The Journal of Physical Chemistry A最新文献

{"title":"Overview on Building Blocks and Applications of Efficient and Robust Extended Tight Binding.","authors":"Abylay Katbashev, Marcel Stahn, Thomas Rose, Vahideh Alizadeh, Marvin Friede, Christoph Plett, Pit Steinbach, Sebastian Ehlert","doi":"10.1021/acs.jpca.4c08263","DOIUrl":"https://doi.org/10.1021/acs.jpca.4c08263","url":null,"abstract":"<p><p>The extended tight binding (xTB) family of methods opened many new possibilities in the field of computational chemistry. Within just 5 years, the GFN2-xTB parametrization for all elements up to <i>Z</i> = 86 enabled more than a thousand applications, which were previously not feasible with other electronic structure methods. The xTB methods provide a robust and efficient way to apply quantum mechanics-based approaches for obtaining molecular geometries, computing free energy corrections or describing noncovalent interactions and found applicability for many more targets. A crucial contribution to the success of the xTB methods is the availability within many simulation packages and frameworks, supported by the open source development of its program library and packages. We present a comprehensive summary of the applications and capabilities of xTB methods in different fields of chemistry. Moreover, we consider the main software packages for xTB calculations, covering their current ecosystem, novel features, and usage by the scientific community.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143514123","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":"Highly Symmetrical Palladium Cluster Complexes with Either Anticuboctahedral or Cuboctahedral Pd₁₃ Core: Theoretical Insight into Factors Determining Symmetrical Structure.","authors":"Yu Tian, Bo Zhu, Tetsuro Murahashi, Shigeyoshi Sakaki","doi":"10.1021/acs.jpca.4c07401","DOIUrl":"https://doi.org/10.1021/acs.jpca.4c07401","url":null,"abstract":"&lt;p&gt;&lt;p&gt;One of the important open questions is what factor(s) determines the symmetry of the structure of the metal nanocluster complex. [Pd&lt;sub&gt;13&lt;/sub&gt;(μ-Cl)&lt;sub&gt;3&lt;/sub&gt;(μ&lt;sub&gt;4&lt;/sub&gt;-C&lt;sub&gt;16&lt;/sub&gt;H&lt;sub&gt;16&lt;/sub&gt;)&lt;sub&gt;6&lt;/sub&gt;]&lt;sup&gt;+&lt;/sup&gt; (&lt;b&gt;Anti-μ&lt;/b&gt;&lt;sub&gt;&lt;b&gt;4&lt;/b&gt;&lt;/sub&gt;; C&lt;sub&gt;16&lt;/sub&gt;H&lt;sub&gt;16&lt;/sub&gt; = [2.2]paracyclophane) has an anticuboctahedral Pd&lt;sub&gt;13&lt;/sub&gt; core unlike [Pd&lt;sub&gt;13&lt;/sub&gt;(μ&lt;sub&gt;4&lt;/sub&gt;-C&lt;sub&gt;7&lt;/sub&gt;H&lt;sub&gt;7&lt;/sub&gt;)&lt;sub&gt;6&lt;/sub&gt;]&lt;sup&gt;2+&lt;/sup&gt; with cuboctahedral Pd&lt;sub&gt;13&lt;/sub&gt; core. DFT calculations show that &lt;b&gt;Anti-μ&lt;/b&gt;&lt;sub&gt;&lt;b&gt;4&lt;/b&gt;&lt;/sub&gt; is more stable than isomers, [Pd&lt;sub&gt;13&lt;/sub&gt;(μ-Cl)&lt;sub&gt;3&lt;/sub&gt;(μ&lt;sub&gt;3&lt;/sub&gt;-C&lt;sub&gt;16&lt;/sub&gt;H&lt;sub&gt;16&lt;/sub&gt;)&lt;sub&gt;3&lt;/sub&gt;(μ&lt;sub&gt;4&lt;/sub&gt;-C&lt;sub&gt;16&lt;/sub&gt;H&lt;sub&gt;16&lt;/sub&gt;)&lt;sub&gt;3&lt;/sub&gt;]&lt;sup&gt;+&lt;/sup&gt; and [Pd&lt;sub&gt;13&lt;/sub&gt;(μ-Cl)&lt;sub&gt;3&lt;/sub&gt;(μ&lt;sub&gt;2&lt;/sub&gt;-C&lt;sub&gt;16&lt;/sub&gt;H&lt;sub&gt;16&lt;/sub&gt;)&lt;sub&gt;3&lt;/sub&gt;(μ&lt;sub&gt;4&lt;/sub&gt;-C&lt;sub&gt;16&lt;/sub&gt;H&lt;sub&gt;16&lt;/sub&gt;)&lt;sub&gt;3&lt;/sub&gt;]&lt;sup&gt;+&lt;/sup&gt; with cuboctahedral Pd&lt;sub&gt;13&lt;/sub&gt; core (&lt;b&gt;Cubo-μ&lt;/b&gt;&lt;sub&gt;&lt;b&gt;3&lt;/b&gt;&lt;/sub&gt;&lt;b&gt;,μ&lt;/b&gt;&lt;sub&gt;&lt;b&gt;4&lt;/b&gt;&lt;/sub&gt; and &lt;b&gt;Cubo-μ&lt;/b&gt;&lt;sub&gt;&lt;b&gt;2&lt;/b&gt;&lt;/sub&gt;&lt;b&gt;,μ&lt;/b&gt;&lt;sub&gt;&lt;b&gt;4&lt;/b&gt;&lt;/sub&gt;, respectively) and [Pd&lt;sub&gt;13&lt;/sub&gt;(μ-Cl)&lt;sub&gt;3&lt;/sub&gt;(μ&lt;sub&gt;3&lt;/sub&gt;-C&lt;sub&gt;16&lt;/sub&gt;H&lt;sub&gt;16&lt;/sub&gt;)&lt;sub&gt;6&lt;/sub&gt;]&lt;sup&gt;+&lt;/sup&gt; with distorted icosahedral Pd&lt;sub&gt;13&lt;/sub&gt; core (&lt;b&gt;dis-Ih-μ&lt;/b&gt;&lt;sub&gt;&lt;b&gt;3&lt;/b&gt;&lt;/sub&gt;). Not the stabilities of [Pd&lt;sub&gt;13&lt;/sub&gt;(μ-Cl)&lt;sub&gt;3&lt;/sub&gt;]&lt;sup&gt;+&lt;/sup&gt; core and (C&lt;sub&gt;16&lt;/sub&gt;H&lt;sub&gt;16&lt;/sub&gt;)&lt;sub&gt;6&lt;/sub&gt; ligand-shell but rather the interaction energy (&lt;i&gt;E&lt;/i&gt;&lt;sub&gt;int&lt;/sub&gt;) between [Pd&lt;sub&gt;13&lt;/sub&gt;(μ-Cl)&lt;sub&gt;3&lt;/sub&gt;]&lt;sup&gt;+&lt;/sup&gt; and (C&lt;sub&gt;16&lt;/sub&gt;H&lt;sub&gt;16&lt;/sub&gt;)&lt;sub&gt;6&lt;/sub&gt; ligand-shell determines stabilities of these complexes. μ&lt;sub&gt;4&lt;/sub&gt;-C&lt;sub&gt;16&lt;/sub&gt;H&lt;sub&gt;16&lt;/sub&gt; coordination bond is stronger than μ&lt;sub&gt;2&lt;/sub&gt;- and μ&lt;sub&gt;3&lt;/sub&gt;-coordination bonds, leading to a larger &lt;i&gt;E&lt;/i&gt;&lt;sub&gt;int&lt;/sub&gt; value in &lt;b&gt;Anti-μ&lt;/b&gt;&lt;sub&gt;&lt;b&gt;4&lt;/b&gt;&lt;/sub&gt; than in isomers bearing μ&lt;sub&gt;2&lt;/sub&gt;- or μ&lt;sub&gt;3&lt;/sub&gt;-coordination bond. An icosahedral Pd&lt;sub&gt;13&lt;/sub&gt; core is not favorable for these Pd&lt;sub&gt;13&lt;/sub&gt; complexes because of the absence of a Pd&lt;sub&gt;4&lt;/sub&gt; plane. [Pd&lt;sub&gt;13&lt;/sub&gt;(μ-Cl)&lt;sub&gt;3&lt;/sub&gt;(μ&lt;sub&gt;4&lt;/sub&gt;-C&lt;sub&gt;16&lt;/sub&gt;H&lt;sub&gt;16&lt;/sub&gt;)&lt;sub&gt;6&lt;/sub&gt;]&lt;sup&gt;+&lt;/sup&gt; with cuboctahedral Pd&lt;sub&gt;13&lt;/sub&gt; (&lt;b&gt;Cubo-μ&lt;/b&gt;&lt;sub&gt;&lt;b&gt;4&lt;/b&gt;&lt;/sub&gt;) is not stable despite the presence of six Pd&lt;sub&gt;4&lt;/sub&gt; planes, because its three Pd&lt;sub&gt;4&lt;/sub&gt; planes with μ-Cl ligand cannot form μ&lt;sub&gt;4&lt;/sub&gt;-C&lt;sub&gt;16&lt;/sub&gt;H&lt;sub&gt;16&lt;/sub&gt; coordination bond due to steric repulsion of C&lt;sub&gt;16&lt;/sub&gt;H&lt;sub&gt;16&lt;/sub&gt; with the μ-Cl ligand. In contrast, &lt;b&gt;Anti-μ&lt;/b&gt;&lt;sub&gt;&lt;b&gt;4&lt;/b&gt;&lt;/sub&gt; is stable because it has six Pd&lt;sub&gt;4&lt;/sub&gt; planes with no Cl ligand to form strong μ&lt;sub&gt;4&lt;/sub&gt;-C&lt;sub&gt;16&lt;/sub&gt;H&lt;sub&gt;16&lt;/sub&gt; coordination bonds without steric repulsion. Also, discussion is presented on the difference in symmetry between [Pd&lt;sub&gt;13&lt;/sub&gt;(μ-Cl)&lt;sub&gt;3&lt;/sub&gt;(μ&lt;sub&gt;4&lt;/sub&gt;-C&lt;sub&gt;16&lt;/sub&gt;H&lt;sub&gt;16&lt;/sub&gt;)&lt;sub&gt;6&lt;/sub&gt;]&lt;sup&gt;+&lt;/sup&gt; and [Pd&lt;sub&gt;13&lt;/sub&gt;(μ&lt;sub&gt;4&lt;/sub&gt;-C&lt;sub&gt;7&lt;/sub&gt;H&lt;sub&gt;7&lt;/sub&gt;)&lt;sub&gt;6&lt;/sub&gt;]&lt;sup&gt;2+&lt;/s","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143514057","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":"Ab Initio Molecular Dynamics Simulation Study on the Thermal Decomposition Mechanism of Two F-Containing Compounds: 3,3,7,7-Tetrakis(difluoramino)-octahydro-1,5-dinitro-1,5-diazocine (HNFX) and 1,3,5-Trinitro-2,2-bis(trifluoromethyl)-1,3,5-triazinane (TNBFT).","authors":"Kai Zhong, Chaoyang Zhang","doi":"10.1021/acs.jpca.5c00215","DOIUrl":"https://doi.org/10.1021/acs.jpca.5c00215","url":null,"abstract":"<p><p>F-containing explosives with additional F atoms compared to traditional CHON ones should