Catalyst-Free C(sp²)‑H Borylation through Aryl Radical Generation from Thiophenium Salts via Electron Donor–Acceptor Complex Formation

Aryl borates lie at the heart of carbon–carbon bond couplings, and they are widely applied to the synthesis of functional materials, pharmaceutical compounds, and natural products. Currently, synthetic methods for aryl borates are mostly limited to metal-catalyzed routes, and nonmetallic strategies remain comparatively underdeveloped. Herein, we report a mild, scalable, visible-light-induced cross-coupling between aryl dibenzothiophenium triflate salts and bis(catecholato)-diboron for the construction of C–B bonds in the absence of base, transition metal–ligand complex, or photoredox catalyst. Mechanistic studies reveal that this transformation is achieved through an electron donor–acceptor (EDA) complex activation in the absence of a catalyst. The mild reaction conditions allow the preparation of aromatic borates in good yields with excellent functional group tolerance. This photochemical protocol was also successfully applied to the late-stage modification of natural products and the synthesis of a drug intermediate, greatly demonstrating broadened utility

Co Nanoparticles Encapsulated in N‑Doped Carbon Nanosheets: Enhancing Oxygen Reduction Catalysis without Metal–Nitrogen Bonding

It is known that introducing metal nanoparticles (e.g., Fe and Co) into N-doped carbons can enhance the activity of N-doped carbons toward the oxygen reduction reaction (ORR). However, introducing metals into N-doped carbons inevitably causes the formation of multiple active sites. Thus, it is challenging to identify the active sites and unravel mechanisms responsible for enhanced ORR activity. Herein, by developing a new N-heterocyclic carbene (NHC)–Co complex as the nitrogen- and metal-containing precursor, we report the synthesis of N-doped carbon nanosheets embedded with Co nanoparticles as highly active ORR catalysts without direct metal–nitrogen bonding. Electrochemical measurements and X-ray absorption spectroscopy indicate that the carbon–nitrogen sites surrounding Co nanoparticles are responsible for the observed ORR activity and stability. Density functional theory calculations further reveal that Co nanoparticles could facilitate the protonation of O₂ and thus promote the ORR activity. These results provide new prospects in the rational design and synthesis of heteroatom-doped carbon materials as non-precious-metal catalysts for various electrochemical reactions

Supplementary document for Broadband ASE source-enabled self-homodyne DA-RoF fronthaul using cascaded SOAs and multicore fiber - 6853676.pdf

Supplemental Documen

Sr₂Mn₃Sb₂O₂ Type Oxyselenides: Structures, Magnetism, and Electronic Properties of Sr₂<i>A</i>O₂<i>M</i>₂Se₂ (<i>A</i>=Co, Mn; <i>M</i>=Cu, Ag)

Four new oxyselenides with nominal formula Sr₂<i>A</i>O₂<i>M</i>₂Se₂ (<i>A</i>=Co, Mn; <i>M</i>=Cu, Ag) have been synthesized. They all crystallize in an <i>I</i>4/<i>mmm</i> space group and consist of alternating perovskite-like (Sr₂<i>A</i>O₂)²⁺ blocks and antiflourie (<i>M</i>₂Se₂)^2‑ layers, which are relatively rare layered oxyselenides reported so far that are isostructural to Sr₂Mn₃Sb₂O₂. From powder X-ray diffraction data, compounds Sr₂CoO₂Cu₂Se₂ and Sr₂CoO₂Ag₂Se₂ are found near stoichiometric, whereas Sr₂MnO₂Cu_2‑δSe₂ and Sr₂MnO₂Ag_2‑δSe₂ possess substantial copper or silver vacancies (δ≈0.5), consistent with their oxysulfide analogues. X-ray photoelectron spectroscopy measurements indicate the readily oxidization of Mn²⁺ ions should be responsible for the occurrence of Cu/Ag vacancies. The rigid (Sr₂<i>A</i>O₂)²⁺ blocks within these compounds constrain the basal lattice parameters in the <i>ab</i> plane and result in largely deformed tetrahedral sites for the large silver ions. Magnetic susceptibility measurements of Sr₂CoO₂<i>M</i>₂Se₂ (<i>M</i>=Cu, Ag) show complex antiferromagnetic transitions, while Sr₂MnO₂<i>M</i>_2‑δSe₂ (<i>M</i>=Cu, Ag) show high-temperature Curie–Weiss behavior, followed by low-temperature antiferromagnetic transitions at 54 K and 67 K, respectively. Except for Sr₂MnO₂Ag_2‑δSe₂, the other three compounds exhibit p-type semiconducting transport properties, with the measured resistivities several orders lower than their oxysulfide analogues. Hall measurement reveals high mobilities of Sr₂CoO₂<i>M</i>₂Se₂ (<i>M</i>=Cu, Ag) compounds at room temperature. The unusually small optical band gaps (∼0.07 eV) of Sr₂CoO₂Cu₂Se₂, Sr₂CoO₂Ag₂Se₂, and Sr₂MnO₂Cu_2‑δSe₂ are also reported

Sr₂Mn₃Sb₂O₂ Type Oxyselenides: Structures, Magnetism, and Electronic Properties of Sr₂<i>A</i>O₂<i>M</i>₂Se₂ (<i>A</i>=Co, Mn; <i>M</i>=Cu, Ag)

