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Red-to-Blue Triplet-Triplet Annihilation Upconversion for Calcium Sensing. 用于钙传感的红-蓝三重-三重湮灭上转换。
IF 4.8 2区 化学 Q2 CHEMISTRY, PHYSICAL Pub Date : 2024-07-15 DOI: 10.1021/acs.jpclett.4c01528
Valeriia D Andreeva, Irene Regeni, Tingxiang Yang, Anna Elmanova, Martin Presselt, Benjamin Dietzek-Ivanšić, Sylvestre Bonnet

Triplet-triplet annihilation upconversion is a bimolecular process converting low-energy photons into high-energy photons. Here, we report a calcium-sensing system working via triplet-triplet annihilation (TTA) upconverted emission. The probe itself was obtained by covalent conjugation of a blue emitter, perylene, with a calcium-chelating moiety, and it was sensitized by the red-light-absorbing photosensitizer palladium(II) tetraphenyltetrabenzoporphyrin (PdTPTBP). Sensing was selective for Ca2+ and occurred in the micromolar domain. In deoxygenated conditions, the TTA upconverted luminescence gradually appeared upon adding an increasing concentration of calcium ions, to reach a maximum upconversion quantum yield of 0.0020.

三重-三重湮灭上转换是一种将低能光子转换为高能光子的双分子过程。在这里,我们报告了一种通过三重-三重湮灭(TTA)上转换发射工作的钙传感系统。探针本身是通过蓝色发射体过江龙与钙螯合基团共价共轭得到的,并通过吸收红光的光敏剂四苯基四苯并卟啉钯(II)(PdTPTBP)敏化。对 Ca2+ 的感应是选择性的,并发生在微摩尔域。在脱氧条件下,当加入的钙离子浓度增加时,TTA 上转换发光逐渐出现,达到 0.0020 的最大上转换量子产率。
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引用次数: 0
Unveiling the Role of Spin Currents on the Giant Rashba Splitting in Single-Layer WSe2 揭示自旋电流对单层 WSe2 中巨型拉什巴分裂的作用
IF 6.475 2区 化学 Q2 CHEMISTRY, PHYSICAL Pub Date : 2024-07-15 DOI: 10.1021/acs.jpclett.4c01607
Alberto Boccuni, Bárbara Maria Teixeira Costa Peluzo, Filippo Bodo, Giacomo Ambrogio, Jefferson Maul, Davide Mitoli, Giovanni Vignale, Stefano Pittalis, Elfi Kraka, Jacques K. Desmarais, Alessandro Erba
The Rashba spin splitting in uniaxial, inversion-asymmetric materials has attracted considerable interest for spintronic applications. The most widely used theoretical framework to model such states is Kohn–Sham density functional theory (DFT) in combination with standard (semi)local exchange–correlation density functional approximations (DFAs). However, in the presence of spin–orbit coupling, DFT misses contributions due to modification of the many-body interaction by spin currents J⃗. Inclusion of the latter effects requires a spin current DFT (SCDFT) formulation, which is seldom considered. We investigate the giant Rashba splitting in single-layer WSe2, and we quantify the effect of including spin currents in DFAs of the SCDFT. Crucially, we show that SCDFT allows fully capturing the giant Rashba band splitting in single-layer WSe2, otherwise previously systematically underestimated by standard (semi)local DFAs within the DFT framework. We find the inclusion of J⃗ on the DFA increases the Rashba splitting by about 20%.
单轴反转不对称材料中的拉什巴自旋分裂在自旋电子应用方面引起了极大的兴趣。最广泛应用的理论框架是结合标准(半)局部交换相关密度泛函近似(DFAs)的 Kohn-Sham 密度泛函理论(DFT)来模拟这种状态。然而,在存在自旋轨道耦合的情况下,DFT 会忽略由于自旋电流 J⃗ 对多体相互作用的修正而产生的贡献。要将后一种效应包括在内,需要使用自旋电流 DFT(SCDFT)公式,而这种公式很少被考虑。我们研究了单层 WSe2 中的巨型 Rashba 分裂,并量化了将自旋电流纳入 SCDFT DFA 的影响。最重要的是,我们发现 SCDFT 可以完全捕捉到单层 WSe2 中的巨型 Rashba 带分裂,而之前在 DFT 框架内的标准(半)局部 DFA 则系统性地低估了这种分裂。我们发现在 DFA 中加入 J⃗ 会使 Rashba 带分裂增加约 20%。
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引用次数: 0
Electronic Polarization Leads to a Drier Dewetted State for Hydrophobic Gating in the Big Potassium Channel. 电子极化导致大钾通道疏水门控的干湿状态
IF 4.8 2区 化学 Q2 CHEMISTRY, PHYSICAL Pub Date : 2024-07-15 DOI: 10.1021/acs.jpclett.4c01359
Jiahua Deng, Qiang Cui

