化学•材料最新文献

{"title":"Strong Magneto-Optical Responses of an Ensemble of Defect-Bound Excitons in Ambient Exposed WS2 and WSe2 Monolayers","authors":"Frederico B. Sousa, Alessandra Ames, Mingzu Liu, Pedro L. Gastelois, Vinícius A. Oliveira, Da Zhou, Matheus J. S. Matos, Helio Chacham, Mauricio Terrones, Marcio D. Teodoro, Leandro M. Malard","doi":"10.1021/acs.jpcc.5c00951","DOIUrl":"https://doi.org/10.1021/acs.jpcc.5c00951","url":null,"abstract":"Transition metal dichalcogenide (TMD) monolayers present a singular coupling in their spin and valley degrees of freedom. Moreover, by applying an external magnetic field it is possible to break the energy degeneracy between their K and −K valleys. This valley Zeeman effect opens the possibility of controlling and distinguishing the spin and valley characters of charge carriers in TMDs by their optical transition energies, making these materials promising for the next generation of spintronic and photonic devices. However, the free excitons of pristine TMD monolayers present a moderate valley Zeeman splitting of ≈0.23 meV/T. Therefore, alternative excitonic states with higher magnetic responses are mandatory for application purposes. Here, we investigate the magneto-optical properties of ambient exposed WS₂ and WSe₂ monolayers by circularly polarized magneto-photoluminescence experiments at cryogenic temperatures. A broad lower energy photoluminescence emission related to an ensemble of defects is observed, presenting remarkable valley-related splittings of ≈1.45 meV/T and ≈1.11 meV/T for WS₂ and WSe₂ monolayers, respectively. In addition, we report a significant spin polarization of charge carriers in the defect midgap states induced by the external magnetic field. We explain this spin-polarized population and enhanced valley-related splitting in terms of imbalanced spin-flip transitions, leading to a magnetic field-dependent distribution of charge carriers in multiple defect levels. This effect, together with the individual Zeeman shiftings of the midgap states, explains the strong magneto-optical responses observed. Our work uncovers the singular potential of manipulating the light emission of ambient exposed TMD monolayers by an external magnetic field.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"55 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143876327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Total Synthesis of the Melodinus Alkaloid (±)-Melohemsine K","authors":"Shanhao Lin, Hao Jing, Jinbo Duan, Jing Fang, Gaoyuan Zhao, Xingang Xie, Huilin Li, Xuegong She","doi":"10.1021/acs.joc.5c00545","DOIUrl":"https://doi.org/10.1021/acs.joc.5c00545","url":null,"abstract":"The first total synthesis of the novel <i>Melodinus</i> alkaloid melohemsine K is described in five steps from known precursors. The key reaction of the synthesis is a tandem enamine formation/retro-aza-Michael reaction/Diels–Alder cycloaddition/intramolecular lactamization reaction cascade between indole-fused azepine and aldehyde precursors, forging the critical CDE tricyclic system. The synthesis provided a general approach to novel <i>Melodinus</i> alkaloids.","PeriodicalId":57,"journal":{"name":"Journal of Organic Chemistry","volume":"12 1","pages":""},"PeriodicalIF":4.354,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143872918","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Accountability Assessment of Source-Specific Impacts of Regulations on Emissions and Air Quality Using Positive Matrix Factorization","authors":"Ziqi Gao, Eric J. Mei, Xin He, Stefanie Ebelt, David Q. Rich, Armistead G. Russell","doi":"10.1021/acs.est.4c12511","DOIUrl":"https://doi.org/10.1021/acs.est.4c12511","url":null,"abstract":"Emission controls targeting electric generating units (EGUs) and mobile sources have been implemented for decades to mitigate PM_2.5 concentrations. Impacts of emission controls on source-apportioned PM_2.5 concentrations (diesel/gasoline vehicles, biomass burning, secondary nitrate, secondary sulfate, soil/road dust, and residual oil estimated via positive matrix factorization) across three U.S. highly urbanized regions─Atlanta, New York City, and the South Coast Air Basin (SoCAB)─from 2005 to 2019 were evaluated. We considered major controls on EGUs, mobile sources, ports, and heating fuel. Daily counterfactual source-apportioned PM_2.5 concentrations without emission controls were estimated based on meteorological indicators and counterfactual emissions using the generalized additive model. Results indicate that emission controls reduced the PM_2.5 concentrations by 65–85% across all regions. Secondary sulfate concentrations