contain a more complex decomposition mechanism. Nevertheless, understanding the mechanism and effect of F-containing groups on stability remains limited. This study investigates the thermal decomposition mechanisms of two typical F-containing compounds, 3,3,7,7-tetrakis(difluoramino)-octahydro-1,5-dinitro-1,5-diazocine (HNFX) and 1,3,5-trinitro-2,2-bis(trifluoromethyl)-1,3,5-triazinane (TNBFT), using ground-state ab initio molecular dynamics simulations and compares them with RDX. The results show that HNFX decomposes from the partition of -NF₂ to form NF₃ and HF at 1500 K and above 2000 K, respectively, while TNBFT undergoes the concerted H transfer and HONO elimination at 1500 K and the N-NO₂ bond cleavage at relatively high temperatures. Additionally, HF and fluorocarbons, as the primary fluorinated products, lower the yields of H₂O and CO₂ compared to RDX, but they can act as oxidizers in combustion with Al particles. Moreover, it is found that F-containing groups significantly weaken the bonds nearby and the total molecular stability. Based on our bond strength analysis and simulation results, the reported experimental confirmation of the thermal stability of HNFX may be questionable. This insight is expected to deepen the thermal decomposition mechanisms of F-containing explosives and guide the design of high-performance composites thereof.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143514052","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":"Quantum Chemical Calculations of the Nonenzymatic Bicarbonate Ion-Catalyzed Lactamization of Ornithine Residues to Identify the Components of Primitive Proteins.","authors":"Ayato Mizuno, Tomoki Nakayoshi, Eiji Kurimoto, Koichi Kato, Akifumi Oda","doi":"10.1021/acs.jpca.4c07299","DOIUrl":"https://doi.org/10.1021/acs.jpca.4c07299","url":null,"abstract":"<p><p>Ornithine (Orn) is biochemically significant amino acid and has a structure similar to lysine, yet a noncanonical amino acid. When Orn is incorporated into a peptide chain, irreversible nonenzymatic C-terminal peptide cleavage and lactamization occur, inhibiting the synthesis of a peptide chain. The Orn reactivity is high, and likely to proceed even in the absence of enzymes. Nonenzymatic reactions could proceed with prebiotic catalysts that existed on the primitive Earth and may have played a crucial role in the origin of proteins. However, the mechanisms of these reactions have not been studied in great detail. In this study, quantum chemical calculations of these reactions were performed using the model compound Ac-Orn-NMe (Ac = acetyl, NMe = methylamino). Two reaction stages were considered: cyclization and C-terminal cleavage. Because the <i>gem</i>-hydroxylamine intermediate structure is diastereomeric, reaction pathways involving both R- and S-configured intermediates were investigated. The activation barriers for the Orn lactamization involving R- and S-intermediates with bicarbonate ions as a catalyst were estimated to be 82.4 and 76.6 kJ mol^-1, respectively. Thus, the Orn lactamization can proceed easily compared to lysine. The high reactivity of Orn may be the reason for the exclusion of Orn from the Magic 20.