化学•材料最新文献

{"title":"K_<i>a</i>-Band Rotational Spectroscopy of Succinimide and N-Chlorosuccinimide.","authors":"Chisom A Dim, Caroline Sorrells, Alicia O Hernandez-Castillo, Kyle N Crabtree","doi":"10.1021/acs.jpca.4c06004","DOIUrl":"10.1021/acs.jpca.4c06004","url":null,"abstract":"<p><p>Succinimide and its derivatives are cyclic five-membered rings that appear in a variety of natural products and are widely used in organic synthesis. From a structural standpoint, succinimide contains an NH group in the ring which interacts with two adjacent carbonyl groups, pushing the ring structure toward planarity at the expense of increasing ring strain and eclipsing interactions among the out-of-plane hydrogen atoms in the two CH₂ groups. Previous quantum chemical calculations at different levels of theory have predicted both a nonplanar <i>C</i>₂ structure and a planar <i>C</i>_2<i>v</i> structure, the latter of which is the most consistent with gas-phase electron diffraction measurements. Here, we report the pure rotational spectra of succinimide and N-chlorosuccinimide in the 26.5-40.0 GHz range using chirped-pulse Fourier transform microwave spectroscopy, supported by coupled cluster and density functional theory quantum chemical calculations. The spectra were fit to Watson's A-reduced effective Hamiltonian, including both ³⁵Cl and ³⁷Cl isotopologues of N-chlorosuccinimide as well as the N and Cl quadrupole hyperfine interactions. On the basis of the agreement with quantum chemical calculations and the measured inertial defects, we find that the rotational spectra are consistent with a planar ring structure, with a maximum out-of-plane angle of ≤5°.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142556663","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":"Fluorescence Enhancement of Nonemissive Monodeprotonated Luteolin in a Poly(vinyl alcohol) Film.","authors":"Weili Wang, Yan Liu, Xiaolan Cheng, Qin Yu, Siyu Hou, Jie Zhao, Jian Luo","doi":"10.1021/acs.jpcb.4c06452","DOIUrl":"10.1021/acs.jpcb.4c06452","url":null,"abstract":"<p><p>Solid polymer matrixes can modulate the electronic states of embedded chromophores and have been widely used in flexible optoelectronic and optical materials. Luteolin is one of the most common natural flavonoids, and its neutral and monodeprotonated forms are nonemissive in aqueous solution induced by ultrafast excited-state proton transfer (ESPT) followed by nonradiative relaxation. In this study, we have incorporated luteolin into poly(vinyl alcohol) (PVA) films and studied their fluorescence behaviors. Neutral and one monodeprotonated luteolin coexist in the PVA film. Weak steady-state fluorescence of neutral luteolin peaking at about 440 nm is observed for the first time. In addition, the monodeprotonated luteolin in PVA film exhibits obvious fluorescence peaking at 500 nm, with a fluorescence quantum yield of as high as 0.4 and a fluorescence lifetime of as long as 2.4 ns. Time-dependent density functional theory calculations have determined that the ESPT of neutral luteolin is barrierless but that of monodeprotonated luteolin needs to surmount a barrier, explaining their distinct emission properties. These results indicate the modulation ability of the PVA film in both ground-state deprotonation and ESPT, broadening the application areas of the solid polymer matrix.</p>","PeriodicalId":60,"journal":{"name":"The Journal of Physical Chemistry B","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142556666","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":"Wave Function Localization Reduces the Bandgap of Disordered Double Perovskite Cs₂AgBiBr₆.","authors":"Dongyu Liu, Bayan Amer Abzakh, Elena A Kazakova, Dmitrii A Abrameshin, Pavel A Troshin, Run Long, Andrey S Vasenko","doi":"10.1021/acs.jpclett.4c02946","DOIUrl":"10.1021/acs.jpclett.4c02946","url":null,"abstract":"<p><p>Double perovskite Cs₂AgBiBr₆ is a promising alternative to lead-based perovskites with excellent stability and attractive optoelectronic properties. However, a relatively large bandgap severely limits its performance in many applications such as solar cells and photodetectors. It has been reported that a random distribution of Ag and Bi atoms in Cs₂AgBiBr₆ effectively reduces its bandgap without introducing dopants or impurities, while the mechanism remains unclear. Here, using density functional theory calculations, we demonstrate that the Ag-Bi disorder in Cs₂AgBiBr₆ generates localized electronic states as band edges to regulate the bandgap. The disordered structures segregate Ag and Bi atoms in the lattice, and the formed homoatomic clusters lead to wave function localization. Moreover, the bandgap decrease exhibits a non-monotonic dependence on the degree of disorder. Our results are comparable with experimental observations and provide crucial insights into understanding the order-disorder transition in double perovskites.