Chemistry - An Asian Journal最新文献

Cyclic polymers exhibit a distinctive topology that significantly differs from their linear counterparts due to their circular structure and absence of chain ends. These structural characteristics confer unique physico-mechanical properties, positioning the development of degradable and environmentally benign cyclic polyesters at the forefront of macromolecular chemistry. In this review, we examine recent advances in synthetic strategies of various cyclic polyesters and provide an overview of these cyclic polyesters’ properties. Challenges in both the synthesis and practical application of these cyclic polyesters are also discussed.

Chiral trivalent lanthanide complexes are of interest since their parity-allowed magnetic dipole transition generally shows large luminescence dissymmetry (g_lum) factors. However, the luminescence intensity is normally weak, which is yet another challenge. Herein, we introduce electron-withdrawing and -donating moieties (F and methyl, respectively) at the para-positions of phenyl on N,N'-bis (1-phenylethyl)-2,6-pyridinediamide. We found that this approach, for example, modifying the remote positions of ligands, enables decreasing the triplet state energy levels of ligands from 27060 cm⁻¹ (H) to 24154 cm⁻¹ (F) and 24390 cm⁻¹ (methyl) and enhancing the ligand-to-ion sensitization from 0.35 to 0.41 and 0.47 and photoluminescent quantum yields (PLQYs) from 17% to 23% and 25%. The g_lum-factors are ±0.1 for the three Tb(III) complexes coordinated with the synthesized ligands in their ethanol solutions, yielding circularly polarized luminescence (CPL) brightness (B) values of 0.017, 0.023, and 0.025, respectively. Single crystal structures reveal the chirality transfer from the chiral ligands to the complex and then to supramolecular chiral packing of complexes and also effective modulations on the supramolecular chiral packing. Collectively, these findings establish remote ligand engineering as a robust and versatile strategy for fine-tuning CPL brightness.

The continuous discharge of industrial dye wastewater poses severe threats to aquatic environments, urgently demanding the development of efficient and selective treatment technologies. This study designed and synthesized a zero-dimensional (0D) viologen-based metal–organic complex (VIO-MOC, formula [Cd2(μ2-Cl)Cl2Br2bpyen]) that achieves exceptional Congo Red removal performance: 99.9% removal efficiency within 30 min and a maximum adsorption capacity of 3080.6 mg/g, significantly surpassing existing flocculants. The 0D structure provides abundant exposed active sites, while electron-deficient viologen moieties interact with anionic dye molecules through π–π stacking, electrostatic interactions, and hydrogen bonding to form a potent synergistic coagulation–flocculation mechanism. Zeta potential measurements, FTIR spectroscopy, and density functional theory (DFT) calculations confirm this multi-mechanism process. VIO-MOC maintains stably high performance across pH 5–11 and remains unaffected by inorganic ion interference, demonstrating excellent practicality. This work presents a novel high-efficiency material for dye wastewater treatment and establishes key principles for designing viologen-functionalized metal–organic complexes.

The construction of C(sp²)─C(sp³) bond represents a fundamental yet challenging transformation in organic synthesis. Here, we reported a photoinduced cobalt-catalyzed reductive coupling reaction that efficiently constructs C(sp²)─C(sp³) bond between aryl bromides and 1,4-dihydropyridines. This protocol exhibits good functional group compatibility and broad substrate scope (31 examples, up to 93% yield) under mild reaction conditions. Mechanistic studies reveal that the alkylzinc reagents may be generated via photoinduced single-electron reduction, expanding the synthetic box for organozinc compound preparation.

The electrochemical reconstruction of heterostructures emerged as a striking strategy for crafting high-performance electrode materials to boost the alkaline oxygen evolution reaction (OER). This work reports the synthesis of nickel oxalate/hematite (NiOX/Fe₂O₃) heterostructure, exhibiting enhanced porosity, relocation of the electronic distribution, optimal hydrophilicity, and abundant Ni-Fe heterojunctions. Upon electrochemical reconstruction, the heterostructure transforms into Ni/Fe hydroxide-(oxy) hydroxide (named NiOX/Fe₂O₃-AP (after precondition)), demonstrating a significantly low overpotential of 234 ± 3 mV @10 mA/cm²_geo compared to individual activated counterparts. In addition, the NiOX/Fe₂O₃-AP shows swift reaction kinetics and 100 h stability across 10–100 mA/cm²_geo on redox-inactive carbon paper. The comprehensive electrochemical studies of NiOX/Fe₂O₃-AP reveal that improved active site density, higher intrinsic activity, and facile charge migration play a key role in the noted better activity. Furthermore, NiOX/Fe₂O₃-AP displayed 90 ± 4% Faradaic efficiency and improved geometric competency compared to the physical mixture, emphasizing the importance of Ni/Fe synergy. Moreover, the inferior prowess of NiFe-LDH and FeOOH compared to NiOX/Fe₂O₃-AP highlights the significance of the primitive Ni-Fe heterojunction and their subsequent electrochemical reconstruction to Ni/Fe hydroxide-(oxy) hydroxide. Finally, the electrolyzer was designed using NiOX/Fe₂O₃-AP as an anode and Pt/C as a cathode, which achieved 1.518 ± 0.006 V cell potential at 10 mA/cm²_geo, sustaining 80 h across 10–100 mA/cm²_geo.