without EGU controls would be 4.8 times higher, and diesel-vehicle-related PM_2.5 would increase 6.8 times without mobile controls in Atlanta. Secondary inorganic aerosols in New York City would increase 5-fold from 1.92 to 10.5 μg/m³, shifting the dominant PM_2.5 contributors. Seasonal trends in the counterfactual PM_2.5 concentrations were similar to the actual trends, but the peaks in the counterfactual scenario were clearer than those with emission controls.","PeriodicalId":36,"journal":{"name":"环境科学与技术","volume":"40 1","pages":""},"PeriodicalIF":9.028,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143866562","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pressure- and Temperature-Dependence of Polar Nanoregions in KTN40 (KTa0.6Nb0.4O3) and KNbO3","authors":"Tim H. Reuter, Lkhamsuren Bayarjargal, Daniel Rytz, Sebastian Schwung, Victor Milman, Björn Winkler","doi":"10.1021/acs.jpcc.5c01075","DOIUrl":"https://doi.org/10.1021/acs.jpcc.5c01075","url":null,"abstract":"We investigated the pressure- and temperature-dependent phase transitions in KTN₄₀ (KTa_0.6Nb_0.4O₃) and KNbO₃, two members of the perovskite-type ferroelectric solid solution system KTN (KTa_<i>x</i>Nb_1–<i>x</i>O₃), by heat capacity measurements, Raman spectroscopy, and second harmonic generation (SHG). The phase transition temperatures for the rhombohedral → orthorhombic → tetragonal → cubic sequence in KTN₄₀ were determined to be 180(2) K, 225(2) K, and 295(2) K, respectively, by heat capacity measurements. For KNbO₃, SHG measurements revealed orthorhombic → tetragonal → cubic transitions at 460(3) K and 720(3) K. In both compounds, SHG experiments indicated the presence of polar nanoregions within the cubic phase above the Curie temperatures of KTN₄₀ and KNbO₃. The dynamics and stability fields of these polar nanoregions were analyzed, resulting in Burns temperatures <i>T</i>_d of 510(5) K for KTN₄₀ and 1000(5) K for KNbO₃. Intermediate temperatures, <i>T</i>*, where polar nanoregions begin to merge into larger domains, were identified for KTN₄₀ and KNbO₃ to be 350(5) K and 775(5) K, respectively. The pressure-dependent tetragonal → cubic phase transition was observed at 1.3(1) GPa for KTN₄₀ and 15(0.5) GPa for KNbO₃ using SHG. SHG measurements further confirmed polar nanoregions occurring in the cubic phase above the Curie pressures of KTN₄₀ and KNbO₃. Burns pressures <i>p</i>_d were determined to be 6(1) GPa for KTN₄₀ and 24(1) GPa and intermediate pressures <i>p</i>* were found at 1.8(2) GPa and 17(1) GPa, respectively. The known phase boundaries in temperature- and pressure-dependent phase diagrams could be reproduced and extended and phase diagrams could be enhanced by the addition of stability fields of polar nanoregions. It could also be shown that the dynamics of the polar nanoregions depend on chemical composition, as temperature-induced polar nanoregions in KTN₄₀ appear to be smaller than in KNbO₃. In addition, this study contains thermodynamic data for KNbO₃, KTN₄₀ and KTaO₃. Based on the excess entropy for KTN₄₀, these show that the formation of solid solutions tends to be favored in the KTN system compared to segregation.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"23 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143872633","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spectroscopic Techniques for Renewable Energy","authors":"Linjuan Zhang*,&nbsp;Jian-Qiang Wang*,&nbsp;Scott Oliver* and Chao Jing*,&nbsp;","doi":"10.1021/acs.jpcc.5c0156310.1021/acs.jpcc.5c01563","DOIUrl":"https://doi.org/10.1021/acs.jpcc.5c01563https://doi.org/10.1021/acs.jpcc.5c01563","url":null,"abstract":"","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"129 16","pages":"7589–7590 7589–7590"},"PeriodicalIF":3.3,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143863085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Copper-Catalyzed Reductive Hydroamination of Alkenes and 1,3-Dienes with Nitroarenes","authors":"Zi-Heng Zhang, Shuang-Shuang Ma, Yuan-Yuan Jiang, Jin-Qing Lin, Bao-Hua Xu","doi":"10.1021/acs.joc.4c02150","DOIUrl":"https://doi.org/10.1021/acs.joc.4c02150","url":null,"abstract":"In this study, copper-catalyzed reductive hydroamination of alkenes and 1,3-dienes with nitroarenes was developed. Such umpolung hydroamination of unsaturated C═C double bonds exhibited Markovnikov selectivity, and the hydroamination of 1,3-dienes preferred 1,2-addition. Mechanistic studies suggested the system proceeds through a radical pathway with the concomitant activation of both substrates to nucleophilic alkyl radical species and electrophilic nitro-based intermediates, respectively. The