Four new oxyselenides with nominal formula Sr₂<i>A</i>O₂<i>M</i>₂Se₂ (<i>A</i>=Co, Mn; <i>M</i>=Cu, Ag) have been synthesized. They all crystallize in an <i>I</i>4/<i>mmm</i> space group and consist of alternating perovskite-like (Sr₂<i>A</i>O₂)²⁺ blocks and antiflourie (<i>M</i>₂Se₂)^2‑ layers, which are relatively rare layered oxyselenides reported so far that are isostructural to Sr₂Mn₃Sb₂O₂. From powder X-ray diffraction data, compounds Sr₂CoO₂Cu₂Se₂ and Sr₂CoO₂Ag₂Se₂ are found near stoichiometric, whereas Sr₂MnO₂Cu_2‑δSe₂ and Sr₂MnO₂Ag_2‑δSe₂ possess substantial copper or silver vacancies (δ≈0.5), consistent with their oxysulfide analogues. X-ray photoelectron spectroscopy measurements indicate the readily oxidization of Mn²⁺ ions should be responsible for the occurrence of Cu/Ag vacancies. The rigid (Sr₂<i>A</i>O₂)²⁺ blocks within these compounds constrain the basal lattice parameters in the <i>ab</i> plane and result in largely deformed tetrahedral sites for the large silver ions. Magnetic susceptibility measurements of Sr₂CoO₂<i>M</i>₂Se₂ (<i>M</i>=Cu, Ag) show complex antiferromagnetic transitions, while Sr₂MnO₂<i>M</i>_2‑δSe₂ (<i>M</i>=Cu, Ag) show high-temperature Curie–Weiss behavior, followed by low-temperature antiferromagnetic transitions at 54 K and 67 K, respectively. Except for Sr₂MnO₂Ag_2‑δSe₂, the other three compounds exhibit p-type semiconducting transport properties, with the measured resistivities several orders lower than their oxysulfide analogues. Hall measurement reveals high mobilities of Sr₂CoO₂<i>M</i>₂Se₂ (<i>M</i>=Cu, Ag) compounds at room temperature. The unusually small optical band gaps (∼0.07 eV) of Sr₂CoO₂Cu₂Se₂, Sr₂CoO₂Ag₂Se₂, and Sr₂MnO₂Cu_2‑δSe₂ are also reported

Potential of fluorescent nanoprobe in diagnosis and treatment of Alzheimer’s disease Supplementary figures nnm-2022-0022

Alzheimer’s disease (AD) is well known for its insidious nature, slow progression and high incidence as a neurodegenerative disease. In the past, diagnosis of AD mainly depended on analysis of a patient’s cognitive ability and behavior. Without a unified standard for analysis methods, this is prone to produce incorrect diagnoses. Currently, definitive diagnosis mainly relies on histopathological examination. Because of the advantages of precision, noninvasiveness, low toxicity and high spatiotemporal resolution, fluorescent nanoprobes are suitable for the early diagnosis of AD. This review summarizes the research progress of different kinds of fluorescent nanoprobes for AD diagnosis and therapy in recent years and provides an outlook on the development prospects of fluorescent nanoprobes.</p

Enhanced Raman Scattering on In-Plane Anisotropic Layered Materials

Surface-enhanced Raman scattering (SERS) on two-dimensional (2D) layered materials has provided a unique platform to study the chemical mechanism (CM) of the enhancement due to its natural separation from electromagnetic enhancement. The CM stems from the charge interactions between the substrate and molecules. Despite the extensive studies of the energy alignment between 2D materials and molecules, an understanding of how the electronic properties of the substrate are explicitly involved in the charge interaction is still unclear. Lately, a new group of 2D layered materials with anisotropic structures, including orthorhombic black phosphorus (BP) and triclinic rhenium disulfide (ReS₂), has attracted great interest due to their unique anisotropic electrical and optical properties. Herein, we report a unique anisotropic Raman enhancement on few-layered BP and ReS₂ using copper phthalocyanine (CuPc) molecules as a Raman probe, which is absent on isotropic graphene and h-BN. According to detailed Raman tensor analysis and density functional theory calculations, anisotropic charge interactions between the 2D materials and molecules are responsible for the angular dependence of the Raman enhancement. Our findings not only provide new insights into the CM process in SERS, but also open up new avenues for the exploration and application of the electronic properties of anisotropic 2D layered materials

Optical Anisotropy of Black Phosphorus in the Visible Regime

The striking in-plane anisotropy remains one of the most intriguing properties for the newly rediscovered black phosphorus (BP) 2D crystals. However, because of its rather low-energy band gap, the optical anisotropy of few-layer BP has been primarily investigated in the near-infrared (NIR) regime. Moreover, the essential physics that determine the intrinsic anisotropic optical property of few-layer BP, which is of great importance for practical applications in optical and optoelectronic devices, are still in the fancy of theory. Herein, we report the direct observation of the optical anisotropy of few-layer BP in the visible regime simply by using polarized optical microscopy. On the basis of the Fresnel equation, the intrinsic anisotropic complex refractive indices (<i>n</i>–<i>i</i>κ) in the visible regime (480–650 nm) were experimentally obtained for the first time using the anisotropic optical contrast spectra. Our findings not only provide a convenient approach to measure the optical constants of 2D layered materials but also suggest a possibility to design novel BP-based photonic devices such as atom-thick light modulators, including linear polarizer, phase plate, and optical compensator in a broad spectral range extending to the visible window