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143497525","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":"Infrared Spectroscopy of Radical Cation Clusters (NH₃)₂⁺ and (NH₃)₃<sup />.","authors":"Amandeep Singh, Arisa Iguchi, Tom C Bernaards, Zane Golpariani, Kenta Mizuse, Asuka Fujii, Hajime Tanuma, Toshiyuki Azuma, Susumu Kuma, Andrey Vilesov","doi":"10.1021/acs.jpca.4c08362","DOIUrl":"https://doi.org/10.1021/acs.jpca.4c08362","url":null,"abstract":"<p><p>The ionization of protic molecules such as H₂O and NH₃ in the condensed phase initiates ion-molecule reactions, which remain poorly understood. Studies of the structure and reactivity of small ionic clusters in molecular beams have yielded a wealth of information on protonated clusters. However, unprotonated radical cation clusters have a low concentration in a typical experiment and thus remain challenging. Here we report the infrared spectra of the (NH₃)₂⁺ and (NH₃)₃⁺ radical cations solvated in helium nanodroplets. Radical cation clusters often have several isomers with different ionic cores, including proton-transferred and hemibonded structures. Infrared spectra of the cations obtained in this work indicate that the formation of the ammonia dimer ((NH₃)₂⁺) and trimer ((NH₃)₃⁺) cations yields the proton-transferred structures, which correspond to the respective global minima of the calculated structures. Spectral assignments are corroborated by density functional theory calculations. The spectra also indicate that the NH₄⁺ and NH₃ moieties within the clusters undergo internal rotation with rotational constants close to those in the gas phase.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143514076","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":"Developing Red and Near-Infrared Delayed Fluorescence Emission in Nitrogen-Substituted Donor-Acceptor Polycyclic Hydrocarbon OLED Emitters: A Theoretical Study.","authors":"Smruti Ranjan Sahoo, Glib V Baryshnikov, Hans Ågren","doi":"10.1021/acs.jpca.4c07345","DOIUrl":"https://doi.org/10.1021/acs.jpca.4c07345","url":null,"abstract":"<p><p>Nitrogen substitutions have shown a great impact for the development of thermally activated delayed fluorescence (TADF)-based organic light-emitting diode (OLED) materials. In particular, much focus has been devoted to nitrogen-substituted polycyclic aromatic hydrocarbons (PAHs) for TADF emitters. In this context, we provide here a molecular design approach for symmetric nitrogen substitutions in fused benzene ring PAHs based on the dibenzo[<i>a</i>,<i>c</i>]picene (DBP) molecule. We designed possible donor-acceptor (D-A) compounds with dimethylcarbazole (DMCz) and dimethyldiphenylamine (DMDPA) donors and studied the structure and photophysics of the designed D-A compounds. The twisted and extended D-A-type PAH emitters demonstrate red and near-infrared (NIR) TADF emission. Nitrogen substitutions lead to significant LUMO stabilization and reduced HOMO-LUMO energy gaps as well. Additionally, we computed significantly smaller singlet-triplet energy splittings (Δ<i>E</i>_ST) in comparison to non-nitrogen-substituted compounds. The investigated <i>ortho</i>-linked D-A compounds show relatively large donor-acceptor twisting separation and small Δ<i>E</i>_ST compared to their <i>para</i>-linked counterparts. For higher number nitrogen (4N)-substituted emitters, we predict small adiabatic Δ<i>E</i>_ST (Δ<i>E</i>_ST^adia) in the range 0.01-0.13 eV, and with the <i>tert</i>-butylated donors, we even obtained Δ<i>E</i>_ST^adia values as small as 0.007 eV. Computed spin-orbit coupling (SOC) for the T₁ triplet state on the order of 0.12-2.28 cm^-1 suggests significant repopulation of singlet charge transfer (¹CT) excitons from the triplet CT and locally excited (³CT+LE) states. Importantly, the small Δ<i>E</i>_ST^adia and large SOC values induce a reverse intersystem crossing (RISC) rate as high as 1 × 10⁶ s^-1, which will cause red and NIR delayed fluorescence in the 4N-substituted D-A emitters. Notably, we predict red TADF emission for the <i>para</i>-linked compound <b>B4</b> at 670 nm and the <i>ortho</i>-linked compound <b>D4</b> at 713 nm and delayed NIR emission at 987 and 1217 nm for the <i>ortho</i>-linked compounds <b>D3</b> and <b>E3</b>, respectively.