Heterogeneous catalysts typically lack the specific steric control and rational electronic tuning required for precise asymmetric catalysis. Here we demonstrate that a phosphonate metal-organic ...framework (MOF) platform that is robust enough to accommodate up to 16 different metal clusters, allowing for systematic tuning of Lewis acidity, catalytic activity and enantioselectivity. A total of 16 chiral porous MOFs, with the framework formula M
L
(solvent)
that have the same channel structures but different surface-isolated Lewis acid metal sites, are prepared from a single phosphono-carboxylate ligand of 1,1'-biphenol and 16 different metal ions. The phosphonate MOFs possessing tert-butyl-coated channels exhibited high thermal stability and good tolerances to boiling water, weak acid and base. The MOFs provide a versatile family of heterogeneous catalysts for asymmetric allylboration, propargylation, Friedel-Crafts alkylation and sulfoxidation with good to high enantioselectivity. In contrast, the homogeneous catalyst systems cannot catalyze the test reactions enantioselectively.
Nonhalogenated polymers have great potential in the commercialization of organic photovoltaic (OPV) cells due to their advantage in low‐cost preparation. However, non‐halogenated polymers usually ...have high highest occupied molecular orbital (HOMO) energy levels and inferior self‐aggregation properties in solution, thus resulting in low power conversion efficiencies (PCEs). Herein, two nonhalogenated polymers, PB1 and PB2, are prepared. When the polymers are used to fabricate OPV cells with BTP‐eC9, the PB1‐based device only gives a PCE of 5.3%, while the PB2‐based device shows an outstanding PCE of 17.7%. After the introduction of PBDB‐TF as the third component, the PB2:PBDB‐TF:BTP‐eC9‐based device with an optimal weight ratio of 0.5:0.5:1 achieves a PCE up to 18.4%. More importantly, PB2 exhibits good compatibility with various nonfullerene acceptors to achieve better PCEs than those of classical polymer (PBDB‐T and PBDB‐TF)‐based devices. When PB2 is combined with a wide‐bandgap electron acceptor (F‐BTA3), this device shows excellent PCE of 27.1% and 24.6% for 1 and 10 cm2 devices, respectively, under light intensity of 1000 lux light‐emitting diode illumination. These results provide new insight in the rational design of novel nonhalogenated polymer donors for further development of low‐cost materials and broadening the application of OPV cells.
Two nonhalogenated polymers, PB1 and PB2, with different side‐chain orientations and deep highest occupied molecular orbital (HOMO) levels are reported. In organic photovoltaic (OPV) cells, PB1 only produces a power conversion efficiency (PCE) of 5.3%, while PB2 gives an outstanding PCE of 17.7%. More importantly, PB2 has good compatibility with various electron acceptors. PB2 achieves excellent PCEs of 18.4% and 27.1% for ternary OPV cells and indoor light photovoltaic devices, respectively.
A highly fluorescent coordination cage Zn8L4I8 has been constructed by treating enantiopure pyridyl‐functionalized metallosalalen units (L) with zinc(II) iodide and characterized by a variety of ...techniques including microanalysis, thermogravimetric analysis (TGA), circular dichroism (CD) spectroscopy, and single‐crystal and powder X‐ray diffraction. Strong intermolecular π–π, CH⋅⋅⋅π, and CH⋅⋅⋅I interactions direct packing of the cage molecules to generate a 3D polycage network interconnected by pentahedral cages formed by adjacent pentamers. The cage has an amphiphilic helical cavity decorated with chiral NH functionalities capable of interactions with guest species such as saccharides. The fluorescence of the cage was greatly enhanced by five enantiomeric saccharides in solution, with enantioselectivity factors of 2.480–4.943, and by five enantiomeric amines in the solid state, with enantioselective fluorescence enhancement ratios of 1.30–3.60. This remarkable chiral sensing of both saccharides and amines with impressive enantioselectivity may result from the steric confinement of the cavity as well as its conformational rigidity. It holds great promise for the development of novel chiral cage materials for sensing applications.
Cage‐based chiral sensor: A highly fluorescent coordination cage Zn8L4I8 can be prepared from enantiopure pyridyl‐functionalized metallosalalen units (L). The cage has an amphiphilic helical cavity decorated with chiral NH functionalities and supramolecular interactions generate a 3D polycage network interconnected by pentahedral cages formed by adjacent pentamers (see graphic). The fluorescence of the cage is greatly enhanced either in solution or in the solid state in the presence of enantiomeric saccharides or amines, respectively, with significant enantioselectivity factors.
Nanosupramolecular assemblies with controlled topological features have inventive applications in fundamental studies and material manufacturing. Herein, a variety of morphologically interesting ...aggregates have been constructed using the supramolecular modulation with bipyridinium‐modified diphenylalanine derivative (BP‐FF). Benefiting from the high binding affinity of bipyridinium group with four different macrocyclic receptors, namely cucurbit7uril, cucurbit8uril, pillar5arene, and tetrasulfonated crown ether, we have succeeded in tuning the topological aggregates of BP‐FF from fine nanofibers to nanorods, octahedron‐like nanostructure, helical nanowires, and rectangular nanosheets without any tedious chemical modification. This supramolecular approach may provide us a powerful method to construct well‐defined nanostructures with different morphologies that can be conveniently controlled by facile host–guest interactions.
Be my guest: A variety of morphologically interesting aggregates have been constructed. The method uses supramolecular modulation of a bipyridinium‐modified diphenylalanine guest with four different macrocyclic hosts. Azoim=azophenyl imidazolium salt.
