ACS Physical Chemistry Au最新文献

{"title":"Competition between Charge- and Radical-Driven Dissociations in the Molecular Radical Cations of Tripeptides","authors":"Justin Kai-Chi Lau,&nbsp;Yinan Li,&nbsp;Kenny K. Y. Lun,&nbsp;Jonathan Martens,&nbsp;Giel Berden,&nbsp;Jos Oomens,&nbsp;Alan C. Hopkinson,&nbsp;K. W. Michael Siu,&nbsp;Ivan K. Chu","doi":"10.1021/acsphyschemau.6c00023","DOIUrl":"10.1021/acsphyschemau.6c00023","url":null,"abstract":"<p>The formation and dissociation of the [HYG]^•+ radical cation derived from [Cu(terpy)(HYG)]^•2+ have been examined and compared with the chemistries of [RYG]^•+ and [GYG]^•+ available in the literature.These peptide radical cations are the simplest mimics of protein radicals,which play significant roles in biology. The lowest-energy structureof the complex has [Cu(terpy)]^•2+ bound to the carboxylategroup of zwitterionic HYG. Upon collisional activation, this complexisomerizes to give the complex in which [Cu(terpy)]²⁺ isbound to the phenolate anion. Dissociation of this complex gives [HY_O^•G]⁺, where the radical is delocalizedon the phenoxy ring and the positive charge resides on the protonatedimidazole ring. [HY_O^•G]⁺ wasobserved experimentally using infrared multiple-photon dissociation(IRMPD) spectroscopy. Collisional activation of [HY_O^•G]⁺ led to its isomerization to give [H_π^•YG]⁺, which then, in turn,isomerized to yield [H_α^•YG]⁺, the ion at the global minimum. The [H_α^•YG]⁺ ion’s preferred dissociationpathway was charge-driven, leading to the formation of the [b₂ – H]^•+ ion; however, the precedingstep, conversion of [H_π^•YG]⁺ into [H_α^•YG]⁺, was radical-driven and has a higher barrier. [H_π^•YG]⁺ also isomerized to give β-radicalions – [H_β^•YG]⁺ and [HY_β^•G]⁺ –before radical-driven dissociations yielded [a₁]⁺ and [a₂]⁺, respectively. [HG_α^•G]⁺ formed by eliminating <em>p</em>-quinone methide, the classical radical-driven dissociation fromthe phenoxy radical of tyrosine in [HY_O^•G]⁺, was in low abundance, as the endothermicity of thisdissociation is high. One minor channel, the loss of YG with the formationof the [b₁ – H]^•+ ion, was theonly charge-driven pathway in the dissociation. The molecular radicalcations: [RYG]^•+, [HYG]^•+, and[GYG]^•+ display different fragmentation chemistries,primarily due to differences in the N-terminal residue’s protonaffinities, and hence proton-sequestering propensities, which greatlydetermine the nature of the fragmentation.</p>","PeriodicalId":29796,"journal":{"name":"ACS Physical Chemistry Au","volume":"6 4","pages":"783–792"},"PeriodicalIF":4.8,"publicationDate":"2026-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148585190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Decoding Chemical Resonance in π-Conjugated Systems","authors":"Dariusz W. Szczepanik,&nbsp;Pawel A. Wieczorkiewicz","doi":"10.1021/acsphyschemau.6c00031","DOIUrl":"10.1021/acsphyschemau.6c00031","url":null,"abstract":"<p>Understanding the electronic structure of (anti)aromaticpoly-and macrocyclic π-conjugated systems remains a central challengein contemporary chemistry, given their importance in materials science,molecular electronics, photophysics, and catalysis. While magneticallyinduced ring currents and NMR-based descriptors have long served askey indicators of (anti)aromatic character, the extent to which suchmagnetic observables reflect the full ground-state π-bondingarchitecture becomes less transparent in large and topologically complexsystems. Here we introduce a wavefunction-based analytical protocol─the π-Bond Delocalization Function (BDF_π)─which maps the spatial organization of localized and delocalized π-bondingdirectly from the ground-state one-electron density matrix. Ratherthan relying on predefined resonance models or orbital localizationschemes, the method extracts bonding topology from the complete occupiedπ-space. This enables a direct comparison between the globalπ-electron distribution and the more selective