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143497560","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":"Acidity Prediction in Arbitrary Solvents: Machine Learning Based on Semiempirical Molecular Orbital Calculation.","authors":"Rima Suzuki, Hirotoshi Mori","doi":"10.1021/acs.jpca.4c07367","DOIUrl":"https://doi.org/10.1021/acs.jpca.4c07367","url":null,"abstract":"<p><p>Due to the nonlinearity of solvent effects, careful solvent selection is essential when using acids in different applications. However, there is a lack of measurements of p<i>K</i>_a while systematically changing molecular structures and solvents. Consequently, there was no protocol to predict the acidity in arbitrary environments. This study developed an arbitrary environment p<i>K</i>_a prediction protocol by integrating quantum chemical calculations using a polarizable continuum model and machine learning. This protocol constructed models to predict the acidity of biologically relevant molecules in water and candidate superstrong acids in organic solvents. For both systems, the p<i>K</i>_a can be predicted with an average absolute error of 1.1 by learning relatively small number of data. This approach can also account for the nonlinear decay of acidity with solvation in different environments (compression effect). The versatility of the protocol extends to its applicability to a wide range of compounds, including those with complex electronic state changes upon proton dissociation, supporting research in diverse fields including, but not limited to, drug discovery and engineering.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143497558","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":"Observation of a New TICT State during the Photophysical Process of an Al³⁺ Sensor.","authors":"Bingqing Sun, Lei Liu, Juyoung Yoon","doi":"10.1021/acs.jpca.4c07483","DOIUrl":"https://doi.org/10.1021/acs.jpca.4c07483","url":null,"abstract":"<p><p>Schiff base with a C═N bond is widely used in the fabrication of turn-on sensors for cations. The isomerization of C═N is generally believed to induce a dark state and quenches the sensor's fluorescence. With the aid of time-dependent density functional theory (TDDFT), this contribution performs a comprehensive investigation on the photophysical process of a turn-on sensor for Al³⁺. The isomerization of C═N leads to a non-emissive twisted intramolecular charge transfer (TICT) state, which is initiated by an early stage excited state intramolecular proton transfer (ESIPT) process. However, this isomerization process has a very large energy barrier and low reaction rate that cannot effectively quench the sensor's fluorescence. Interestingly, a brand new non-emissive TICT state is observed which is not induced by the isomerization of C═N but by the rotation of a neighboring C-C bond. Due to the low rotation energy barrier, this new TICT state can be attained easily and opens up an effective channel for non-emissive decays. This observation implies that the excited state potential energy surface for sensors based on a Schiff base should be much more complicated than expected. Based on the photophysical process, the sensing mechanism for Al³⁺ as well as its selectivity in the face of interfering cations are uncovered.