A porous crystal family has been explored as alternatives of Nafion films exhibiting super‐proton conductivities of ≥10−2 S cm−1. Here, the proton‐conduction natures of a solution‐processed film of ...nanoparticles (NPs) have been studied and compared to those of a Nafion film. A mono‐particle film of Prussian‐blue NPs is spontaneously formed on a self‐assembled monolayer substrate by a one‐step solution process. A low‐temperature heating process of the densely packed, pinhole‐free mono‐particle NP film enables a maximum 105‐fold enhancement of proton conductivity, reaching ca. 10−1 S cm−1. The apparent highest conductivity, compared to previously reported data of the porous crystal family, remains constant against humidity changes by an improved water‐retention ability of the film. In our proposed mechanism, the high‐performing solution‐processed NP film suggests that heating leads to the self‐restoration of hydrogen‐bonding networks throughout their innumerable grain boundaries.
A densely packed, pinhole‐free mono‐particle film of Prussian blue (PB) nanoparticles is formed on a substrate. Low‐temperature heating of the film leads to an up to 105‐fold enhancement of proton conductivity, reaching circa 10−1 S cm−1. The high‐performing solution‐processed film suggests that heating enables the self‐restoration of hydrogen‐bonding networks throughout their innumerable grain boundaries.
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To establish a strategy for designing porous coordination polymers (PCPs) for ammonia capture, the first systematic study on the stability of PCPs against ammonia was conducted. Various types of PCPs ...were investigated by comparing their powder XRD patterns before and after treatment with ammonia. Among the PCPs tested, ZIF‐8, MIL‐53(Al), Al‐BTB, MOF‐76(M) (M=Y or Yb), MIL‐101(Cr), and MOF‐74(Mg) were stable up to 350 °C under an ammonia atmosphere at ambient pressure. The origin of the stability of PCPs is discussed from the viewpoint of their components, metal cations, and organic linkers. Furthermore, adsorption isotherm measurements show that the adsorptive behavior of PCPs is independent of their stability.
Poised to react: The stability of porous coordination polymers (PCPs) against ammonia was systematically studied to establish a strategy to design PCPs for ammonia capture (see figure). The origin of the stability of PCPs is discussed from the viewpoint of their components, metal cations and organic linkers. Adsorption isotherm measurements showed that the adsorptive behavior of PCPs was independent of their stability.
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Trans‐p‐methoxy arylazopyrazole spontaneously forms non‐centrosymmetric polar crystals, which reversibly undergo liquefaction upon photoisomerization to the cis‐isomer. This liquid cis‐isomer has a ...large electric dipole moment and is highly soluble in water (solubility up to ≈58 mM), which is remarkably higher than that of the trans‐isomer (690 μM). Vis‐light illumination of the aqueous cis‐isomer generates macroscopically oriented, non‐centrosymmetric crystals at the air–water interface. Polar crystals are also formed in sandwich glass cells (spacing, 20 μm) upon photo‐induced crystallization of the liquid cis‐isomer. The trans‐crystals thus formed showed second harmonic generation (SHG) whose intensity is switched on/off in response to the photo‐induced phase transition.
Macroscopically oriented, large polar crystalline films were fabricated at the air–water interface by photoisomerization of a cis‐arylazopyrazole derivative dissolved in the aqueous phase. The trans‐film formed on the solid substrate showed reversible photo‐induced phase changes between the polar crystal and liquid phase, which lead to an on/off photo‐switching of the second‐harmonic‐generation intensity.
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The synthesis, structural, and photophysical investigations of CuI complexes with a disilanylene-bridged bispyridine ligand 1 are herein presented. Dinuclear (2) and ladder-like (3) octanuclear ...copper(I) complexes were straightforwardly prepared by exactly controlling the ratio of CuI/ligand 1. Single-crystal X-ray analysis confirmed that dinuclear complex 2 had no apparent π…π stacking whereas octanuclear complex 3 had π…π stacking in the crystal packing. In the solid state, the complexes display yellow-green (λem = 519 nm, Φ = 0.60, τ = 11 µs, 2) and blue (λem = 478 nm, Φ = 0.04, τ = 2.6 µs, 3) phosphorescence, respectively. The density functional theory calculations validate the differences in their optical properties. The difference in the luminescence efficiency between 2 and 3 is attributed to the presence of π…π stacking and the different luminescence processes.
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Abstract
We demonstrate thermo-electrochemical (TEC) conversion using a biocompatible redox couple of lactic acid and pyruvic acid on earth-abundant TiO
2
. The TEC cell exhibited a positive Seebeck ...coefficient of 1.40 mV K
−1
. DFT calculations figured out that the adsorption of intermediate species and protons on TiO
2
controls both the redox reaction and current polarity.