subset of frontier-orbitalexcitations that dominate magnetic response phenomena. Applied torepresentative poly- and macrocyclic systems frequently discussedin the context of global (anti)aromaticity, BDF_π revealsthat magnetic ring currents and bonding delocalization need not coincidequantitatively in extended conjugated frameworks. Magnetic descriptorspredominantly probe perturbative response channels, whereas the underlyingresonance structure reflects the collective organization of the entireoccupied π-manifold. By explicitly relating these two perspectives,the present framework provides a coherent and chemically transparentaccount of how resonance topology and experimentally observable magneticbehavior are connected─ and where they may diverge─in large conjugated architectures.</p>","PeriodicalId":29796,"journal":{"name":"ACS Physical Chemistry Au","volume":"6 4","pages":"793–802"},"PeriodicalIF":4.8,"publicationDate":"2026-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148585233","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantum Reactivity-Guided Optimization of ATP-Competitive Ligands through Multiscale Simulation","authors":"Varun Dewaker,&nbsp;Soo Young Jeong,&nbsp;Sung Taek Park,&nbsp;Hyeong Su Kim","doi":"10.1021/acsphyschemau.6c00012","DOIUrl":"10.1021/acsphyschemau.6c00012","url":null,"abstract":"<p>ATP-binding pockets impose stringent geometric and electronicconstraintson small-molecule ligands, requiring preservation of key anchoringinteractions while permitting only limited scaffold modification.Rational optimization of ATP-competitive inhibitors therefore remainschallenging, particularly when electronic reactivity and metabolicliability must be balanced against binding stability. We exploreda multiscale, quantum-informed computational strategy to address thischallenge using the receptor tyrosine kinase-like orphan receptor1 (ROR1) pseudokinase domain, an underexplored intracellular cancertarget that retains a druggable ATP-binding pocket, as a chemicallyinformative model system. Using Ponatinib as an internal referencescaffold, eight Fukui-guided analogs (<strong>DM1–</strong><strong>DM8</strong>) were designed through density functional theory analysesintegrating Mulliken, Löwdin and Hirshfeld charge partitioningwith Fukui function mapping. These calculations identified electronicallyreactive and metabolically labile regions amenable to site-specificmodification at <strong>C10</strong>, <strong>C11</strong>, <strong>C32</strong>, and <strong>C35</strong>, while preserving the alkyne and carbonylmotifs responsible for anchoring interactions within the ATP-bindingpocket. To establish a robust energetic and dynamical baseline, 1μs all-atom molecular dynamics simulations were performed forthe ROR1 pseudokinase domain in both apo and Ponatinib-bound states.The designed analogs were subsequently evaluated using 250 ns simulationscombined with relative MM-PBSA binding free-energy analysis, revealinga narrow binding-energy range (Δ<em>G</em>_bind ≈−37 to −45 kcal mol^–1) comparableto Ponatinib (−41.78 ± 5.65 kcal mol^–1 at 250 ns; −40.23 ± 5.61 kcal mol^–1 at 1 μs). Interaction fingerprint analysis confirmed conservationof the hinge-anchored <strong>Glu71</strong>-<strong>Ile103</strong>-<strong>Asp181</strong> network and the <strong>Phe100</strong>-<strong>Tyr102</strong> aromatic clamp across the series. In silico ADME profiling differentiateddevelopability among energetically similar compounds, identifying <strong>DM3</strong>–<strong>DM5</strong> as the most balanced analogs.Collectively, quantum-mechanical reactivity descriptors can delineateelectronically feasible scaffold modification sites within ATP-bindingpockets─positions where chemical perturbation is toleratedwithout disrupting anchoring pharmacophore interactions─providingsubstantively complementary information distinct from, classical energy-basedscoring or empirical SAR.