A rigid hydrogen‐bonded organic framework (HOF) was constructed from a C3‐symmetric hexatopic carboxylic acid with a hydrophilic 18‐crown‐6‐ether (18C6) component. Despite the flexible macrocyclic ...structure with many conformations, the derivative with three 4,4’‐dicarboxy‐o‐terphenyl moieties in the periphery yielded a rigid layered porous framework through directional intermolecular hydrogen bonding. Interestingly, the HOF possesses 1D channels with bottleneck composed of 18C6 rings. The HOF shows proton conductivity (1.12×10−7 S cm−1) through Grotthuss mechanism (Ea=0.27 eV) under 98 %RH. The present unique water channel structure provides an inspiration to create molecular porous materials.
A porous hydrogen‐bonded framework (HOF) was constructed from a 18‐crown‐6‐ether (18C6) derivative. Although a 18C6 macrocycle is flexible and has many possible conformations, directional intermolecular hydrogen bonds of 4,4′‐dicarboxy‐o‐terphenyl modules in the periphery of the 18C6 allowed to form a rigid HOF with 1D channels with a bottleneck composed of 18C6 rings. The wet HOF shows proton conductivity (1.12×10−7 S cm−1) through a Grotthuss mechanism (Ea=0.27 eV) under 98 %RH.
Molecular ferroelectrics have promising potential as next-generation flexible electronic materials by the advantage of flexibility, structural tunability, and easy processability. However, an ...obstacle in expanding their promising applications is effectively raising the ferroelectric transition temperature (Tc) necessary for practical applications, especially under high-temperature operating conditions. Herein, taking the advantage of a hydroxyl group that could form stronger hydrogen bonds to insert/tune host–guest and guest–guest interactions, we employed the 3-hydroxypyrrolidine cation to construct two new enantiomeric hexagonal perovskite ferroelectrics, (R)-3-OH-(C4H9N)CdCl3 and (S)-3-OH-(C4H9N)CdCl3. Both of them undergo a ferroelectric phase transition from C2221 to P21 with a high Tc of 350 K, which is 110 K and 47 K higher than that of their parent compound (C4H10N)CdCl3 (240 K) and F-substituted analogues (R/S)-3-F-(C4H9N)CdCl3 (303 K), respectively. These findings well demonstrate that, besides the F-substitution strategy, an OH-substitution strategy provides an important and practical way in designing high-Tc ferroelectrics.
•Crystal structures of two molecular metals were obtained at 291 and 150K.•The Ni(III) ions of 1 and 2 form a non-uniform 1D zigzag magnetic chain.•Compound 1 exhibits an interesting characteristic ...of spin-gap.•Compound 2 shows two shows two spin-gap transitions.
Two new molecular metals, 2FBz-2NH2PyNi(mnt)2 (1) and 4FBz-2NH2PyNi(mnt)2 (2) (2FBz-2NH2Py+=1-(2′-fluobenzyl)-2-aminopyridinium, 4FBz-2NH2Py+=1-(4′-fluobenzyl)-2-aminopyridinium mnt2−=maleonitriledithiolate), have been prepared and characterized by elemental analyses, IR, MS spectra, single crystal X-ray diffraction. The Ni(III) ions of 1 and 2 form a 1D zigzag non-uniform magnetic chain within a Ni(mnt)2− column through Ni⋯Ni, Ni⋯S, Ni⋯C, S⋯C, N⋯C or π⋯π interactions both at 293 and 150K (the crystal structure of 2 at 293K has been briefly reported earlier, here the crystal structure at 150K and magnetic susceptibility are investigated). Upon the temperature is lowered, the non-uniform chain has been compressed with the shortness of Ni⋯Ni distance. Variable temperature magnetic susceptibility measurements agree very well with the 1D non-uniform chain structures, and 1 exhibits a spin-gap transition around 260K with Δ/kB=1160.0K, while 2 shows two spin-gap transitions around 235.7K (Δ/kB=867.8K) and 10.4K (Δ/kB=19.1K), respectively.
•Crystal structures of three molecular metals were obtained.•The Ni(III) ions of 1 form a non-uniform 1D magnetic chain.•The Ni(III) ions of 2 form a 1D uniform chain.•The Ni(mnt)2− anions of 3 show ...a stepwise structure.•Three molecular metals exhibit an interesting characteristic of spin-gap.