</p>","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":null,"pages":null},"PeriodicalIF":4.8,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142566370","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":"Evidence for Nanostructures of at Least 20 nm in a Phosphonium Ionic Liquid at Room Temperature Using Fluorescence Correlation Spectroscopy.","authors":"Bala Gopal Maddala, Jaladhar Mahato, Ian T Morgan, Seth A Larson, Jayme A Brickley, Jared L Anderson, Emily A Smith, Xueyu Song, Jacob W Petrich","doi":"10.1021/acs.jpcb.4c04950","DOIUrl":"10.1021/acs.jpcb.4c04950","url":null,"abstract":"<p><p>Fluorescence correlation spectroscopy (FCS) measurements are performed on the ionic liquid (IL), tetradecyl(trihexyl) phosphonium chloride, [P66614⁺][Cl^-], using fluorescent probes of varying sizes: ATTO 532, ∼2 nm; and 20- and 40 nm fluorescent beads. The fluorescence correlation function, <i>G</i>(<i>t</i>), is analyzed in terms of a distribution of diffusion coefficients using a maximum entropy method (MEM). For ATTO 532 and the 20 nm beads, the fit to <i>G</i>(<i>t</i>) yields two well-defined distributions; for the 40 nm beads, however, only one is obtained. These results are consistent with the existence of two nanodomains whose size is greater than or equal to 20 nm and less than 40 nm. The origin of such nanodomains is attributed to a liquid-liquid phase transition. Other groups have observed liquid-liquid phase transitions experimentally in a number of systems, including [P66614⁺][Cl^-]. We suggest that because large regions (i.e., greater than 1-2 nm) resulting from the liquid-liquid phase transition would be expected to have different properties, such as viscosity, and because their presence would necessarily increase the number of interfaces in the IL, these regions may provide an explanation for the exceptional behavior of ILs in various separation systems.</p>","PeriodicalId":60,"journal":{"name":"The Journal of Physical Chemistry B","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142575455","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":"Structural Properties of [N1888][TFSI] Ionic Liquid: A Small Angle Neutron Scattering and Polarizable Molecular Dynamics Study.","authors":"Shehan M Parmar, William Dean, Changwoo Do, James F Browning, Jeffrey M Klein, Burcu E Gurkan, Jesse G McDaniel","doi":"10.1021/acs.jpcb.4c06255","DOIUrl":"10.1021/acs.jpcb.4c06255","url":null,"abstract":"<p><p>In this study, we investigate the quaternary ammonium-based ionic liquid (QAIL), methyltrioctylammonium bis(trifluoromethylsulfonyl)imide, [N₁₈₈₈][TFSI], utilizing small angle neutron scattering (SANS) measurements and polarizable molecular dynamics (MD) simulations to characterize the short- and long-range liquid structure. Scattering structure factors show signatures of three length scales in reciprocal space indicative of alternating polarity (<i>k</i> ∼ 0.44 Å^-1), charge (<i>k</i> ∼ 0.75 Å^-1), and neighboring or adjacent (<i>k</i> ∼ 1.46 Å^-1) domains. Excellent agreement between simulation and experimental scattering structure factors validates various simulation analyses that provide detailed atomistic characterization of the different length scale correlations. The first solvation shell structure is illustrated by obtaining radial, angular, dihedral, and combined distribution functions, where two dominant spatial motifs, N⁺···N^- and N⁺···O^-, compete for optimal packing around the polar head of the [N₁₈₈₈]⁺ cation. Intermediate and long-range structures are governed by the balance between local electroneutrality and octyl chain networking, respectively. By computing the charge-correlation structure factor, <i>S</i>_<i>ZZ</i>, and the spatial extent of the octyl chain network using graph theory, the bulk-phase structure of [N₁₈₈₈][TFSI] is characterized in terms of electrostatic screening and apolar domain formation length scales.