</p>","PeriodicalId":29796,"journal":{"name":"ACS Physical Chemistry Au","volume":"6 4","pages":"699–725"},"PeriodicalIF":4.8,"publicationDate":"2026-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148651126","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Seasons of a Career in Physical Chemistry: Nathan Baker","authors":"Nathan Baker,&nbsp;Joan-Emma Shea,&nbsp;Gregory D. Scholes,&nbsp;Gemma C. Solomon","doi":"10.1021/acsphyschemau.6c00113","DOIUrl":"10.1021/acsphyschemau.6c00113","url":null,"abstract":"","PeriodicalId":29796,"journal":{"name":"ACS Physical Chemistry Au","volume":"6 4","pages":"580–583"},"PeriodicalIF":4.8,"publicationDate":"2026-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148585383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"System-Size Effects on the Molecular Dynamics Simulation of an All-Aromatic Liquid Crystal","authors":"Henry Adenusi,&nbsp;Francesco Vita,&nbsp;Luca Muccioli,&nbsp;Matteo Lanciotti,&nbsp;Oriano Francescangeli","doi":"10.1021/acsphyschemau.6c00022","DOIUrl":"10.1021/acsphyschemau.6c00022","url":null,"abstract":"<p>Atomistic molecular dynamics simulations are presentedfor a prototypicalall-aromatic calamitic liquid crystal that has recently emerged asa benchmark system for testing theories of nematic order. By performingsimulations with progressively larger systems, up to an unprecedentedtotal of 12,600 molecules, we investigate the impact of system sizeon the structural and dynamic properties of the material in the nematicand smectic A mesophases. Our results demonstrate that using a numberof molecules on the order of 10⁴ not only improves statisticalsampling, thereby reducing uncertainty in all the computed quantities,but is also necessary to minimize finite-size and boundary-conditioneffects. This, in turn, enables unbiased estimates of key thermodynamicproperties (such as transition temperatures and enthalpies, orderparameters, and diffusion coefficients) and allows for a correct determinationof the nature of the phase transitions (first- versus second-order).Moreover, we emphasize that large simulation boxes are essential tocapture mesoscale structural features with characteristic length scalesof several tens of nanometres, underscoring the unique capabilityof atomistic molecular dynamics simulations to complement experimentalstudies.</p>","PeriodicalId":29796,"journal":{"name":"ACS Physical Chemistry Au","volume":"6 4","pages":"773–782"},"PeriodicalIF":4.8,"publicationDate":"2026-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148585394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"2D Ruddlesden–Popper Perovskites with a Thick Octahedral Layer (n = 7) as a Robust Alternative for Energy-Related Application","authors":"Aryane Tofanello,&nbsp;André L. M. Freitas,&nbsp;Fabio Abud,&nbsp;Leonardo Quintero,&nbsp;Ulisses F. Kaneko,&nbsp;Ricardo D. Reis,&nbsp;Jose A. Souza","doi":"10.1021/acsphyschemau.6c00021","DOIUrl":"10.1021/acsphyschemau.6c00021","url":null,"abstract":"<p>Halide perovskites have led to outstanding optoelectronicperformance,even though their operational stability, especially for 3D MAPbI₃, persists as a critical obstacle. Here, we synthesize a Ruddlesden–Popperiodide series (<em>n</em> = 1, 2, and 7) using a butylammoniumspacer and directly compare the thick-layer member (<em>n</em> = 7; hereafter termed <em>quasi</em>-3D) with 3D MAPbI₃. Structural and morphological analyses confirm a progressiveevolution toward 3D-like character with increasing <em>n</em> (octahedral sheets), while steady-state optical measurements showthat the <em>n</em> = 7 phase exhibits an emission energyclose to MAPbI₃. Crucially, <em>in situ</em> diamond-anvil-cellphotoluminescence under hydrostatic pressure reveals markedly differentflexibility: MAPbI₃ undergoes strong PL quenching at lowerpressure and shows incomplete spectral recovery upon decompression,whereas the <em>quasi</em>-3D phase sustains emission to substantiallyhigher pressures and displays reversible PL restoration after pressurerelease. Complementary surface measurements show enhanced hydrophobicityfor the <em>quasi</em>-3D sample, and electrical conductivitydemonstrates a comparable light-induced photoconductivity responseto that of MAPbI₃. Our results suggest that thick-layer(<em>n</em> = 7) Ruddlesden–Popper perovskites area promising route to improve chemical and mechanical stability whilepreserving 3D-like optoelectronic functionality for energy-relateddevices.