Chinese Journal of Chemistry最新文献

The post-synthetic modification of two-dimensional sub-stoichiometric covalent organic frameworks (COFs) for gas separation, particularly for the efficient removal of CO₂ from CO₂/N₂ mixtures, is an area of growing interest yet remains relatively unexplored. In this study, we report the precise tuning of functional groups in sub-stoichiometric COFs to enhance CO₂ capture performance. A sub-stoichiometric COF with free aldehyde groups (HPCOF) was designed and synthesized, followed by covalent modification via ethylenediamine (EDA) grafting, yielding HPCOF-EDA. This post-modification strategy significantly increased CO₂ adsorption capacity (55.7 cm³·g^–1 at 298 K and 1 bar) and CO₂/N₂ selectivity (58), primarily attributed to the formation of additional N—H···O interactions. These findings demonstrate the potential of functional engineering to broaden the application prospects of sub-stoichiometric COFs in gas adsorption and separation technologies.

Triple interlocked systems represent highly intricate topological structures, formed by entwining two mechanically interlocked cages. Achieving controlled and straightforward construction of these aesthetic topologies continues to pose an enduring challenge. Herein, we employ a coordination-driven self-assembly strategy, capitalizing on non-covalent interactions in conjunction with half-sandwich metal units and meticulously designed isoquinoline-based ligands, to achieve the effective construction of organometallic interlocked cages 1 and 2. The resulting triple interlocked system's formation and architecture were validated by single-crystal X-ray diffraction, electrospray ionization mass spectroscopy, and comprehensive NMR tests. The Independent Gradient Model (IGM) more intuitively demonstrates the multiple stacking interactions within cage compounds, while planarity analysis elucidates the self-adaptability of the ligands and their tunable conformations.

The programmability of DNA assembly allows for the creation of gold nanostructures with custom shapes and tailored optical properties, holding promise for applications including single-molecule sensing and imaging. While DNA origami provides addressable site information for structure construction, there have been few studies on encoding information onto gold nanoparticles (AuNPs) to guide the assembly of Au-DNA origami structures, especially for encoding extensive information onto large AuNPs (e.g., 30 nm). In this work, we introduce a strategy that encodes extensive information onto versatile AuNPs ranging in size from 5 nm to 30 nm using a DNA origami template (parent origami). This encoded information serves to direct the positioning of the AuNPs within a regenerated DNA origami structure (daughter origami). Our findings demonstrate the successful assembly of AuNPs ranging from 5 nm to 30 nm on the same site of the daughter DNA origami as the parent DNA origami, with yields of up to 80%. This approach offers new possibilities for achieving precise control over AuNPs assembly and functionality.

Pressure-treatment has been shown to be an effective means to enhance fluorescence of organic-inorganic halides though it is only limited to few examples. Here, we report the pressure-dependent structural evolution and emission enhancement upon compression treatment of a zero-dimensional halide, BTPP₂ZnBr₄ (BTPP = Benzyl triphenyl phosphonium). Compared to the uncompressed BTPP₂ZnBr₄ crystal, the pressure-treated sample shows a maximum 7-fold intensified fluorescence at ambient conditions while maintaining the wide-spectrum blue emission feature. This significantly boosted emission is attributed to the pressure-induced irreversible structural distortion which effectively reduces the non-radiative recombination. This work demonstrates the promising potential of pressure treatment in achieving bright organic-inorganic halide emitters and other molecular fluorescent materials.

A design strategy towards stable fluorenyl radicals (FRs) has been developed through introducing donor-π-radical (D-π-R) conjugation, facilitated by the linkage of amine N atoms and FR centers via phenyl or 9-anthryl moieties. Four FRs, with or without N atom containing protecting groups, were designed and synthesized for comparative analysis. X-ray crystallographic studies revealed the planar fluorenyl skeletons of CDP-FR and MA-FR, which exhibit significant dihedral angles relative to their protecting groups. Wiberg bond-order analysis and natural bond orbital analysis conducted on the C-C and C-N bond between the radical center and N atoms in all FRs clearly demonstrated the presence of D-π-R conjugation. Furthermore, time-dependent DFT calculations, based on frontier molecular orbital analysis, highlighted the contribution of D-π-R structures as donor-acceptor effect on the lowest energy absorptions of carbazole and diphenylamine substituted CDP-FR and DPAA-FR, which would promote charge transfer process and inhibit the photodegradation reaction. Consequently, beneficial from D-π-R conjugations, CDP-FR and DPAA-FR exhibited superior photostability compared to TP-FR and MA-FR. Our study offers a new strategy for the design and synthesis of persistent stable monoradicals.