</p>","PeriodicalId":60,"journal":{"name":"The Journal of Physical Chemistry B","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142575463","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":"Formation of β-U₃O₈ from UCl₃ Salt Compositions under Oxygen Exposure.","authors":"Benjamin W Tuffy, Nancy R Birkner, Juliano Schorne-Pinto, Ryan C Davis, Amir M Mofrad, Clara M Dixon, Mina Aziziha, Matthew S Christian, Timothy J Lynch, Maxwell T Bartlett, Theodore M Besmann, Kyle S Brinkman, Wilson K S Chiu","doi":"10.1021/acs.jpcb.4c02776","DOIUrl":"10.1021/acs.jpcb.4c02776","url":null,"abstract":"<p><p>Complementary X-ray absorption fine structure (XAFS) and Raman spectroscopy studies were conducted on various UCl₃ concentrations in alkali chloride salt compositions. The samples were 5 mol % UCl₃ in LiCl (S1), 5 mol % UCl₃ in KCl (S2), 5 mol % UCl₃ in LiCl-KCl eutectic (S4), 50 mol % UCl₃ in KCl (S5), and 20 mol % UCl₃ in KCl (S6) molar concentrations. Samples were heated to 800 °C and allowed to cool to room temperature with measurements performed at selected temperatures; the highest temperatures showed the most stability and will be primarily referenced for conclusions. The processing and interpretation of the Raman and extended X-ray absorption fine structure (EXAFS) peaks revealed several uranium-oxygen bond lengths and symmetries in the samples before, during, and after heating. Based on published thermodynamic data of similar systems, X-ray absorption fine structure spectroscopy, and identification of Raman peaks, a β variation of α-U₃O₈, typical at room temperature, is the suspected dominant phase of all samples at high temperatures (800 °C). In the existing literature, this β structure of U₃O₈ was synthesized by slow cooling of uranium oxides from 1350 °C. This paper suggests the rapid formation of the compound due to the decomposition of the uranium chlorides or oxychlorides at increasing temperatures and O₂ reaction kinetics.</p>","PeriodicalId":60,"journal":{"name":"The Journal of Physical Chemistry B","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142580960","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":"Explicit Configurational Entropy of Mixing in Molecular Dynamics Simulations.","authors":"T Hanke, A L Upterworth, D Sebastiani","doi":"10.1021/acs.jpclett.4c02819","DOIUrl":"10.1021/acs.jpclett.4c02819","url":null,"abstract":"<p><p>The entropy of mixing of a multicomponent system of particles is a simple expression of the molar fractions for the equilibrium state, but its intermediate values for transient (nonequilibrium) states can not be calculated directly from the particle coordinates so far. We propose a simple expression for the configurational entropy of mixing based solely on the set of instantaneous coordinates, which is suitable for the on-the-fly determination of the degree of mixing along a molecular dynamics trajectory. We illustrate the applicability of our scheme with the example of several molecular mixtures that exhibit fast and slow mixing and demixing processes within a molecular dynamics simulation.</p>","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":null,"pages":null},"PeriodicalIF":4.8,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142581018","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":"Luminescence and Transport Behavior in Incommensurately Modulated CaGd₂(MoO₄)₄:Yb/Er.","authors":"Yinghan Wang, Zeyue Zhang, Guohong Cai, Jingxie Xiong, Zhengren Tao, Chunhai Wang, Junliang Sun, Shi Ye","doi":"10.1021/acs.jpclett.4c02554","DOIUrl":"10.1021/acs.jpclett.4c02554","url":null,"abstract":"<p><p>The phenomenon of thermal quenching of luminescence can significantly compromise the efficiency of luminescent materials, a process accompanied by the generation of substantial phonon populations. While plenty of models for elucidating this behavior have been proposed, the crucial role of phonon transport has largely been neglected, particularly in the enigmatic incommensurate scheelite structure with good luminescence performance. In this study, we delve into the thermal quenching dynamics of the near-infrared emission in the incommensurately modulated CaGd₂(MoO₄)₄:Yb/Er system. Our comprehensive investigation reveals distinct evolutionary patterns in electrical