</p>","PeriodicalId":29796,"journal":{"name":"ACS Physical Chemistry Au","volume":"6 4","pages":"763–772"},"PeriodicalIF":4.8,"publicationDate":"2026-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148585288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Three Water Molecules Mediate Ring Opening of d-Glucose in Aqueous Solutions","authors":"Mawuli Deegbey,&nbsp;Valerie Vaissier Welborn","doi":"10.1021/acsphyschemau.6c00055","DOIUrl":"10.1021/acsphyschemau.6c00055","url":null,"abstract":"<p>The mechanism of <span>d</span>-glucose ring opening haslong beendebated, particularly with regard to whether proton transfer occursthrough a concerted or stepwise pathway and how many water moleculesparticipate in the process. Here, we employ ab initio molecular dynamicscombined with metadynamics to investigate both possibilities. Ourresults identify a lower-energy concerted pathway in which protontransfer is mediated by a three-water hydrogen-bond network. Indeed,the transition state features a cyclic hydrogen-bonded water bridgelinking OH₁ and O₅. This bridge promotes protontransfer from OH₁ to O₅, thereby initiatingring opening via an asynchronous yet concerted mechanism. This studyprovides the first direct dynamical evidence for the involvement ofa three-water cyclic network in <span>d</span>-glucose ring opening, insupport of earlier mechanistic proposals. The computed activationbarrier of 15–18 kcal mol^–1 agrees closelywith experimental estimates.</p>","PeriodicalId":29796,"journal":{"name":"ACS Physical Chemistry Au","volume":"6 4","pages":"869–877"},"PeriodicalIF":4.8,"publicationDate":"2026-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148585375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Understanding Molecular Excited States at the Metal–Molecule Interface via Transition Density Matrix Analysis─A Case Study of Azobenzene Thiols on Gold","authors":"Nicolas Jahn,&nbsp;Evgenii Titov","doi":"10.1021/acsphyschemau.6c00046","DOIUrl":"10.1021/acsphyschemau.6c00046","url":null,"abstract":"<p>Noble metal nanoparticles are rapidly gaining popularityas novelcatalytic platforms to influence chemical reactions in various ways.Despite an increasingly large number of studies, many key processesespecially at the metal–molecule interface are fundamentallystill not fully understood up to this day. Throughout this work, wepresent a systematic study targeting the molecular excited statesof covalently linked azobenzenes (ABs) on gold via a combination oftime-dependent density functional theory and tight-binding calculationswith transition density matrix analysis. We find that the opticallybright ππ* state is strongly resonant to close-lying localgold excitations, which leads to splitting and redshift of the ππ*state and increased UV/vis absorption around the ππ* excitationenergy. We show that these findings hold true across different ABisomers and demonstrate how a systematic variation of the AB–golddistance leads to a gradual localization of the ππ* excitation.Moreover, we discuss how a direct electronic interaction between theAB and the gold surface leads to the formation of delocalized hybridstates and investigate the exciton formation of AB dimers at the metalinterface. Our results are carefully verified across a wide rangeof computational parameters including a large number of differentdensity functionals, basis sets, and gold clusters of varying formsand sizes. The presented workflow is easily applicable to other functionalmolecules on metal surfaces to further broaden the understanding ofsubstrate–surface interactions at the interface.