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Crystalline particles of a microporous, robust, and chiral metal–organic framework (MOF) were synthesized and their enantiomer excess (ee) was visualized for each microparticle by CD imaging. Labtb, ...a thermally and chemically robust MOF, was employed in this study because it shows a chiral space group. Although Labtb has been obtained as a racemic conglomerate, enantioselective synthesis of Labtb was achieved via a chiral precursor complex consisting of lanthanum and homochiral phenylalanine. Methyl orange (MO) was introduced into the micropores of chiral Labtb, which showed a strong induced CD signal for the absorption band of MO chromophores. High ee of the chiral Labtb was revealed by microscopic CD observation at the particle‐level. This result provides a facile way to obtain a robust MOF that has chiral nanospace.
MOFs: A chiral Labtb was obtained by an amino acid complex as a precursor, and its enantiomer excess at a particular level was visualized by circular dichroism imaging (see scheme).
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The synthesis of a new ionic plastic crystal, tetraethylammonium-d 20 d-10-camphorsulfonate, is reported. The crystal has three solid phases, the structures of which were determined by ...single-crystal X-ray diffraction (XRD). XRD analysis revealed a phase transition from nonpolar space group P21212 to polar space group P21 with increasing temperature. The dynamics of the d-10-camphorsulfonate anion and the tetraethylammonium-d 20 cation was investigated by variable-temperature 1H and 2H solid-state NMR spectroscopy. The anion showed swing motion in high-temperature phases, which is in good agreement with the disorder observed in XRD analysis. The cation showed uniaxial rotation even in the low-temperature phase. The rotation axis of the tetrahedral structure showed a transition from the two-fold axis to the three-fold axis with the phase transition.
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A σ–π extended aryldisilane, comprising a thienopyrazine group as an acceptor fragment and phenothiazine groups as the donor moiety, has been prepared through the introduction of two Si−Si bridges ...(compound 1). X‐ray diffraction analysis determined the crystal structure of 1, and experimental and theoretical approaches investigated its optical properties. Solvatochromic studies revealed the dual emission of 1 in all solvents tested. Compound 1 also exhibited fluorescence in the solid state upon excitation with a hand‐held UV lamp, as well as mechanochromic luminescent properties. The packing mode in the crystal structure, variation of phenothiazine conformation, morphological changes between crystalline and amorphous phases are the major factors showing reversible fluorescence under external stimuli. A theoretical conformer study found that 1 exists in distinct conformational groups differing in Gibbs free energy by less than 3 kcal mol−1. The conformer in the crystalline state of 1 can promote the complete separation of the HOMO and LUMO between the phenothiazine donor and the thienopyrazine acceptor, linked by the disilane linker. HOMO–LUMO energy transition in the crystalline state is forbidden due to the lack of frontier orbital overlap. Crystalline state emission showed LUMO → HOMO−1 transition (locally excited (LE) state). In the amorphous state, the partial presence of quasi‐axial conformers allows intramolecular charge‐transfer type emission via energy transfer from dominant quasi‐equatorial conformers. The strategy proposed in this work provides important guidance for developing stimuli‐responsive materials with controlled excited states.
A σ–π extended aryldisilane comprising a thienopyrazine group as acceptor fragment and a phenothiazine group as donor moiety was prepared. The compound exhibits fluorescence in the solid state upon UV excitation and mechanochromic luminescent properties.
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Early rejection is a critical issue to be overcome to achieve successful islet transplantation. NLRP3 inflammasome is a protein complex that mediates the maturation of pro-interleukin (IL)-1β and ...pro-IL-18 to IL-1β and IL-18, respectively, which induce cellular death. Here, we investigated the impact of NLRP3 inflammasome and the effect of its inhibition by MCC950 in a rodent model of islet transplantation. We assessed the therapeutic effects of MCC950, a specific inhibitor of NLRP3 inflammasome, on gene expression, islet survival ratio and viability, and islet transplantation in mice. NLRP3 inflammasome-related gene (Nlrp3 and Il1b) expression was upregulated in islets stimulated with proinflammatory cytokines and suppressed when incubated with MCC950. Survival ratio and viability of incubated islets were reduced by cytokine stimulation and improved by MCC950. Regarding islet transplantation, the number of apoptotic cells in transplanted islets was reduced by MCC950. Furthermore, the expression of IL-1β in transplanted islets, migration of macrophages around islets, and fluctuation of blood glucose levels were suppressed by MCC950. Our study revealed that NLRP3 inflammasome worsened the therapeutic outcomes of islet transplantation and that MCC950 administration improved glycaemic control in syngeneic mice that underwent islet transplantation by inhibiting inflammation, which suppressed islet death.
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