conductivity, luminescence intensity, thermal conductivity, and Raman scattering at varying temperature regimes. Notably, we have determined that thermally induced ion migration, occurring above ∼300 °C, serves as a pivotal trigger for the activation of all phonons and the enhancement of phonon-defect scattering within this incommensurate framework. This phenomenon not only diminishes the thermal conductivity but also accelerates the multiphonon relaxation of the Er³⁺ emission levels, culminating in a marked thermal quenching of luminescence. This work illuminates the thermal quenching mechanism of luminescence by focusing on phonon scattering dynamics, providing critical insights for the design of thermally robust near-infrared luminescent materials, which are essential for the advancement of optical amplification systems.</p>","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":null,"pages":null},"PeriodicalIF":4.8,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142581022","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":"Visible-Light-Mediated Three-Component Decarboxylative Coupling Reactions for the Synthesis of 4-Alkylpyridines","authors":"Ai Wang, Yijian Ma, Jia-Hui Jin, Le-Quan Wang, Dan-Dan Li, Zi-Wei Xi, Chengshuo Shen, Yong-Miao Shen","doi":"10.1021/acs.joc.4c02037","DOIUrl":"https://doi.org/10.1021/acs.joc.4c02037","url":null,"abstract":"4-Alkylation of pyridines has been achieved by a photocatalyzed three-component reaction of an olefin, an aryloxyacetic acid, and cyanopyridine using Ir[dF(CF₃)ppy]₂(dtbbpy)PF₆ as a photocatalyst. In this way, a new type of 4-alkylpyridines bearing aryl and aryloxy substituents on the phenyl was accessed with potential pharmaceutical value. In addition to mild reaction conditions, the method has several other advantages, including a multicomponent one-pot protocol, good functional group tolerance, and easy amplification of the reaction scale. The reaction mechanism has been clarified by control experiments and computation of the reaction energy profile.","PeriodicalId":57,"journal":{"name":"The Journal of Organic Chemistry","volume":null,"pages":null},"PeriodicalIF":4.354,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142610386","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":"Field Trials of an Autonomous eDNA Sampler in Lotic Waters","authors":"Scott D. George, Adam J. Sepulveda, Patrick R. Hutchins, David S. Pilliod, Katy E. Klymus, Austen C. Thomas, Ben C. Augustine, Chany C. Huddleston Adrianza, Devin N. Jones, Jacob R. Williams, Eric G. Leinonen","doi":"10.1021/acs.est.4c04970","DOIUrl":"https://doi.org/10.1021/acs.est.4c04970","url":null,"abstract":"Environmental DNA (eDNA) analysis has become a transformative technology, but sample collection methods lack standardization and sampling at effective frequencies requires considerable field effort. Autonomous eDNA samplers that can sample water at high frequencies offer potential solutions to these problems. We present results from four case studies using a prototype autonomous eDNA sampler as part of the U.S. Geological Survey’s Rapid Environmental eDNA Assessment and Deployment Initiative &amp; Network (READI-Net) project. These case studies involved short-term deployments of an eDNA autosampler (Smith-Root) across a range of riverine habitats with the objectives of (a) identifying what insights could be gained from high-frequency autosampling and (b) benchmarking these autosamples against manually collected samples. The high frequency autosampling revealed high temporal variability of eDNA concentrations and provided valuable insights about eDNA associations with environmental covariates, such as discharge and turbidity. Benchmarking assessments indicated autosamples had similar detection rates to manual samples and obtained similar or greater eDNA quantities. We did find minimal carryover contamination in autosampler field controls. We conclude that eDNA autosamplers have potential to improve freshwater biosurveillance by reducing logistical sampling barriers, standardizing collection methods, and clarifying the influence of environmental covariates on eDNA results.","PeriodicalId":36,"journal":{"name":"环境科学与技术","volume":null,"pages":null},"PeriodicalIF":9.028,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142610493","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}