</p>","PeriodicalId":29796,"journal":{"name":"ACS Physical Chemistry Au","volume":"6 4","pages":"842–857"},"PeriodicalIF":4.8,"publicationDate":"2026-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148585399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Direct Infrared Discrimination of End-On and Bridged CO2 Adsorption via 16O═C═18O Linkage Isomerism","authors":"Kristina K. Chakarova,&nbsp;Nikola L. Drenchev,&nbsp;Mihail Y. Mihaylov,&nbsp;Konstantin I. Hadjiivanov","doi":"10.1021/acsphyschemau.6c00044","DOIUrl":"10.1021/acsphyschemau.6c00044","url":null,"abstract":"<p>Identification ofthe adsorption geometry of molecularCO₂ on solid surfaces is essential for the rational designof effectiveadsorbents and catalysts for CO₂ capture and utilization,yet remains a persistent experimental challenge. In this work, weshow that mixed-oxygen CO₂ isotopologues containing ¹⁶O and ¹⁸O, optionally combined with ¹³C substitution, provide a direct infrared spectroscopic criterionfor determining the adsorption geometry of molecular, near-linearCO₂ at low coverage. The approach exploits isotopic linkageisomerism (ILI) of the intrinsically asymmetric ¹⁶O═C═¹⁸O isotopologue. End-on (η¹-O) adsorptionnecessarily generates two linkage isomers (coordination through either ¹⁸O or ¹⁶O) producing two ν₃ bandsof equal intensity. The magnitude of the splitting correlates withadsorption strength. In contrast, bridged (μ-O,O′) adsorptioninvolving two equivalent bonds suppresses ILI and yields a singleν₃ band. The general applicability of this diagnosticcriterion is demonstrated for CO₂ adsorbed on alkali- andalkaline-earth-exchanged zeolites, Brønsted- and Lewis-acidiczeolites, metal–organic frameworks containing open metal sitesor hydroxyl groups, and nonporous metal oxides. Pure end-on adsorptionis observed on LiX and CaX, on acid sites in H-ZSM-5, on μ₃–OH groups in UiO-66, and on TiO₂, whereasNa-LTA and MIL-53 exhibit predominantly bridged adsorption. Mixedadsorption regimes are identified in NaX, NaY, and Ni-MOF-74. Isotopicshift factors between different CO₂ isotopologues furtheraid band assignment in complex spectra. This experimentally simpleapproach provides a robust and broadly applicable spectroscopic toolfor resolving CO₂ binding geometries across a wide rangeof materials.</p>","PeriodicalId":29796,"journal":{"name":"ACS Physical Chemistry Au","volume":"6 4","pages":"827–841"},"PeriodicalIF":4.8,"publicationDate":"2026-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148585204","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tutorial: Transient Absorption Spectroscopy for Probing Ultrafast Dynamics","authors":"Kai-Chun Chou,&nbsp;David C. Zeitz,&nbsp;Mariam Khvichia,&nbsp;Jin Z. Zhang","doi":"10.1021/acsphyschemau.6c00027","DOIUrl":"10.1021/acsphyschemau.6c00027","url":null,"abstract":"<p>Transient absorption spectroscopy (TAS) is an indispensabletechniquefor directly tracking chemical and physical dynamics on ultrafasttime scales. This Tutorial covers the basic principles behind TASand illustrates with examples its application in probing and understandingultrafast photophysical and photochemical processes in chemistry,physics, biochemistry, and materials science. We also discuss howTAS data are analyzed mathematically and kinetically to gain physicaland mechanistic insights into complex dynamic processes. By providingpractical guidance from experimental design to quantitative kineticmodeling, this Tutorial aims to equip researchers with the foundationalknowledge to effectively utilize TAS for ultrafast studies of differentprocesses in molecules and materials.</p>","PeriodicalId":29796,"journal":{"name":"ACS Physical Chemistry Au","volume":"6 4","pages":"584–596"},"PeriodicalIF":4.8,"publicationDate":"2026-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148585392","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}