In the hydrophobic gating mechanism proposed for some ion channels, ion permeation is not blocked by the physical dimension of the channel pore but by its dewetted state which constitutes the energetic bottleneck. A major source of uncertainty in the mechanism is that the dewetted state was not observed in experiments and only probed in simulations using nonpolarizable force fields, which do not accurately represent the properties of confined water. Here we analyze hydration of the central cavity in the pore-gate domain of the Big Potassium channel using molecular dynamics and grand canonical Monte Carlo simulations with enhanced sampling techniques. Including polarization leads to a much drier dewetted state and a higher barrier for the transition to the wet state, suggesting more effective hydrophobic gating. The simulations also identify two backbone carbonyls at the bottom of the selectivity filter as good candidates for characterizing the dewetted state using infrared spectroscopies.

在针对某些离子通道提出的疏水门控机制中,离子渗透不受通道孔隙物理尺寸的阻碍,而是受其露湿状态的阻碍,而露湿状态构成了能量瓶颈。该机制的一个主要不确定因素是实验中没有观察到露湿状态,只能通过使用非极化力场进行模拟探测,而非极化力场并不能准确代表封闭水的特性。在这里,我们利用分子动力学和大规范蒙特卡洛模拟以及增强采样技术分析了大钾通道孔-栅域中央空腔的水合作用。包括极化在内的水合作用会导致更干燥的脱湿态和更高的湿态转换障碍,这表明疏水门控更为有效。模拟还确定了选择性过滤器底部的两个骨架羰基,它们是利用红外光谱分析露湿状态特征的良好候选物。
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引用次数: 0
Modeling Scanning Electrochemical Cell Microscopy (SECCM) in Twisted Bilayer Graphene. 在扭曲双层石墨烯中模拟扫描电化学电池显微镜 (SECCM)。
IF 4.8 2区 化学 Q2 CHEMISTRY, PHYSICAL Pub Date : 2024-07-12 DOI: 10.1021/acs.jpclett.4c01002
Mohammad Babar, Venkatasubramanian Viswanathan

Twisted 2D-flat band materials host exotic quantum phenomena and novel moiré patterns, showing immense promise for advanced spintronic and quantum applications. Here, we evaluate the nanostructure-activity relationship in twisted bilayer graphene by modeling it under the scanning electrochemical cell microscopy setup to resolve its spatial moiré domains. We solve the steady state ion transport inside a 3D nanopipette to isolate the current response at AA and AB domains. Interfacial reaction rates are obtained from a modified Marcus-Hush-Chidsey theory combining input from a tight binding model that describes the electronic structure of bilayer graphene. High rates of redox exchange are observed at the AA domains, an effect that reduces with diminished flat bands or a larger cross-sectional area of the nanopipette. Using voltammograms, we identify an optimal voltage that maximizes the current difference between the domains. Our study lays down the framework to electrochemically capture prominent features of the band structure that arise from spatial domains and deformations in 2D flat-band materials.

扭曲的二维平带材料承载着奇异的量子现象和新颖的摩尔纹,为先进的自旋电子和量子应用带来了巨大的前景。在这里,我们通过在扫描电化学细胞显微镜设置下对扭曲双层石墨烯进行建模,以解析其空间摩尔纹域,从而评估扭曲双层石墨烯的纳米结构与活性之间的关系。我们求解了三维纳米吸管内的稳态离子传输,从而分离出 AA 和 AB 域的电流响应。界面反应速率由修改后的 Marcus-Hush-Chidsey 理论获得,该理论结合了描述双层石墨烯电子结构的紧密结合模型的输入。在 AA 结构域观察到了较高的氧化还原反应速率,这种效应随着平带的减小或纳米吸头横截面积的增大而减弱。通过伏安图,我们确定了一个最佳电压,该电压可最大限度地增加畴之间的电流差。我们的研究为电化学捕捉二维平带材料中空间畴和变形所产生的带状结构的突出特征奠定了基础。
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引用次数: 0
Spectrally Stable and Bright Red Perovskite Light-Emitting Diodes. 光谱稳定、亮度高的红色 Perovskite 发光二极管。
IF 4.8 2区 化学 Q2 CHEMISTRY, PHYSICAL Pub Date : 2024-07-12 DOI: 10.1021/acs.jpclett.4c01757
Fuyi Zhou, Chang Yi, Jianhong Wu, You Ke, Yuyang Zhang, Nana Wang, Jianpu Wang

