Bingqing Sun, Ran Ding, Chuan Liu, Xiaoyan Song, Yueyuan Mao, Lei Liu
{"title":"Sensing Mechanism of a Pyrene-Based Fluorescence Probe for TNP: Invalidity of Hydrogen Bond-Assisted Charge Transfer.","authors":"Bingqing Sun, Ran Ding, Chuan Liu, Xiaoyan Song, Yueyuan Mao, Lei Liu","doi":"10.1021/acs.jpca.5c02704","DOIUrl":"10.1021/acs.jpca.5c02704","url":null,"abstract":"<p><p>Specific detection of 2,4,6-trinitrophenol (TNP) is of fundamental importance for homeland security and environmental safety. Turn-off fluorescence sensors for TNP based on small organic fluorophores are gaining increasing attention for their excellent sensitivity and low cost. In experiment, the turn-off signal is generally attributed to the hydrogen bond-assisted charge transfer mechanism, in which the intermolecular hydrogen bond facilitates the photoinduced electron transfer (PeT) between the sensor and analyte. However, detailed computational works are usually not present to support this mechanism. This study performs a thorough investigation on the turn-off mechanism of a pyrene-based probe (PTC) for TNP with the aid of density functional theory (DFT) and time-dependent DFT (TDDFT) methods, presenting a novel π-π stacking-assisted PeT mechanism rather than the original hydrogen bond-assisted PeT mechanism. The investigation reveals that the π-π stacking model plants a lower-lying PeT state under the local excitation (LE) state of the PTC. π-π stacking, on one hand, enlarges the LUMO-LUMO gap between TNP and PTC; on the other, it renders considerable orbital overlap between the two LUMOs, which facilitates facile electron transfer from PTC to TNP and leads to fluorescence quenching. Moreover, the selectivity of the sensor in the presence of interfering nitro-aromatic compounds (NACs) is studied by taking nitrobenzene (NB) as an example. A similar PeT state is planted under the LE state in this case. However, for the first time, we observe a crossover of the PeT state and the LE state induced by NB. After photoexcitation, the PTC-NB complex will partially relax to the LE minimum via the minimal energy conical intersection (MECI) and the fluorescence is recovered. The selectivity of the sensor is well explained. This work expands our understanding of the effects of hydrogen bond and π-π stacking on the PeT process and provides new insights for the design of pyrene-based TNP sensors.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":"6272-6280"},"PeriodicalIF":2.7,"publicationDate":"2025-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144537450","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":"Benchmark Calculations of Vertical Excitation Energies for Medium-Sized Molecules Using Unitary Coupled-Cluster-Based Polarization Propagator Theory.","authors":"Huan Yu, Yu Zhang, Junzi Liu","doi":"10.1021/acs.jpca.5c01293","DOIUrl":"10.1021/acs.jpca.5c01293","url":null,"abstract":"<p><p>The unitary coupled-cluster (UCC)-based polarization propagator theory (PPT) is a novel Hermitian quantum chemical method for calculating excited states. This study benchmarks vertical excitation energies (VEEs) for medium-sized molecules using two practical schemes for UCC-PPT: UCC3 and quadratic UCCSD (qUCCSD). Their performance is evaluated and compared with the equation-of-motion coupled-cluster singles and doubles (EOM-CCSD) method and the algebraic construction (ADC) family of methods (ADC(2) and ADC(3)). The qUCCSD method achieves a mean absolute deviation (MAD) of 0.21 eV and a standard deviation (SD) of 0.20 eV with respect to theoretical best estimates (TBEs), demonstrating systematic improvements over UCC3 with a 12% lower MAD and a 26% lower SD. Among the four Hermitian excited-state methods in this work, UCC-based methods excel at describing Rydberg states but tend to underestimate VEEs for both singlet and triplet excitations. Statistical analysis reveals that UCC-based approaches are competitive with ADC(3) and outperform ADC(2) in certain cases. These findings suggest that the commutator truncation scheme within the UCC framework offers a promising path for the development of UCC-based excited-state methods.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":"6459-6469"},"PeriodicalIF":2.7,"publicationDate":"2025-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144551450","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}
Emma F Gubbins, Ziqing Xiong, Rebecca G Lynch, Blake Hance, Steven J Sibener, Mary Jane Shultz
{"title":"Phase-Sensitive SFG of Poly(vinyl alcohol) on Calcium Fluoride: Interaction with Water Using Backside Geometry.","authors":"Emma F Gubbins, Ziqing Xiong, Rebecca G Lynch, Blake Hance, Steven J Sibener, Mary Jane Shultz","doi":"10.1021/acs.jpca.4c06453","DOIUrl":"https://doi.org/10.1021/acs.jpca.4c06453","url":null,"abstract":"<p><p>One effective tool for probing interfaces at the atomic-molecular level, particularly buried interfaces, is nonlinear spectroscopy: sum frequency generation (SFG). SFG produces a complex response; the observed intensity is the square of this complex response. Removing complications due to the nonlinearity requires determining the complex amplitude. This contribution reports a nonlinear interferometric technique that nearly directly yields the real and imaginary components of the complex response via optical projection. Both the real and imaginary components are linear in the constituents generating the response, enabling monitoring interactions between individual moieties and added molecules. The technique is applied to poly(vinyl alcohol) (PVA) on a CaF<sub>2</sub> substrate. PVA is of interest since it is one of the most effective synthetic ice recrystallization inhibitors (IRIs); both its configuration at the interface and its interaction with water are thought to play critical roles in its IRI activity. Results show that PVA binds in a manner reminiscent of reported simulations of PVA binding to ice; some alcohol groups strongly bind water, chemisorbing it, while other groups weakly bind water, physisorbing it. Both the polarization dependence of the SFG response and modified intensity due to the interaction with water are leveraged to assign resonances.