Chemistry - An Asian Journal最新文献

Compared to the traditional graphite anode, heteroatom-doped polymer carbon materials have high capacity retention due to their high porosity and porous structure. Therefore, they have great potential for application in lithium-ion battery (LIB) anodes. In this work, an N, P co-doped precursor polymer material (MBPp), synthesized via a one-pot method using bisphenol-A (C-source), melamine (N-source), and 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (P-source). The resulting N, P-co-doped hard carbon materials (MBPs) were prepared at various pyrolysis temperatures, yielding microporous, mesoporous, and macroporous structures. MBP materials demonstrated excellent electrochemical performance as LIB anodes. Notably, MBP-900 achieved a reversible capacity of 262 mAh g-1 at 1000 mA g-1 (in 0.005-2.0 V voltage range) with a capacity retention rate of 97.2% after 1000 cycles. These findings highlight the significance of MBP materials, which possess numerous defects, large layer gaps, and excellent cycle stability, in advancing the development of polymer anode materials for LIBs.

Carbon dots (CDs) are carbon-based nanomaterials that have garnered immense interest due to their exceptional photophysical and optoelectronic properties. They have been employed extensively for biomedical imaging and phototherapy due to their superb water dispersibility, low toxicity, outstanding biocompatibility, and exceptional tissue permeability. This review summarizes the luminescence mechanism of CDs. The modification in CDs via various doping routes is comprehensively reviewed, and the effect of such alterations on their photophysical properties, such as photoluminescence (PL), absorbance, and reactive oxygen species generation ability, is also highlighted. This review also aims to summarize the role of CDs in cellular imaging and fluorescence lifetime imaging for cellular metabolism. Subsequently, recent advancements and the future prospects of CDs as nanotheranostic agents have been discussed. Herein, we have discussed the role of CDs in photothermal, photodynamic, and synergistic therapy of anticancer, antiviral, and antibacterial applications. The overall summary of the review highlights the future prospects of CD-based research in bioimaging and biomedicine.

In article number e202400744 by Prakash Chandra Mondal and co-workers, the electrochemical charge transfer of a ferrocene/ferrocenium redox couple is investigated using different commercial and fabricated working electrodes of technical relevance. The kinetics of electron transfer and electrochemical reversibility reveal a strong dependence on the nature of the working electrode surface.

Chiral luminescent liquid crystal (LC) materials with switchable circularly polarized luminescence (CPL) signals have received extensive attention, in which the use of light stimulation to achieve different CPL states is of great significance. However, there are very few reports on the generation and regulation of CPL signals enabled by blue phase LC (BPLC). Herein, achieving CPL signal inversion based on the phase transition induced by light/temperature stimulation in a BPLC system with a wide room-temperature window is reported. A binaphthalene azo-based chiral photoswitch (S)-switch 3 with high helical twisted power (HTP) and large HTP variation is synthesized, and a BP system with a wide room temperature range is further fabricated by doping (S)-switch 3 and a fluorescence molecule into a bulk LC. By regulating the doping amount of (S)-switch 3, a phase transition from BP to cholesteric (Ch) phase at room temperature is observed upon 365 nm UV light irradiation or during cooling process, and the polarization inversion of CPL signal is correspondingly found due to the different CPL generation mechanisms of BPLC and CLC. This study provides a new strategy for the flexible regulation of CPL signals in a BPLC system.

The utilization of solar-driven technologies for the direct conversion of methanol (CH3OH) into two or multi-carbon compounds through controlled carbon-carbon (C-C) coupling is an appealing yet challenging objective. In this study, we successfully demonstrate the photocatalytic CH3OH coupling to ethylene (C2H4), a valuable chemical raw material, by employing a carbon nitride-based catalyst. Specifically, we modify the layered polymer carbon nitride (PCN) photocatalyst through the incorporation of Au single atoms (Au1/PCN) using a chemical-scissors method. The synergistic effect between the PCN substrate and the Au single atoms reduces the potential barrier associated with C-C coupling, thereby enhancing the efficiency of CH3OH reforming to C2H4. This investigation not only reveals a novel pathway for C2H4 production via CH3OH reforming but also provides fresh insights into the possibilities of C-C coupling.