Mixing iodide and bromide in three-dimensional metal-halide perovskites is a facile strategy for achieving red light-emitting diodes (LEDs). However, these devices often face challenges such as instability in electroluminescence spectra and low brightness due to phase segregation in mixed-halide perovskites. Here, we demonstrate spectrally stable and bright red perovskite LEDs by substituting some of the halide ions with pseudohalogen thiocyanate ions (SCN-). We find that SCN- can occupy halogen vacancies, thereby releasing microstrain and passivating defects in the perovskite crystals. This leads to the suppression of mixed-halide phase segregation under electrical bias. As a result, the red perovskite LEDs exhibit a high brightness of >35 000 cd m-2 with stable Commission Internationale de l'Eclairage (CIE) coordinates of (0.713, 0.282). This brightness surpasses that of the best-performing red perovskite LEDs, showing great promise for advancing perovskite LEDs in display and lighting applications.

在三维金属卤化物包晶石中混合碘化物和溴化物是实现红色发光二极管(LED)的一种简便策略。然而,这些器件往往面临着一些挑战,例如电致发光光谱的不稳定性以及混合卤化物包晶中的相分离导致的低亮度。在这里,我们通过用假卤素硫氰酸根离子(SCN-)取代部分卤素离子,展示了光谱稳定、亮度高的红色包晶发光二极管。我们发现,SCN- 可以占据卤素空位,从而释放微应变并钝化包晶中的缺陷。这就抑制了电偏压下的混合卤化物相分离。因此,红色透辉石 LED 显示出大于 35 000 cd m-2 的高亮度,国际照明委员会(CIE)坐标稳定在 (0.713, 0.282)。这一亮度超过了性能最好的红色包晶发光二极管,为推动包晶发光二极管在显示和照明领域的应用带来了巨大希望。
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引用次数: 0
Nonadiabatic Tunneling in Chemical Reactions. 化学反应中的非绝热隧道效应
IF 4.8 2区 化学 Q2 CHEMISTRY, PHYSICAL Pub Date : 2024-07-12 DOI: 10.1021/acs.jpclett.4c01098
Jeremy O Richardson

Quantum tunneling can have a dramatic effect on chemical reaction rates. In nonadiabatic reactions such as electron transfers or spin crossovers, nuclear tunneling effects can be even stronger than for adiabatic proton transfers. Ring-polymer instanton theory enables molecular simulations of tunneling in full dimensionality and has been shown to be far more reliable than commonly used separable approximations. First-principles instanton calculations predict significant nonadiabatic tunneling of heavy atoms even at room temperature and give excellent agreement with experimental measurements for the intersystem crossing of two nitrenes in cryogenic matrix isolation, the spin-forbidden relaxation of photoexcited thiophosgene in the gas phase, and singlet oxygen deactivation in water at ambient conditions. Finally, an outlook of further theoretical developments is discussed.

量子隧道效应会对化学反应速率产生巨大影响。在非绝热反应(如电子转移或自旋交叉)中,核隧道效应甚至比绝热质子转移更强。环聚物瞬子理论能够在全维度上对隧穿进行分子模拟,并已被证明比常用的可分离近似方法可靠得多。第一原理瞬子计算预测了即使在室温下重原子也会发生显著的非绝热隧穿,并与低温基质隔离中两个硝基苯醚的系统间穿越、气相中光激发硫代磷炔的自旋禁止弛豫以及环境条件下水中单线态氧的失活等实验测量结果非常吻合。最后,讨论了进一步理论发展的前景。
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引用次数: 0
Electronic Structure of Biexcitons in Metal Halide Perovskite Nanoplatelets. 金属卤化物过氧化物纳米小板中的双激子电子结构。
IF 4.8 2区 化学 Q2 CHEMISTRY, PHYSICAL Pub Date : 2024-07-12 DOI: 10.1021/acs.jpclett.4c01719
Juan I Climente, José L Movilla, Josep Planelles