Three new molecular solids, nClBzPyN(CH3)2Ni(mnt)2(BzPyN(CH3)2+=benzyl-4-dimethylaminopyridinium; mnt2−=maleonitriledithiolate; n=2(1), 3(2), 4(3)), have been prepared and characterized. The Ni(mnt)2− anions of 1 and 2 form a 1D column in which the former is non-uniform one with the Ni⋯Ni distances of 4.412 and 6.072Å, and the latter is uniform one with the distance of 7.352Å, while the ones of 3 show a stepwise structure through Ni⋯S, Ni⋯C, π⋯π, or C⋯N short interactions. The 2ClBzPyN(CH3)2+ cations(C) and Ni(mnt)2− anions (A) of 1 stack into a 1D column with a ⋯ACCACCA⋯ sequence, while the cations stake into a 1D column via N⋯π and Cl⋯Cl short interactions for 2. The change of the chlorine position on the benzyl ring from ortho, meta to para-position results in the significant differences in stacking modes of these molecular solids. Magnetic susceptibility measurements in the temperature range 2–300K show that 1, 2 and 3 exhibit a spin gap transition around 172, 150 and 92K.
Efficient adsorptive separation of propylene/propane (C3H6/C3H8) is highly desired and challenging. Known strategies focus on either the thermodynamic or the kinetic mechanism. Here, we report an ...interesting reactivity of a metal–organic framework that improves thermodynamic and kinetic adsorption selectivity simultaneously. When the metal–organic framework is heated under oxygen flow, half of the soft methylene bridges of the organic ligands are selectively oxidized to form the more polar and rigid carbonyl bridges. Mixture breakthrough experiments showed drastic increase of C3H6/C3H8 selectivity from 1.5 to 15. For comparison, the C3H6/C3H8 selectivities of the best‐performing metal–organic frameworks Co‐MOF‐74 and KAUST‐7 were experimentally determined to be 6.5 and 12, respectively. Gas adsorption isotherms/kinetics, single‐crystal X‐ray diffraction, and computational simulations revealed that the oxidation gives additional guest recognition sites, which improve thermodynamic selectivity, and reduces the framework flexibility, which generate kinetic selectivity.
Maßgeschneidert durch Sauerstoff: Wird ein flexibles Metall‐organisches Gerüst unter Sauerstoffzufluss erhitzt, werden die Hälfte der organischen Liganden selektiv oxidiert, was zu Gast‐Erkennungsstellen und einer reduzierten Flexibilität der Poren führt. Dies verbessert gleichzeitig die thermodynamische und kinetische Selektivität für die Propylen/Propan‐Trennung.
Cobalt imidazolate frameworks are classical electrocatalysts for the oxygen evolution reaction (OER) but suffer from the relatively low activity. Here, a non‐3d metal modulation strategy is presented ...for enhancing the OER activity of cobalt imidazolate frameworks. Two isomorphous frameworks Co4(MO4)(eim)6 (M=Mo or W, Heim=2‐ethylimidazole) having Co(eim)3(MO4) units and high water stabilities were designed and synthesized. In different neutral media, the Mo‐modulated framework coated on a glassy carbon electrode shows the best OER performances (1 mA cm−2 at an overpotential of 210 mV in CO2‐saturated 0.5 m KHCO3 electrolyte and 2/10/22 mA cm−2 at overpotential of 388/490/570 mV in phosphate buffer solution) among non‐precious metal catalysts and even outperforms RuO2. Spectroscopic measurements and computational simulations revealed that the non‐3d metals modulate the electronic structure of Co for optimum reactant/product adsorption and tailor the energy of rate‐determining step to a more moderate value.
Nicht‐3d für 3D: Die Einführung von nicht aus der 3d‐Reihe stammenden Metalloxid‐Bausteinen in ein Cobaltimidazolatgerüst resultiert in einer drastischen Steigerung der elektrokatalytischen Aktivität für die Sauerstoffentwicklung in neutralen Medien.
