Circularly polarized luminescence (CPL) reflects the excited-state properties of the chiral system. However, compared to the singlet and triplet excited states, there are still many unknowns about ...CPL from the double excited state. Here, using the self-assembly strategy of a dipeptide substituted naphthalenediimide (NDI-GE) and the photogenerated radical anions, we have explored the ground-state (CD) and excited-state (CPL) chiral characteristics of neutral NDI and NDI•– radical anion assemblies. The neutral gelator assemblies showed CPL with the dissymmetry factor g lum on the order of 10–3; the radical anion exhibited an inversed CPL signal with a significantly enhanced g lum of 10–1. Time-dependent density functional theory calculation revealed that upon formation of the radical anions, the direction of the dipole moment changed, thus leading to the inversion of CD and CPL. The present work reveals a new platform for developing CPL materials based on the doublet excited state.
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Twisted ribbons were formed by the self‐assembly of racemic alanine derivatives (middle picture), whereas only flat nanostructures were obtained from the individual enantiomers (left). The twist was ...sensitive to a slight enantiomeric excess and showed remarkable macroscopic chirality. Moreover, it could discriminate various amino acid derivatives (right) and even enabled the determination of the ee value of a mixed system.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
High quality graphene sheets were prepared from graphite powder through oxidation followed by rapid thermal expansion in nitrogen atmosphere. The preparation process was systematically investigated ...by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and Brunauer–Emmett–Teller (BET) measurements. The morphology and structure of graphene sheets were characterized by scanning electron microscope (SEM) and high-resolution transmission electron microscopy (HRTEM). The electrochemical performances were evaluated in coin-type cells versus metallic lithium. It is found that the graphene sheets possess a curled morphology consisting of a thin wrinkled paper-like structure, fewer layers (∼4 layers) and large specific surface area (492.5
m
2
g
−1). The first reversible specific capacity of the prepared graphene sheets was as high as 1264
mA
h
g
−1 at a current density of 100
mA
g
−1. Even at a high current density of 500
mA
g
−1, the reversible specific capacity remained at 718
mA
h
g
−1. After 40 cycles, the reversible capacity was still kept at 848
mA
h
g
−1 at the current density of 100
mA
g
−1. These results indicate that the prepared high quality graphene sheets possess excellent electrochemical performances for lithium storage.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Biomimetic ATP‐driven supramolecular assembly is important to understand various biological processes and dissipative systems. Here, we report an ATP‐driven chiral assembly exhibiting circularly ...polarized luminescence (CPL) via the interaction of an achiral terpyridine‐based ZnII complex with nucleotides. It was found that while the metal complexes could co‐assemble with the nucleotides to form fluorescent assemblies, only a combination of furan‐substituted terpyridine complex and ATP showed an intense CPL with a dissymmetry factor (glum) as high as 0.20. This means that the complex could recognize ATP using CPL as a readout signal, thus providing an example of ATP encryption. Interestingly, when ATP was transferred into ADP or AMP under enzymatic hydrolysis, the CPL decreases or disappears. Addition of ATP generates CPL again, thus producing an ATP‐induced CPL system. This work presents the first example of ATP‐induced CPL and encryption.
An achiral terpyridine‐based ZnII complex has been developed that forms fluorescent complexes with nucleotides, but only in the presence of ATP. A chiral assembly is generated that exhibits circularly polarized luminescence (CPL) with a glum factor as high as 0.20. This discrimination of ATP from other nucleotides should allow applications in encryption.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The effort on electrochemical reduction of CO2 to useful chemicals using the renewable energy to drive the process is growing fast recently. In this review, we introduce the recent progresses on the ...electrochemical reduction of CO2 in solid oxide electrolysis cells（SOECs）. At high temperature, only CO is produced with high current densities and Faradic efficiency while the reactor is complicated and a better sealing technique is urgently needed. The typical electrolytes such as zirconia-based oxides, ceria-based oxides and lanthanum gallates-based oxides, anodes and cathodes are introduced in this review, and the cathode materials, such as conventional metal–ceramics（cermets）, mixed ionic and electronic conductors（MIECs） are discussed in detail. In the future, to gain more value-added products, the electrolyte, cathode and anode materials should be developed to allow SOECs to be operated at temperature range of 573–873 K. At those temperatures, SOECs may combine the advantages of the low temperature system and the high temperature system to produce various products with high current densities.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Directing acoustic waves along curved paths is critical for applications such as ultrasound imaging, surgery and acoustic cloaking. Metamaterials can direct waves by spatially varying the material ...properties through which the wave propagates. However, this approach is not always feasible, particularly for acoustic applications. Here we demonstrate the generation of acoustic bottle beams in homogeneous space without using metamaterials. Instead, the sound energy flows through a three-dimensional curved shell in air leaving a close-to-zero pressure region in the middle, exhibiting the capability of circumventing obstacles. By designing the initial phase, we develop a general recipe for creating self-bending wave packets, which can set acoustic beams propagating along arbitrary prescribed convex trajectories. The measured acoustic pulling force experienced by a rigid ball placed inside such a beam confirms the pressure field of the bottle. The demonstrated acoustic bottle and self-bending beams have potential applications in medical ultrasound imaging, therapeutic ultrasound, as well as acoustic levitations and isolations.
Abstract
Biodiversity is crucial for the provision of ecosystem functions. However, ecosystems are now exposed to a rapidly growing number of anthropogenic pressures, and it remains unknown whether ...biodiversity can still promote ecosystem functions under multifaceted pressures. Here we investigated the effects of soil microbial diversity on soil functions and properties when faced with an increasing number of simultaneous global change factors in experimental microcosms. Higher soil microbial diversity had a positive effect on soil functions and properties when no or few (i.e., 1–4) global change factors were applied, but this positive effect was eliminated by the co-occurrence of numerous global change factors. This was attributable to the reduction of soil fungal abundance and the relative abundance of an ecological cluster of coexisting soil bacterial and fungal taxa. Our study indicates that reducing the number of anthropogenic pressures should be a goal in ecosystem management, in addition to biodiversity conservation.
Two enantiomeric hydrohelicenes containing a hydroxyl group and a π-conjugated nonplanar structure are assembled at the air/water interface. These molecules are found to form spreading films with ...well-defined surface pressure–area isotherms. Upon transferring the spreading film onto the mica surface, porous nanostructures are observed. The spreading film can be transferred onto solid substrates by the Langmuir–Schaefer (LS) method and the transferred LS films display optical activity as revealed by the circular dichroism (CD) spectra. The P- and M-hydrohelicene enantiomers showed mirrored CD spectra, suggesting that the chirality of the LS films was controlled by molecular chirality. When these molecules are spread on the aqueous solution containing metal ions such as Ag+, Cu2+, and Zn2+, a clear twisted ring nanostructure, which is similar to the Möbius strip, is observed. It is suggested that the interaction between the hydroxyl groups of helicenes and metal ions induced such a ring nanostructure.
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