A theoretical description of biexcitons in metal halide perovskite nanoplatelets is presented. The description is based on a variational effective mass model, including polaronic effects by means of a Haken potential. The strong quantum and dielectric confinements are shown to squeeze the biexciton under the polaronic radius, which greatly enhances Coulomb attractions and (to a lesser extent) repulsions. This explains the need for effective dielectric constants approaching the high-frequency limit in previous simulations, and the binding energies exceeding 40 meV observed in single-monolayer nanoplatelets. Biexcitons are formed by a pair of weakly interacting excitons, with a roughly rectangular geometry. This translates into a constant ratio between biexciton and exciton binding energies (2D Haynes rule) well below the ideal value of ΔBXX = 0.228 proposed for squared biexcitons. The ratio is independent of the number of monolayers in the platelet, but it does depend on the lateral and dielectric confinement.

本文从理论上描述了金属卤化物过氧化物纳米片中的双激子。该描述基于变分有效质量模型,通过哈肯电势将极子效应包括在内。研究表明,强量子约束和介电约束会将双激子挤压到极性半径之下,从而大大增强库仑吸引力和(在较小程度上)排斥力。这就解释了为什么在以前的模拟中需要接近高频极限的有效介电常数,以及在单层纳米平板中观察到的超过 40 meV 的结合能。双激子由一对弱相互作用的激子形成,几何形状大致呈矩形。这意味着双电子和激子结合能(二维海恩斯规则)之间的比值恒定,远低于为正方形双电子提出的理想值 ΔBX/ΔX = 0.228。该比率与平板中单层的数量无关,但与横向约束和介电约束有关。
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引用次数: 0
Conformation-Selective Ultraviolet–Ultraviolet Hole Burning Spectra of Ubiquitin Ions in a Cryogenic Ion Trap 低温离子阱中泛素离子的构象选择性紫外-紫外孔燃烧光谱
IF 6.475 2区 化学 Q2 CHEMISTRY, PHYSICAL Pub Date : 2024-07-12 DOI: 10.1021/acs.jpclett.4c01385
Il Tae Yoo, Jinho Jeong, Han Jun Eun, Jiyeon Yun, Jiyoung Heo, Nam Joon Kim
Understanding the structural variations of conformational isomers in proteins is crucial for elucidating protein folding mechanisms. Here, we present a novel method for obtaining conformation-selective ultraviolet (UV)–UV hole burning (HB) spectra of ubiquitin ions ((Ubi+zH)+z, z = 7–10) produced via electrospray ionization. Our approach involves binding multiple N2 molecules to ubiquitin ions ((Ubi+zH)+z(N2)m, m = 1–55) within a cryogenic ion trap. Upon exposure to UV irradiation, efficient fragmentation of (Ubi+zH)+z(N2)m occurs, primarily yielding bare (Ubi+zH)+z ions as fragments. The significant mass difference between the parent and fragment ions facilitates the acquisition of UV–UV HB spectra, which reveal the presence of at least two distinct conformers. Molecular dynamics simulations suggest that these conformers correspond to A-state structures, differing only in the interactions of a tyrosine residue with neighboring residues. Our findings underscore UV–UV HB spectroscopy of protein ions as a powerful tool for exploring diverse protein isomers.
了解蛋白质中构象异构体的结构变化对于阐明蛋白质折叠机制至关重要。在这里,我们提出了一种新方法,用于获得通过电喷雾电离产生的泛素离子((Ubi+zH)+z,z = 7-10)的构象选择性紫外(UV)-紫外灼孔(HB)光谱。我们的方法是在低温离子阱中将多个 N2 分子与泛素离子((Ubi+zH)+z(N2)m,m = 1-55)结合。在紫外线照射下,(Ubi+zH)+z(N2)m 会发生高效碎裂,主要产生裸(Ubi+zH)+z 离子碎片。母离子和碎片离子之间的显著质量差异有助于获得紫外-紫外 HB 光谱,该光谱显示至少存在两种不同的构象。分子动力学模拟表明,这些构象与 A 状态结构相对应,仅在酪氨酸残基与邻近残基的相互作用上存在差异。我们的发现强调了蛋白质离子的紫外-紫外 HB 光谱是探索不同蛋白质异构体的有力工具。
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引用次数: 0
A Multipronged Bioengineering, Spectroscopic and Theoretical Approach in Unravelling the Excited-State Dynamics of the Archetype Mycosporine Amino Acid 多管齐下的生物工程、光谱和理论方法揭示原型霉菌素氨基酸的激发态动力学