Design of stimuli-responsive chiral polydiacetylenes (PDAs) with an innate photoswitch offers exciting opportunities toward tunable chromogenesis and chiroptical behavior as a result of E-Z photoisomerization. We designed a series of asymmetric photopolymerizable diacetylene bisamides bearing variable alkyl chains, DA_n (n = 2, 5, 10), to connect the DA with a chiral azobenzene motif. Topochemical polymerization in thin films of DA forms orange colored PDAs to furnish long-ranged fibrillar nanostructures with increasing alkyl chain lengths. The polymer nanostructures exhibit axial or lateral growth after thermal annealing due to improved ordering in the polymeric domains. The PDA self-assembly exhibits crystalline or soft-crystalline packing based on alkyl chain stacking, aromatic interactions, and hydrogen bonding. Differential molecular packing in the PDAs dictates the E to Z photoisomerization percentages, eventually resulting in diminishing chiroptical signatures and anisotropic textures. Photoisomerization-mediated dynamic disassembly in 1D nanofibers are observed in the PDAs bearing decyl chain spacers, which show prominent room temperature soft-crystalline switching behavior. Reverse photoisomerization of Z to E mediated structural reordering result recovery of the chiral packing, morphology, and birefringent patterns. Such tunable soft-crystalline PDAs provide a convenient access to soft adaptable chiroptical materials toward solid-state actuation applications.

Electrocatalytic water electrolysis is intrinsically limited by the slow kinetics of the oxygen evolution reaction (OER) at the anodic electrode. The development of highly active and stable catalysts for the OER is both essential and challenging. In this work, we employed porous metal-organic frameworks (MOFs) to synthesize Ru-etched MOF-derived CuCoO₂ nanocrystals used as an OER catalyst. The electrochemical test results revealed that the Ru-etched CuCoO₂ electrode (Ni@CCORu-3) synthesized via a 3 h RuCl₃-etching reaction exhibits superior catalytic activity (η₁₀ = 368.4 mV, Tafel slope = 81.2 mV dec⁻¹) in 1.0 M KOH electrolyte. After an 18 h OER stability test, the Ni@CCORu-3 exhibited excellent stability with a minimal overpotential degradation of approximately 30 mV. This enhancement in OER activity can be attributed to the improved specific surface area and pore structure of the MOF-derived CCORu-3 catalyst, resulting from RuCl₃ etching. Furthermore, the electron distribution on the catalyst surface is modulated by Ru species loaded onto the surface. X-Ray photoelectron spectroscopy (XPS) and ultraviolet-visible-near infrared (UV-Vis-NIR) absorption spectra results revealed that RuCl₃ etching increases the proportion of active sites and narrows the bandgap of CuCoO₂, thereby accelerating electron transfer rates during the OER process and optimizing catalytic activity. This study may provide a novel insight into enhancing the OER performance of CuCoO₂ catalysts derived from MOFs.

Metal–organic frameworks (MOFs) are promising electrocatalysts for the oxygen evolution reaction (OER), owing to their high surface areas, tailorable structures, and numerous potential active sites. Herein, we investigate the impact of flow velocity within microchannels on the crystallization rate and internal structures of Co-MOF-74 via an air–liquid segmented flow method. We demonstrate that a higher flow velocity enhances the frequency of collisions between the metal ions and the organic linkers, yielding Co-MOF-74 samples with improved crystallinity, and unique voids. Specifically, the A-Co-MOF-74-8v synthesized at high flow velocity, exhibits a smaller particle size, developed internal voids, and abundant accessible electroactive sites. These features facilitate efficient mass transport and gas release during electrolysis, leading to significantly enhanced electrocatalytic OER performance. In 1 M KOH, A-Co-MOF-74-8v achieves a low overpotential of 310 mV at 10 mA cm⁻², which is 42 mV lower than that of the solvothermally synthesized counterpart (ST-Co-MOF-74). This work provides key mechanistic insights and design principles for engineering highly efficient MOF-based electrocatalysts under precisely controlled microfluidic conditions.