attack of alkyl radical species on the N atom of nitro-based intermediates yielded the desired amines. However, this C–N cross-coupling strongly competed with the self-reduction of each species under such a system.","PeriodicalId":57,"journal":{"name":"Journal of Organic Chemistry","volume":"8 1","pages":""},"PeriodicalIF":4.354,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143867137","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spectroscopic Techniques for Renewable Energy","authors":"Linjuan Zhang, Jian-Qiang Wang, Scott Oliver, Chao Jing","doi":"10.1021/acs.jpcc.5c01563","DOIUrl":"https://doi.org/10.1021/acs.jpcc.5c01563","url":null,"abstract":"Published as part of &lt;i&gt;The Journal of Physical Chemistry C&lt;/i&gt; special issue “Spectroscopic Techniques for Renewable Energy”. Nowadays, in the face of escalating global energy demands and pressing environmental concerns, the necessity for developing sustainable energy solutions has become extremely urgent. Renewable energy sources, including hydrogen, carbon conversion, rechargeable batteries, and photovoltaics, have emerged as crucial components in achieving efficient energy conversion and storage. (1−5) However, the realization of this vision is hindered by significant scientific and technological challenges, particularly when it comes to understanding the catalytic processes. The lack of clarity on the underlying mechanisms of catalytic reactions significantly limits the advancement of efficiency and cost-effectiveness catalysts, thus impeding future industrial applications. To address these challenges, advanced spectroscopic techniques are essential for providing deep insight into the intricate processes governing energy-related catalysis (10.1021/acs.jpcc.4c05853). (6) This special issue aims to highlight the critical role that sophisticated spectroscopic methods play in investigating the mechanisms of energy conversion and storage. We focus on a range of cutting-edge spectroscopic methods, including Raman spectroscopy, X-ray absorption spectroscopy and X-ray diffraction (XRD), etc. for unraveling the complexities of catalytic processes. Among these techniques, XRD provides valuable information about the crystal structure of materials, essential for understanding the fundamental architecture of catalytic species (10.1021/acs.jpcc.4c05891, 10.1021/acs.jpcc.4c05992). Raman and infrared spectroscopy shed light on molecular vibrations, offering insights into material composition and chemical interactions (10.1021/acs.jpcc.4c03619, 10.1021/acs.jpcc.4c05826, 10.1021/acs.jpcc.4c05670). Leveraging synchrotron light sources, X-ray absorption and emission spectroscopy affords unparalleled resolution in characterizing the fine electronic structure of materials (10.1021/acs.jpcc.4c05526, 10.1021/acs.jpcc.4c00670, 10.1021/acs.jpcc.4c03528). Many other spectroscopic techniques such as UV–vis spectroscopy (10.1021/acs.jpca.4c04902), intensity-modulated photocurrent spectroscopy (10.1021/acs.jpcc.4c04819), mass spectroscopy (10.1021/acs.jpcc.4c03623), and X-ray photoelectron spectroscopy (10.1021/acs.jpcc.4c03480, 10.1021/acs.jpcc.4c03904, 10.1021/acs.jpcc.4c03034) also enable the identification of electronic states and structural properties, crucial for tailoring materials with optimal catalytic properties. It is worth noting that, in the realm of practical applications, the reaction environment and conditions often differ significantly from those present during lab testing. Traditional &lt;i&gt;ex-situ&lt;/i&gt; characterization can fall short of accurately representing the real catalytic reaction processes. Hence, the emphasis on &lt;i&gt;in situ&lt;/i&gt; and &lt;i&gt;operando&lt;/i&gt; ","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"17 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143867151","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Copper-Catalyzed and 1,3-Sulfonyl Migration Enabled Installation of Azaindoles in the Periphery of Aryl Rings: Synthesis of Sulfonylated Pyrrolo[2,3-b]quinolines and Investigation of Antimalarial Potency","authors":"Shivani Choudhary, Gayyur, Siddhant, Ashan Manhas, Ruchir Kant, Nayan Ghosh","doi":"10.1021/acs.joc.5c00170","DOIUrl":"https://doi.org/10.1021/acs.joc.5c00170","url":null,"abstract":"Herein, an atom efficient and one-pot protocol, offering a series of sulfonylated pyrrolo[2,3-<i>b</i>]quinolines via C–N, C–C, and C–S bond formation, has been developed with an inexpensive copper catalyst. Notably, the reaction proceeds via a double-annulation reaction followed by a 1,3-sulfonyl migration sequence. Moreover, the method is applicable to a