Precision Chemistry最新文献

While photocatalytic CO₂ reduction has been intensively investigated, reports on the influence of anions coordinated to catalytic metal sites on CO₂ photoreduction remain limited. Herein, different coordinated anions (F^–, Cl^–, OAc^–, and NO₃^–) around single Co sites installed on bipyridine-based three-component covalent organic frameworks (COFs) were synthesized, affording TBD-COF-Co-X (X = F, Cl, OAc, and NO₃), for photocatalytic CO₂ reduction. Notably, the presence of these coordinated anions on the Co sites significantly influences the photocatalytic performance, where TBD-COF-Co-F exhibits superior activity to its counterparts. Combined experimental and theoretical results indicate that the enhanced activity in TBD-COF-Co-F is attributed to its efficient charge transfer, high CO₂ adsorption capacity, and low energy barrier for CO₂ activation. This study provides a new strategy for boosting COF photocatalysis through coordinated anion regulation around catalytic metal sites.

While photocatalytic CO₂ reduction has been intensively investigated, reports on the influence of anions coordinated to catalytic metal sites on CO₂ photoreduction remain limited. Herein, different coordinated anions (F^-, Cl^-, OAc^-, and NO₃ ^-) around single Co sites installed on bipyridine-based three-component covalent organic frameworks (COFs) were synthesized, affording TBD-COF-Co-X (X = F, Cl, OAc, and NO₃), for photocatalytic CO₂ reduction. Notably, the presence of these coordinated anions on the Co sites significantly influences the photocatalytic performance, where TBD-COF-Co-F exhibits superior activity to its counterparts. Combined experimental and theoretical results indicate that the enhanced activity in TBD-COF-Co-F is attributed to its efficient charge transfer, high CO₂ adsorption capacity, and low energy barrier for CO₂ activation. This study provides a new strategy for boosting COF photocatalysis through coordinated anion regulation around catalytic metal sites.

Using density functional theory, we carefully calculated the relative stability of monolayer, few-layer, and cluster structures with Penta PdSe₂, T-phase PdSe₂, and Pd₂Se₃-phase. We found that the stability of Penta PdSe₂ increases with the number of layers. The Penta PdSe₂, T-phase PdSe₂, and Pd₂Se₃ monolayers are all semiconducting, with band gaps of 1.77, 0.81, and 0.65 eV, respectively. The formation energy of palladium selenide clusters with different phase structures is calculated, considering the cluster size, stoichiometry, and chemical environment. Under typical experimental conditions, Pd₂Se₃ phase clusters are found to be dominant, having the lowest formation energy among all of the phases considered, with this dominance increasing as cluster size grows. Adjusting the Pd-Se ratio in the environment allows for controlled synthesis of specific palladium selenide phases, providing theoretical insights into the nucleation mechanisms of PdSe₂ and other transition metal chalcogenides.

Using density functional theory, we carefully calculated the relative stability of monolayer, few-layer, and cluster structures with Penta PdSe₂, T-phase PdSe₂, and Pd₂Se₃-phase. We found that the stability of Penta PdSe₂ increases with the number of layers. The Penta PdSe₂, T-phase PdSe₂, and Pd₂Se₃ monolayers are all semiconducting, with band gaps of 1.77, 0.81, and 0.65 eV, respectively. The formation energy of palladium selenide clusters with different phase structures is calculated, considering the cluster size, stoichiometry, and chemical environment. Under typical experimental conditions, Pd₂Se₃ phase clusters are found to be dominant, having the lowest formation energy among all of the phases considered, with this dominance increasing as cluster size grows. Adjusting the Pd–Se ratio in the environment allows for controlled synthesis of specific palladium selenide phases, providing theoretical insights into the nucleation mechanisms of PdSe₂ and other transition metal chalcogenides.

The integration of multiple chromophore units into a single molecule is expected to improve the performance of photon upconversion based on triplet-triplet annihilation (TTA-UC) that can convert low energy photons to higher energy photons at low excitation intensity. In this study, a macrocyclic parallel dimer of 9,10-diphenylanthracene (DPA) with a precisely parallel orientation, named MPD-2, is synthesized, and its TTA-UC properties are investigated. MPD-2 shows a green-to-blue TTA-UC emission in the presence of a triplet sensitizer, platinum octaethylporphyrin (PtOEP). Compared to monomeric DPA, MPD-2 results in an enhancement of the spin statistical factor of TTA and a decrease in the excitation light intensity due to the intramolecular TTA process. The obtained structure-property relationship provides important information for the further improvement of TTA-UC properties.

The integration of multiple chromophore units into a single molecule is expected to improve the performance of photon upconversion based on triplet–triplet annihilation (TTA-UC) that can convert low energy photons to higher energy photons at low excitation intensity. In this study, a macrocyclic parallel dimer of 9,10-diphenylanthracene (DPA) with a precisely parallel orientation, named MPD-2, is synthesized, and its TTA-UC properties are investigated. MPD-2 shows a green-to-blue TTA-UC emission in the presence of a triplet sensitizer, platinum octaethylporphyrin (PtOEP). Compared to monomeric DPA, MPD-2 results in an enhancement of the spin statistical factor of TTA and a decrease in the excitation light intensity due to the intramolecular TTA process. The obtained structure–property relationship provides important information for the further improvement of TTA-UC properties.

Single-molecule bioelectronic sensing, a groundbreaking domain in biological research, has revolutionized our understanding of molecules by revealing deep insights into fundamental biological processes. The advent of emergent technologies, such as nanogapped electrodes and nanopores, has greatly enhanced this field, providing exceptional sensitivity, resolution, and integration capabilities. However, challenges persist, such as complex data sets with high noise levels and stochastic molecular dynamics. Artificial intelligence (AI) has stepped in to address these issues with its powerful data processing capabilities. AI algorithms effectively extract meaningful features, detect subtle changes, improve signal-to-noise ratios, and uncover hidden patterns in massive data. This review explores the synergy between AI and single-molecule bioelectronic sensing, focusing on how AI enhances signal processing and data analysis to boost accuracy and reliability. We also discuss current limitations and future directions for integrating AI, highlighting its potential to advance biological research and technological innovation.

Recently, the chain-walking ethylene polymerization strategy has garnered widespread attention as an efficient and straightforward method for preparing polyolefin elastomers. In this study, a series of 2,4,8-triarylnaphthyl iminopyridyl nickel catalysts were synthesized and used in ethylene polymerization. These catalysts demonstrated moderate catalytic activity (10⁵ g mol^-1 h^-1), producing high-molecular-weight (up to 145.5 kg/mol) polyethylene materials with high branching degrees (75-95/1000C) and correspondingly low melting points. Detailed analysis using ¹³C NMR spectroscopy revealed that the polyethylenes primarily featured methyl and long-chain branches. Mechanical testing of the polyethylene samples obtained from catalysts Ni1-Ni3 exhibited moderate stress at break (4.64-6.97 MPa) coupled with a very high strain at break (1650-3752%), indicating their very good ductility. Furthermore, these polyethylenes showcased great elastic recovery abilities, with strain recovery values ranging from 72% to 85%. In contrast, the polyethylene produced by Ni4 displayed notably inferior tensile strength (0.16 MPa) and tensile recovery (43%). To the best of our knowledge, this study represents the inaugural utilization of a nickel iminopyridyl catalyst in the preparation of a polyethylene thermoplastic elastomer.