IF 6.475 2区 化学 Q2 CHEMISTRY, PHYSICAL Pub Date : 2024-07-12 DOI: 10.1021/acs.jpclett.4c01254
Michael Hymas, Sopida Wongwas, Simin Roshan, Abigail L. Whittock, Christophe Corre, Reza Omidyan, Vasilios G. Stavros
Mycosporine glycine (MyG) was produced by the fermentation of a purposely engineered bacterial strain and isolated from this sustainable source. The ultrafast spectroscopy of MyG was then investigated in its native, zwitterionic form (MyGzwitter), via femtosecond transient electronic absorption spectroscopy. Complementary nonadiabatic (NAD) simulations suggest that, upon photoexcitation to the lowest excited singlet state (S1), MyGzwitter undergoes efficient nonradiative decay to repopulate the electronic ground state (S0). We propose an initial ultrafast ring-twisting mechanism toward an S1/S0 conical intersection, followed by internal conversion to S0 and subsequent vibrational cooling. This study illuminates the workings of the archetype mycosporine, providing photoprotection, in the UV–B range, to organisms such as corals, macroalgae, and cyanobacteria. This study also contributes to our growing understanding of the photoprotection mechanisms of life.
霉菌素甘氨酸(MyG)由特意设计的细菌菌株发酵产生,并从这一可持续来源中分离出来。然后通过飞秒瞬态电子吸收光谱研究了 MyG 的原生齐聚物形式(MyGzwitter)的超快光谱。互补非绝热(NAD)模拟表明,在光激发到最低激发单线态(S1)时,MyGzwitter 会发生有效的非辐射衰变,以重新填充电子基态(S0)。我们提出了一种走向 S1/S0 锥形交点的初始超快环扭转机制,随后内部转化为 S0 并随之振动冷却。这项研究揭示了原型霉菌素的工作原理,它在紫外线-B 范围内为珊瑚、大型藻类和蓝藻等生物提供光保护。这项研究还有助于加深我们对生命光保护机制的理解。
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引用次数: 0
Wide-Dynamic-Range Control of Quantum-Electrodynamic Electron Transfer Reactions in the Weak Coupling Regime 弱耦合状态下量子电动电子转移反应的宽动态范围控制
IF 6.475 2区 化学 Q2 CHEMISTRY, PHYSICAL Pub Date : 2024-07-12 DOI: 10.1021/acs.jpclett.4c01265
Yu-Chen Wei, Liang-Yan Hsu
Catalyzing reactions effectively by vacuum fluctuations of electromagnetic fields is a significant challenge within the realm of chemistry. As opposed to most studies based on vibrational strong coupling, we introduce an innovative catalytic mechanism driven by weakly coupled polaritonic fields. Through the amalgamation of macroscopic quantum electrodynamics (QED) principles with Marcus electron transfer (ET) theory, we predict that ET reaction rates can be precisely modulated across a wide dynamic range by controlling the size and structure of nanocavities. Compared to QED-driven radiative ET rates in free space, plasmonic cavities induce substantial rate enhancements spanning the range from 103- to 10-fold. By contrast, Fabry–Perot cavities engender rate suppression spanning the range from 10–2- to 10–1-fold. This work overcomes the necessity of using strong light–matter interactions in QED chemistry, opening up a new era of manipulating QED-based chemical reactions in a wide dynamic range.
利用真空电磁场波动有效催化反应是化学领域的一项重大挑战。与大多数基于振动强耦合的研究不同,我们引入了一种由弱耦合极性场驱动的创新催化机制。通过将宏观量子电动力学(QED)原理与马库斯电子转移(ET)理论相结合,我们预测通过控制纳米腔体的尺寸和结构,可以在宽动态范围内精确调节 ET 反应速率。与自由空间中由 QED 驱动的辐射 ET 速率相比,等离子体空腔诱导的速率大幅提高,范围从 103 倍到 10 倍不等。相比之下,法布里-珀罗空腔则会产生速率抑制,范围从 10-2 倍到 10-1 倍不等。这项工作克服了在 QED 化学中使用强光-物质相互作用的必要性,开辟了在宽动态范围内操纵基于 QED 的化学反应的新纪元。
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引用次数: 0
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The Journal of Physical Chemistry Letters
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