broad range of 2-carbonylanilines. Furthermore, synthetic applications and the scale-up reaction highlight the utility potential of this protocol. In addition, the antimalarial property of sulfonylated pyrrolo[2,3-<i>b</i>]quinolines showed parasite inhibition without cytotoxic effects in mammalian cells.","PeriodicalId":57,"journal":{"name":"Journal of Organic Chemistry","volume":"75 1","pages":""},"PeriodicalIF":4.354,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143872920","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Imaging Ultraweak Photon Emission from Living and Dead Mice and from Plants under Stress","authors":"V. Salari, V. Seshan, L. Frankle, D. England, C. Simon, D. Oblak","doi":"10.1021/acs.jpclett.4c03546","DOIUrl":"https://doi.org/10.1021/acs.jpclett.4c03546","url":null,"abstract":"The phenomenon of biological ultraweak photon emission (UPE), that is, extremely low-intensity emission (10–10³ photons cm^–2 s^–1) in the spectral range of 200–1000 nm, has been observed in all living systems that have been examined. Here, we report experiments that exemplify the ability of novel imaging systems to detect variations in UPE for a set of physiologically important scenarios. We use electron-multiplying charge-coupled device (EMCCD) and charge-coupled device (CCD) cameras to capture single visible-wavelength photons with low noise and quantum efficiencies higher than 90%. Our investigation reveals significant contrast between the UPE from live vs dead mice. In plants, we observed that an increase in the temperature and injuries both caused an increase in UPE intensity. Moreover, chemical treatments modified the UPE emission characteristics of plants, particularly the application of a local anesthetic (benzocaine) to injury, which showed the highest emission among the compounds tested. As a result, UPE imaging provides the possibility of non-invasive label-free imaging of vitality in animals and the responses of plants to stress.","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":"69 1","pages":""},"PeriodicalIF":6.475,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143867100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fabrication of Surfactant-Free Mixed-Metal Nanocatalyst–Carbon Fiber Paper Composites via Pulsed Laser Grafting","authors":"Madeleine K. Wilsey, Teona Taseska, Lydia R. Schultz, Elena Perez, Astrid M. Müller","doi":"10.1021/acs.jpcc.5c00641","DOIUrl":"https://doi.org/10.1021/acs.jpcc.5c00641","url":null,"abstract":"We present a novel methodology for fabricating surfactant-free mixed-metal nanocatalyst–carbon fiber paper composites, demonstrating significant improvements in impedance, electrocatalytic activity, and long-term stability over laser synthesized drop cast analogues on carbon fiber paper or highly ordered pyrolytic graphite. Our innovative pulsed laser grafting technique is a versatile, one-step aqueous process that integrates nanoparticle generation with surface attachment on macroscopic solid supports, such as sheets, rather than being limited to powders, particulate supports, or organic solvents as in prior methods. It effectively addresses longstanding challenges with nanoparticle adhesion and electrical contact between nanoparticles and macroscopic electrodes, and it alleviates environmental concerns associated with organic solvents. Laser grafting eliminates laborious synthesis, separation, purification, and postsynthesis attachment steps, thus significantly reducing composite preparation time. We fabricated [NiFe]-(OH)₂–hydrophilic carbon fiber paper composites using aqueous nickel–iron nitrate solution. Low-fluence 532 nm nanosecond laser pulses minimized surface damage and facilitated effective metal ion excitation for nanoparticle assembly. SEM, EDX and XPS data revealed surface [NiFe]-(OH)₂ without carbon encapsulation and prominent Ni–C interactions. The pulsed laser grafted composites showed enhanced electrocatalytic performance for alkaline water oxidation and decreased material charge transfer resistance, compared to drop cast analogues, leading to improved electrical conductivity and mass activity. Additionally, they demonstrated exceptional long-term stability, overcoming common adhesion issues in conventional nanoparticle–support systems, marking a significant advancement in the manufacturing of multimetallic nanoparticle–support composites, with promising implications for electrochemistry and electrocatalysis technologies.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"10 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143867143","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}