS₅<i>X</i> (<i>X</i> = Cl, Br, I) exhibit high lithium-ion conductivities, making them promising candidates for use in solid-state batteries. These solid electrolytes can show considerable substitutional <i>X</i>⁻/S²⁻ anion-disorder, with greater disorder typically correlated with higher lithium-ion conductivities. The atomic-scale effects of this anion site-disorder within the host lattice—in particular how lattice disorder modulates the lithium substructure—are not well understood. Here, we characterize the lithium substructure in Li₆PS₅<i>X</i> (<i>X </i>= Cl, Br, I) as a function of temperature and anion site-disorder, using Rietveld refinements against temperature-dependent neutron diffraction data. Analysis of these high-resolution diffraction data reveals an additional lithium position previously unreported for Li₆PS₅<i>X</i>argyrodites, suggesting that the lithium conduction pathway in these materials differs from the most common model proposed in earlier studies. Analysis of the Li⁺ positions and their radial distributions reveals that greater inhomogeneityof the local anionic charge, due to <i>X</i>⁻/S²⁻ site-disorder, is associated with more spatially-diffuse lithium distributions. This observed coupling of site-disorder and lithium distribution provides a possible explanation for the enhanced lithium transport in anion-disordered lithium argyrodites, and highlights the complex interplay between anion configuration and lithium substructure in this family of superionic conductors.

On the Local Charge Inhomogeneity and Lithium Distribution in the Superionic Argyrodites Li6PS5X (X = Cl, Br, I)

The lithium-argyrodites Li₆PS₅<i>X</i> (<i>X</i> = Cl, Br, I) exhibit high lithium-ion conductivities, making them promising candidates for use in solid-state batteries. These solid electrolytes can show considerable substitutional <i>X</i>⁻/S²⁻ anion-disorder, with greater disorder typically correlated with higher lithium-ion conductivities. The atomic-scale effects of this anion site-disorder within the host lattice—in particular how lattice disorder modulates the lithium substructure—are not well understood. Here, we characterize the lithium substructure in Li₆PS₅<i>X</i> (<i>X </i>= Cl, Br, I) as a function of temperature and anion site-disorder, using Rietveld refinements against temperature-dependent neutron diffraction data. Analysis of these high-resolution diffraction data reveals an additional lithium position previously unreported for Li₆PS₅<i>X</i>argyrodites, suggesting that the lithium conduction pathway in these materials differs from the most common model proposed in earlier studies. Analysis of the Li⁺ positions and their radial distributions reveals that greater inhomogeneityof the local anionic charge, due to <i>X</i>⁻/S²⁻ site-disorder, is associated with more spatially-diffuse lithium distributions. This observed coupling of site-disorder and lithium distribution provides a possible explanation for the enhanced lithium transport in anion-disordered lithium argyrodites, and highlights the complex interplay between anion configuration and lithium substructure in this family of superionic conductors.

On the Local Charge Inhomogeneity and Lithium Distribution in the Superionic Argyrodites Li6PS5X (X = Cl, Br, I)

The lithium-argyrodites Li₆PS₅<i>X</i> (<i>X</i> = Cl, Br, I) exhibit high lithium-ion conductivities, making them promising candidates for use in solid-state batteries. These solid electrolytes can show considerable substitutional <i>X</i>⁻/S²⁻ anion-disorder, with greater disorder typically correlated with higher lithium-ion conductivities. The atomic-scale effects of this anion site-disorder within the host lattice—in particular how lattice disorder modulates the lithium substructure—are not well understood. Here, we characterize the lithium substructure in Li₆PS₅<i>X</i> (<i>X </i>= Cl, Br, I) as a function of temperature and anion site-disorder, using Rietveld refinements against temperature-dependent neutron diffraction data. Analysis of these high-resolution diffraction data reveals an additional lithium position previously unreported for Li₆PS₅<i>X</i>argyrodites, suggesting that the lithium conduction pathway in these materials differs from the most common model proposed in earlier studies. Analysis of the Li⁺ positions and their radial distributions reveals that greater inhomogeneityof the local anionic charge, due to <i>X</i>⁻/S²⁻ site-disorder, is associated with more spatially-diffuse lithium distributions. This observed coupling of site-disorder and lithium distribution provides a possible explanation for the enhanced lithium transport in anion-disordered lithium argyrodites, and highlights the complex interplay between anion configuration and lithium substructure in this family of superionic conductors.

Reactively Sputtered Sb-GaN Films and its Hetero-Junction Diode: The Exploration of the n-to-p Transition

Sb anion-substituted gallium nitride films were fabricated by radio frequency reactive sputtering with single Sb-containing cermet targets with different Sb contents under Ar/N2 atmosphere. n-type GaN films with electron concentration of (1.40 ± 0.1) × 1017 cm−3 inverted to p-type Sb-GaN with hole concentration of (5.50 ± 0.3) × 1017 cm−3. The bandgap energy of Sb anion-added Sb-GaN films decreased from 3.20 to 2.72 eV with increasing Sb concentration. The formation of p-type Sb-GaN is attributed to the formation of Ga vacancy at higher Sb concentration. The coexistence of Sb at the Ga cation site and N anion site is an interesting and important result, as GaNSb had been well developed for highly mismatched alloys. The hetero-junction with p-type Sb-GaN/n-Si diodes was all formed by radio frequency (RF) reactive sputtering technology. The electrical characteristics of Sb-GaN diode devices were investigated from −20 to 20 V at room temperature (RT).

Reactions of a distonic peroxyl radical anion influenced by SOMO–HOMO conversion: an example of anion-directed channel switching

Deprotonation of a remote site in a peroxyl radical energetically buries the singly occupied molecular orbital, suppressing radical-driven oxidation and promoting reactions involving the anion site.

A Breakthrough Application of a Cross-Linked Polystyrene Anion-Exchange Membrane for a Hydrogencarbonate Ion-Selective Electrode

Polystyrene cross-linked with divinylbenzene and functionalized by a quaternary ammonium cation anion site is used as the membrane of a hydrogencarbonate (i.e., bicarbonate) ion-selective electrode. The polystyrene matrix membrane improves the selectivity towards interfering lipophilic ions in comparison to previously described polyvinyl chloride membranes. The reason for this behaviour is sought in coupled ion-exchange and pore-diffusion processes in the membrane and the resulting kinetic discrimination of interfering ions. The electrode is successfully used for determination of bicarbonates in mineral drinking waters. The simplex method is employed to refine the analytical outcome.