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143514118","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":"Microscopic Insights into the Catalytic Activity-Stability Trade-Off on Copper Nanoclusters for CO₂ Hydrogenation to HCOOH.","authors":"Zechen Ye, Kuiwei Yang, Kang Hui Lim, Sibudjing Kawi, Jianwen Jiang","doi":"10.1021/acs.jpca.4c08693","DOIUrl":"https://doi.org/10.1021/acs.jpca.4c08693","url":null,"abstract":"<p><p>Lowly coordinated copper clusters are the most cost-effective benchmark catalysts for CO₂ hydrogenation, but there is a meticulous balance between catalytic activity and stability. Herein, density functional theory (DFT) calculations are implemented to examine the catalytic performance of Cu_<i>n</i> nanoclusters (<i>n</i> = 4, 8, 16, 32) in CO₂-to-HCOOH conversion. Facile activation of H₂ is observed with significant electron transfer from Cu_<i>n</i> to antibonding orbitals of H₂; conversely, the C-O bond of CO₂ is poorly activated due to a low degree of orbital overlap. During the reaction, structural fluxionality occurs on Cu₄ and Cu₈ because of the low stability; however, negligible deformation is observed on Cu₁₆ and Cu₃₂. In addition, Cu₁₆ achieves a good balance between the kinetics of each elementary reaction, which is, however, difficult to be maintained on Cu₄, Cu₈, and Cu₃₂. Therefore, Cu₁₆ satisfies the trade-off between activity and stability in CO₂-to-HCOOH conversion. Energy decomposition analysis clarifies that the activation barrier of the second hydrogenation originates from the energy of hydride desorption, the electronic repulsion energy due to hydroxyl group formation, as well as the energy for local Cu-O bond cleavage. The high energy demand on the second hydrogenation is mainly sourced from the last term. From the bottom up, this work provides microscopic insights into the catalytic activity-stability trade-off in CO₂ hydrogenation to HCOOH and would facilitate the rational design of advanced catalysts for the high-value utilization of CO₂ exhaust gas.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143490338","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":"In-Field and Zero-Field Relaxation Dynamics of Dysprosocenium in Solution.","authors":"William J A Blackmore, Sophie C Corner, Peter Evans, Gemma K Gransbury, David P Mills, Nicholas F Chilton","doi":"10.1021/acs.jpca.4c06678","DOIUrl":"https://doi.org/10.1021/acs.jpca.4c06678","url":null,"abstract":"<p><p>Most of the work in expanding the frontiers of single-molecule magnets employs the chemical design of new molecules to increase the size of the effective barrier (<i>U</i>_eff) or the hysteresis temperature (<i>T</i>_H). Here we explore how perturbing the local environment affects magnetic relaxation properties by dissolving [Dy(Cp^ttt)₂][B(C₆F₅)₄] in two different solvents: difluorobenzene (DFB) and dichloromethane (DCM). Surprisingly, we find no significant effects in the phonon-driven Raman-I regime at higher temperatures, but we do observe that the frozen-solution environment increases the rate of quantum tunneling of the magnetization (QTM) due to an increase in the size of the avoided level crossing. We find that there is a drastic decrease in the Raman relaxation rate at low temperatures for the concentrated DCM and polycrystalline samples under the applied magnetic field where the QTM process is quenched, which is attributed to changes in the low-energy phonon spectrum and is not replicated for the other samples.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143497524","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}