Classically, aromaticity portrays the unique stability and peculiar reactivities of cyclic planar conjugated systems with (4n+2) π electrons. Understanding the electronic environments in new chemical frameworks through experimental and theoretical validation is central to this ever-expanding theme in chemical science. Such investigations in curved π-surfaces have special significance as they can unravel the variations when the planarity requirement is slightly lifted. In this report, we discuss the synthesis, spectroscopic and theoretical studies involving a new group of cyclazine analogs having a charged aza[10]annulene periphery, centrally locked through a sp3 carbon. Magnetic anisotropic effects arising from electron delocalization through its curved π-surface were mapped through a specific set of chemical groups introduced through this sp3 carbon. The nucleus-independent chemical shift calculations revealed negative chemical shift values, indicating the aromatic nature of the aza[10] annulene rim. This is corroborated by a clockwise diatropic ring current, evident from anisotropy-induced current density analysis. Variations in the chemical shift of NMR signals in these systems were also computationally examined through isotropic chemical shielding surface analysis.

The activation of Cu-zeolite catalysts is accompanied by an autoreduction reaction, in which a part of Cu(II) species is spontaneously reduced to Cu(I) species. The stoichiometry of autoreduction in which the release of one O₂ is accompanied by the reduction of four Cu(II) to Cu(I) has been proposed, but the detailed mechanism of this autoreduction remains unclear. In this work, we used DFT calculations to study the autoreduction mechanism in Cu-CHA zeolites. The two reduction mechanisms of [CuOH]⁺ to Cu⁺ in CHA-type zeolite were systematically studied. In Mechanism I, two [CuOH]⁺ react via dehydration to form [Cu-O-Cu]²⁺, and the further reaction of two [Cu-O-Cu]²⁺ to produce O₂ is the most critical step, which requires four charge-compensating framework Al in close proximity. In Mechanism II, the production of O₂ occurs via [CuO]⁺ intermediates, and the generation of possible [CuO]⁺ is the most critical step. The exploration of autoreduction reactions in a variety of Cu-CHA models with different Al sittings shows that the O-O distances between two intermediate precursors, i. e., two [Cu-O-Cu]²⁺ in Mechanism I, or two [CuO]⁺ in Mechanism II, are key factors determining the activation barriers of O₂ production during autoreduction.

We have developed a visible-light-mediated convenient and efficient strategy for the iodination of heteroarenes using diacetoxyiodobenzene (PIDA) under photocatalyst-free conditions. This unique approach is the first report on photocatalytic C-H iodination employing PIDA as the iodinating agent. The new photocatalyst-free strategy is applicable to a wide range of pyrazolo[1,5-a]pyrimidine derivatives with various functionalities. Iodination of other electron-rich heterocycles like imidazo[1,2-a]pyridine, imidazo[1,2-a]pyrimidine, imidazo[2,1-b]thiazole, benzo[d]imidazo[2,1-b]thiazole, and pyrazoles has been accomplished employing this benign protocol. The usefulness of 3-iodo pyrazolo[1,5-a]pyrimidine as a synthetic intermediate in synthesizing various functionalized pyrazolo[1,5-a]pyrimidines has been demonstrated.

We have successfully improved the fluorescence quantum yield of isoindolo[2,1-a]quinoline derivatives by suppressing the rotation of the phenyl groups at positions 5 and 11 (or 13). Additionally, we found that the planarity of these phenyl groups at positions 5 and 13 of isoindolo[2,1-a]quinoline derivatives is crucial for two-photon absorption properties.

Herein, the Cu-UiO-66 catalyst was developed for acceptorless dehydrogenative coupling (ADC) between alcohols and amines to produce imines. The Cu-UiO-66 catalyst was synthesized by installing Cu²⁺ onto Zr-oxo clusters in UiO-66, and the catalyst efficiently catalyzes the ADC reaction under mild and environmentally friendly conditions with excellent selectivity. Mechanistic studies reveal that the O₂⋅^- radicals and porosity of formed in Cu-UiO-66 participate cooperatively during the catalytic cycle. Meanwhile, the only by-product of the system is environmentally benign water. Cycling tests and hot filtration tests showed that the Cu-UiO-66 catalyst exhibited excellent stability and catalytic activity during the reaction. Importantly, the Cu-UiO-66 catalyst might provide a promising strategy for the ADC reaction between alcohols and amines to produce imines.