Two‐dimensional (2D) materials and ultrathin nanosheets are advantageous for elevating the catalysis performance and elucidating the catalysis mechanism of heterogeneous catalysts, but they are ...mostly restricted to inorganic or organic materials based on covalent bonds. We report an electrochemical/chemical exfoliation strategy for synthesizing metal–organic 2D materials based on coordination bonds. A catechol functionalized ligand is used as the redox active pillar to construct a pillared‐layer framework. When the 3D pillared‐layer MOF serves as an electrocatalyst for water oxidation (pH 13), the pillar ligands can be oxidized in situ and removed. The remaining ultrathin (2 nm) nanosheets of the metal–organic layers are an efficient catalyst with overpotentials as low as 211 mV at 10 mA cm−2 and a turnover frequency as high as 30 s−1 at an overpotential of 300 mV.
Extra dünn geschnitten: Ein Metall‐organisches Gerüst (MOF) mit säulenverknüpfter Schichtstruktur, liefert nach elektrochemischer Oxidation und Entfernung der Catechol‐funktionalisierten Säulen nur 2 nm dünne Nanoblätter. Diese Nanoblätter sind effiziente Elektrokatalysatoren der Wasseroxidation bei pH 13 mit niedrigem Überpotential und hoher Umsatzfrequenz (TOF).
Kushen （Radix Sophorae Flavescentis） has a long history of use for the treatment of tumors, inflammation and other diseases in traditional Chinese medicine. Compound Kushen Injection （CKI） is a ...mixture of natural compounds extracted from Kushen and Baituling （Rhizoma Smilacis Glabrae）. The main principles of CKI are matrine （MT） and oxymatrine （OMT） that exhibit a variety of pharmacological activities, including anti-inflammatory, anti-allergic, anti-viral, anti-fibrotic and cardiovascular protective effects. Recent evidence shows that these compounds also produce anti-cancer actions, such as inhibiting cancer cell proliferation, inducing cell cycle arrest, accelerating apoptosis, restraining angiogenesis, inducing cell differentiation, inhibiting cancer metastasis and invasion, reversing multidrug resistance, and preventing or reducing chemotherapy- and/or radiotherapy-induced toxicity when combined with chemotherapeutic drugs. In this review, we summarize recent progress in studying the anti-cancer activities of MT, OMT and CKI and their potential molecular targets, which provide clues and references for further study.
Molecule-inclusive closed cage compounds present a unique platform for molecular motion in an isolated environment. This study showcases the incorporation of a tadpole-like polar molecule ...(1-propyl-1H-imidazole, PIm) into a supramolecular cage formed by duad semicage p-tert-butylcalix4arene. The ferroelectric phase transition as well as the cage-confined motion of encapsulated PIm was studied in detail. The unusual quadrastable state of the PIm in the paraelectric phase allows for the modulation of dipolar polarization over a broad temperature/frequency range. This compound represents the first example of a clathrate molecular ferroelectric featuring a molecule-inclusive supramolecular cage, and it also contributes to the understanding of cage-confined molecular dynamics.Molecule-inclusive closed cage compounds present a unique platform for molecular motion in an isolated environment. This study showcases the incorporation of a tadpole-like polar molecule (1-propyl-1H-imidazole, PIm) into a supramolecular cage formed by duad semicage p-tert-butylcalix4arene. The ferroelectric phase transition as well as the cage-confined motion of encapsulated PIm was studied in detail. The unusual quadrastable state of the PIm in the paraelectric phase allows for the modulation of dipolar polarization over a broad temperature/frequency range. This compound represents the first example of a clathrate molecular ferroelectric featuring a molecule-inclusive supramolecular cage, and it also contributes to the understanding of cage-confined molecular dynamics.
A proton conductive hydrogen‐bonded organic framework (HOF) was constructed from a C3‐symmetric hexatopic carboxylic acid derivative with an 18‐crown‐6‐ether component. Despite the flexibility of the ...macrocycle, H‐bonding modules allow the derivative to yield a hexagonally networked framework with permanent porosity. As reported by Takayoshi Nakamura, Ichiro Hisaki, and co‐workers in their Communication (e202211686), the HOF possesses 1D channels with a bottleneck composed of the macrocycles and shows proton conductivity (1.12×10−7 S cm−1) through the Grotthuss mechanism (Ea=0.27 eV) under 98 %RH.
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