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144648010","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":"Virtual Screening of Novel Eco-Friendly Gaseous Dielectrics through Dimensionless Bond Decomposition and Machine Learning Algorithm.","authors":"Mi Zhang, Hua Hou, Baoshan Wang","doi":"10.1021/acs.jpca.5c03019","DOIUrl":"https://doi.org/10.1021/acs.jpca.5c03019","url":null,"abstract":"<p><p>Identification of environmentally friendly gaseous dielectrics to replace the most potent greenhouse gas SF<sub>6</sub> is urgently desired in the worldwide high-voltage electrical industry. However, the great challenge for SF<sub>6</sub>-free technology remains because of numerous contradictory requirements it has to meet simultaneously: high dielectric strength, low boiling points, low global warming potential, high arc quenching capability, low acute/subchronic inhalation toxicity, and low flammability. Herein, the chemical bonds are revealed to be the universal, unique, and unified descriptors to develop the predictive models for efficient virtual screening of novel gaseous dielectrics. By means of the automatic bond decomposition mechanism toward the dimensionless SMILES formula, excellent correlations between experiments and theory have been obtained successfully for eight types of key properties of the insulation gases using the optimized artificial neural networks. The bond-based machine-learning algorithm is stable to both training and test sets within the leveraging applicability domains. Mechanistic interpretations of the inherent coupling effect have been carried out by the normalized importance of weights of the bond descriptors. The bond-based networks were applied to a total of 3727 C, H, N, O, S, and F-containing compounds as curated from PubChem. Properties of each species were predicted, and the overall performance was ordered by scoring with respect to SF<sub>6</sub>. Although no gas could be identified to be superior to SF<sub>6</sub> in all aspects, a shortlist of promising replacement gases with well-balanced dielectric performance has been found by virtual screening and might stimulate experimental synthesis and tests for practical use. Moreover, the present work provides guidelines for the rational design of structural characteristics of novel compounds influential for gaseous dielectrics.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144657822","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}
Mark A. Blitz*, Poppy Guy, Robin Shannon and Paul W. Seakins*,
{"title":"","authors":"Mark A. Blitz*, Poppy Guy, Robin Shannon and Paul W. Seakins*, ","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"129 28","pages":"XXX-XXX XXX-XXX"},"PeriodicalIF":2.7,"publicationDate":"2025-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/pdf/10.1021/acs.jpca.5c01814","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144640798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"DFT-Driven Elucidation of Stereoselectivity in the NHC-Catalyzed Asymmetric Annulation of Cyclohexadienone-Tethered Enal.","authors":"Zheng-Yang Yi, Donghui Wei, Shihao Sun, Yang Wang","doi":"10.1021/acs.jpca.5c02105","DOIUrl":"10.1021/acs.jpca.5c02105","url":null,"abstract":"<p><p>The asymmetric catalytic potential of chiral N-heterocyclic carbenes (NHCs) has been increasingly demonstrated through stereoselective transformations. This study unravels the mechanism and origin of stereoselectivity in an NHC-catalyzed annulation of cyclohexadienone-tethered enal using density functional theory (DFT) calculations. The participation of in situ generated acetate acid has been found to be vital in both the generation of the Breslow intermediate and the esterification process. The stereoselectivity computed is found to be in very good agreement with the experimentally known enantioselectivity as well as chemoselectivity, validating the theoretical model. The origin of high stereoselectivity is traced to a series of more effective noncovalent interactions (such as π···π, C-H···O, and O-H···π) between the enolate and cyclohexadienone moieties in the lower-energy transition state. This investigation provides crucial mechanistic insights that advance both theoretical understanding of NHC-catalyzed desymmetrization strategies.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":"6226-6235"},"PeriodicalIF":2.7,"publicationDate":"2025-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144537445","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":"Outstanding Features of Rhodium Clusters for Hydrogen Adsorption and Desorption Revealed by Thermal Desorption Spectrometry.","authors":"Fumitaka Mafuné, Hayato Kurashita, Satoshi Kudoh, Ken Miyajima, Masato Yamaguchi, Toshiaki Nagata","doi":"10.1021/acs.jpca.5c02121","DOIUrl":"10.1021/acs.jpca.5c02121","url":null,"abstract":"<p><p>The adsorption of H<sub>2</sub> molecules on cationic rhodium clusters, Rh<sub><i>n</i></sub><sup>+</sup>, at 300 K and their desorption upon heating were experimentally investigated by using gas-phase thermal desorption spectrometry to assess the hydrogen storage capacity of Rh clusters. The results revealed that Rh<sub><i>n</i></sub><sup>+</sup> could store a higher amount of H<sub>2</sub> with desorption occurring at significantly lower temperatures compared to other cluster such as V<sub><i>n</i></sub><sup>+</sup> and Co<sub><i>n</i></sub><sup>+</sup>. In particular, Rh<sub>6</sub><sup>+</sup> exhibited remarkable desorption characteristics. Density functional theory calculations revealed the geometrical structures of stable Rh<sub>6</sub>H<sub><i>m</i></sub><sup>+</sup>, showing that H<sub>2</sub> molecules predominantly adsorb dissociatively on bridge sites for <i>m</i> ≤ 8 as a metal hydride, while they start to adsorb molecularly for <i>m</i> ≥ 10 forming a σ complex. The adsorption energies of H<sub>2</sub> on Rh<sub>6</sub>H<sub><i>m</i></sub><sup>+</sup> estimated from the most stable isomer aligned well with the experimental findings.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":"6236-6246"},"PeriodicalIF":2.7,"publicationDate":"2025-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144537448","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}