Open-shell graphene fragments (OGFs) with non-benzenoid topologies are attracting increasing attention due to their potential applications in organic light-emitting diodes (OLEDs) and organic radical conductors. Herein, we report the synthesis of an air-stable fluorenyl radical derivative (AR1) containing a seven-membered ring, achieving thermodynamic stabilization through the fusion of a naphthalene ring around its periphery and anthracene substituent. The half-life times (τ_1/2) of AR1 in air-saturated solution is 71.9 h. The high stability was ascribed to kinetic blocking of reactive sites with high spin densities. The geometric and electronic structures of AR1 were systematically studied by combining various experimental methods and density functional theory (DFT) calculations, which include X-ray crystallographic analysis, electron spin resonance (ESR), cyclic voltammetry, and UV−vis−NIR measurements.

Imbalance in the levels of ascorbic acid (AA) can pose a risk to human health. Therefore, it's essential to establish an accurate method for the detection of AA. In this work, a novel N-doped carbon composite (MnO_x@NC) with dual enzyme-like activities to detect AA was prepared by calcination of Mn-MOF containing H₃TTPCA ligand. Interestingly, the •O₂⁻ that leads to its oxidase-like activity was not formed by dissolved oxygen, but came from the synergistic effect of lattice oxygen generated by calcination and the transformation of Mn^II/Mn^III/Mn^IV, and the presence of H₂O₂ provided much •OH, which caused its peroxidase-like activity. Meanwhile, the residual N element came from H₃TTPCA ligand assisted the catalytic process. Accordingly, a dual-signal sensing platform and smartphone-assisted recognition for detection of AA was developed and a colorimetric sensor array was established to distinguish three antioxidants. This work also demonstrates considerable promise for the detection of AA in authentic pharmaceuticals.

For coordination-insertion olefin polymerization, the development of novel transition-metal catalysts has drawn extensive attention in this field. In this contribution, we designed a series of hemilabile α-diimine nickel catalysts bearing oxygen atom as neighboring group. The steric hindrance and oxygen atom number of these nickel complexes (Ni1—Ni4) could be adjusted, which influenced ethylene (co)polymerization processes. The introduction of oxygen atoms could enhance the thermal stability during ethylene polymerization for Ni2 compared to the counterpart without oxygen atoms. And for the copolymerization process of ethylene with polar monomers, higher catalytic activity (1.4 × 10⁶ g·mol⁻¹·h⁻¹) and polar monomer incorporation ratio (1.2 mol%) were achieved. However, Ni4 with four oxygen atoms in this work was not active in ethylene polymerization due to the interaction between the oxygen atom and nickel catalytic center. The hemilabile effect in this work presented an example to enhance the stability of the α-diimine nickel catalysts in olefin polymerization.

Herein, the temperature- and pressure-stimulated responsive behavior as well as crystal-glass phase transition of a new zero-dimensional hybrid manganese bromide [4-MTPP]₂[MnBr₄] [4-MTPP⁺ = (4-methoxybenzyl)tris(phenyl)phosphonium)] were reported. Our experiment results demonstrate that [4-MTPP]₂[MnBr₄] shows typical green photoluminescence emission centered at 522.4 nm excited by UV light, with a high photoluminescence quantum yields value of 79.36% and a large lifetime of 368.6 μs, attributing to its direct bandgap electronic structure. Further, the photoluminescence emission of [4-MTPP]₂[MnBr₄] presents a monotonically blue shift with the increased temperature, originating from the decreased crystal field strength where the Mn²⁺ stays owing to lattice thermal expansion effect. On the contrary, as the pressure increases, the photoluminescence emission of [4-MTPP]₂[MnBr₄] exhibits a progressive red shift, which can be attributed to the increased crystal field strength of Mn²⁺ due to the effect of pressure-induced lattice shrinkage. Meanwhile, its quenched emission can be successfully restored when the pressure returns to the ambient pressure. In addition, [4-MTPP]₂[MnBr₄] crystals show a crystal-glass phase transition at the temperature of 74 °C. Intriguingly, the melt-quenched glass of [4-MTPP]₂[MnBr₄] exhibits green emission under UV light excitation with a large lifetime of 302.2 μs.