Apoptosis plays a key role in keloids. Growth arrest and DNA damage‐inducible gene 153 (GADD153) is regulated by apoptosis. Botulinum toxin type A (BTXA) can induce apoptosis in keloid fibroblasts. ...This research aimed to explore the hypothesis that GADD153 mediates apoptosis in keloid fibroblasts exposed to BTXA. BTXA significantly induced GADD153 protein and mRNA expression in keloid fibroblasts. Treatment with c‐Jun N‐terminal kinase (JNK) inhibitor SP600125, JNK small interfering RNA (siRNA) and tumour necrosis factor‐alpha (TNF‐α) antibodies reversed the BTXA‐induced GADD153 expression. BTXA enhanced the transcriptional activity of GADD153, whereas the GADD153 mutant plasmid, JNK siRNA and anti‐TNF‐α antibody treatment abolished the BTXA‐induced transcriptional activity of GADD153. The addition of TNF‐α to keloid fibroblasts markedly increased GADD153 protein expression. The addition of GADD153 siRNA, SP600125 and anti‐TNF‐α antibodies reversed cell death and caspase 3 and 9 activity induced by BTXA.
Reducing non-radiative charge recombination is of critical importance to achieving high-performance organic photovoltaic (OPV) cells. The correlation between the exciton behaviors and non-radiative ...charge recombination is rarely studied. In this work, we achieved an increase in the exciton diffusion length (LD) in the acceptor phase via introducing HDO-4Cl to the PBDB-TF:eC9-based system. Compared with the eC9-based film, the exciton LD in the HDO-4Cl:eC9-based film is increased from 12.2 to 16.3 nm. The enlarged exciton LD can obviously decrease the non-radiative charge recombination and increase the efficiency of photon utilization in the PBDB-TF:eC9-based OPV cell. Finally, we not only obtained an outstanding power conversion efficiency (PCE) of 18.86% but also demonstrated the correlations between the non-radiative energy loss and exciton behaviors. The results show that regulating the exciton behaviors is an effective way to reduce the non-radiative energy loss and realize high-efficiency OPV cells.
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•Correlations between non-radiative energy loss and exciton behaviors are revealed•The exciton-diffusion length can be effectively enlarged through ternary strategy•A high PCE approaching 19% is demonstrated
Organic photovoltaic (OPV) cells have recently emerged as cost-effective and energy-efficient candidates of green energy sources. Further improvement in power conversion efficiency (PCE) is still needed for practical application. Compared with the inorganic photovoltaic cells, the non-radiative energy loss (Eloss, non-rad) in OPV cell is relatively large. Therefore, reducing the Eloss, non-rad is an effective way to achieve a breakthrough in the PCE of OPV cells. In addition to material synthesis and morphology optimization, optimizing exciton behaviors is also crucial to reduce the Eloss, non-rad and, thus, enhance the state-of-art high-performance OPV cells. In this work, the exciton diffusion length in PBDB-TF:eC9-based active layer is effectively enhanced through introducing a third component named HDO-4Cl. As a result, we not only achieved an outstanding PCE of approaching 19% but also revealed the correlations between the Eloss, non-rad and exciton behaviors.
Suppressing the non-radiative energy loss by optimizing the exciton behaviors in PBDB-TF:eC9-based organic photovoltaic (OPV) cells is demonstrated in this work. The exciton diffusion length and exciton lifetime in the active layer based on PBDB-TF:eC9 are enhanced via introducing HDO-4Cl, resulting in the obvious reduction in the non-radiative charge recombination in the corresponding OPV cell. As a result, a high PCE of 18.86% is achieved in the single-junction OPV cell.
Cage rage: Chiral tetrahedral cages are diastereoselectively self‐assembled from enantiopure C2‐symmetric biphenyl bis(β‐diketonate) linkers and C3‐symmetric octahedral Fe3+ or Ga3+ ions (see ...picture; Fe purple, C blue, O red; cavity shown as an orange sphere). The porous polyhedra exhibit metal‐dependent chiroptical behavior and act as hosts for the crystallization separation of racemic alcohols with up to 99.5 % ee.
Abstract
Moiré coupling in transition metal dichalcogenides (TMDCs) superlattices introduces flat minibands that enable strong electronic correlation and fascinating correlated states, and it also ...modifies the strong Coulomb-interaction-driven excitons and gives rise to moiré excitons. Here, we introduce the layer degree of freedom to the WSe
2
/WS
2
moiré superlattice by changing WSe
2
from monolayer to bilayer and trilayer. We observe systematic changes of optical spectra of the moiré excitons, which directly confirm the highly interfacial nature of moiré coupling at the WSe
2
/WS
2
interface. In addition, the energy resonances of moiré excitons are strongly modified, with their separation significantly increased in multilayer WSe
2
/monolayer WS
2
moiré superlattice. The additional WSe
2
layers also modulate the strong electronic correlation strength, evidenced by the reduced Mott transition temperature with added WSe
2
layer(s). The layer dependence of both moiré excitons and correlated electronic states can be well described by our theoretical model. Our study presents a new method to tune the strong electronic correlation and moiré exciton bands in the TMDCs moiré superlattices, ushering in an exciting platform to engineer quantum phenomena stemming from strong correlation and Coulomb interaction.
This review introduces the basic material science concepts and principles behind some common topics in the development of pharmaceutical solid formulations. The physiochemical properties of small ...organic pharmaceutical materials are summarized. Common phases, differences in phases, phase transitions, and their relation to pharmaceutical development are reviewed. The characteristics and physical nature of solid phases, including crystalline and amorphous solids, are presented in conjunction with some pharmaceutically relevant phenomena, such as polymorphism, phase transition kinetics, and relaxation. Mesophases, including liquid crystals and condis crystals, are introduced. The potential energy states of different phases are highlighted as the key connection between the physical nature of the materials and their pharmaceutical behavior, and energy landscape is employed to enhance the understanding of this relation.
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