The Journal of Physical Chemistry A最新文献

{"title":"Understanding Anionic Hyperporphyrins: TDDFT Calculations on Peripherally Deprotonated <i>meso</i>-Tetrakis(4-hydroxyphenyl)porphyrin.","authors":"Jeanet Conradie, Carl C Wamser, Abhik Ghosh","doi":"10.1021/acs.jpca.4c07216","DOIUrl":"https://doi.org/10.1021/acs.jpca.4c07216","url":null,"abstract":"<p><p>Presented herein is a DFT/TDDFT study of <i>meso</i>-tetrakis(4-hydroxyphenyl)porphyrin (H₂[THPP]) and its <i>O</i>-deprotonated tetraanionic form; the latter was modeled as both a free tetraanion and with various counterions. Based on our calculations, the experimentally observed hyperporphyrin spectra are attributed to an admixture of phenol/phenoxide character into the a_2u-type HOMO of tetraphenylporphyrin. The admixture results in an elevation of the orbital energy of the HOMO in relation to other frontier orbitals, which accounts for the observed spectral redshifts. The calculations underscore differences in the performance of different exchange-correlation functionals. Thus, while the popular hybrid functional B3LYP greatly exaggerates the redshift of the far-red hyperporphyrin band of <i>O</i>-deprotonated H₂[THPP], the range-separated functional CAMY-B3LYP predicts a more moderate redshift. The latter, however, fails to reproduce experimentally observed absorptions in the 550-600 nm range, potentially underscoring the still imperfect modeling of anionic hyperporphyrins.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143062518","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":"Kinetics and Mechanism of the Thermal Isomerization of Cyclopropane to Propene: A Comprehensive Theoretical Study.","authors":"Yeljair Monascal, María P Badenes","doi":"10.1021/acs.jpca.4c05315","DOIUrl":"10.1021/acs.jpca.4c05315","url":null,"abstract":"<p><p>The kinetics of the homogeneous gas-phase thermal isomerization of cyclopropane to propene has been studied theoretically to clarify existing discrepancies regarding the interpretation of its mechanism. High-level <i>ab initio</i> and density functional theory calculations were used to determine the branching ratios of the biradical and carbene reaction channels over wide temperature and pressure ranges. For this, relevant molecular and thermochemical properties of the proposed intermediates and related transition states were computed and compared with literature values. The Arrhenius equation, derived between 400 and 1400 K in the high-pressure limit at the CCSD(T)/6-311++G(3df,3pd)//CCSD/6-311++G(d,p) level of theory, is given by log₁₀(<i>k</i>_overall,∞/s^-1) = (15.60 ± 0.06) - (65.70 ± 0.17) kcal mol^-1 (2.303 RT)^-1. This expression is in very good agreement with the available experimental data. According to these results, the biradical pathway is the predominant mechanism, while the carbene pathway contributes 1-2% at higher temperatures. The G4//B3LYP/6-311++G(3df,3pd) and G4//M06-L/6-311++G(3df,3pd) levels showed comparable Arrhenius parameters. Low-pressure limit rate coefficients and falloff curves were also estimated to evaluate the effect of pressure on the reaction. Additionally, the possibility of a concerted path is considered, but calculations showed unstable wave functions, suggesting that this mechanism would not be plausible.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":"894-908"},"PeriodicalIF":2.7,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142714876","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":"Dinitrogen Activation: A Novel Approach with P/B Intermolecular FLP.","authors":"Swapan Sinha, Santanab Giri","doi":"10.1021/acs.jpca.4c05125","DOIUrl":"10.1021/acs.jpca.4c05125","url":null,"abstract":"<p><p>This study explores the reactivity of a new intermolecular P/B frustrated Lewis pair in the context of dinitrogen activation through a push-pull mechanism. The ab initio molecular dynamics model known as atom-centered density matrix propagation plays a pivotal role in elucidating the weakly associated encounter complex. In-depth analysis, mainly through intrinsic reaction coordinate calculations, supports a single-step mechanism. Notably, N₂ activation is observed to proceed through a concerted mechanism, proving slightly endergonic in solvents like toluene and hexane. Furthermore, density functional theory calculations reveal that the N₂ activation reaction becomes kinetically and thermodynamically favorable when it is subjected to a moderately oriented external electric field of 2.57 V nm^-1 along the reaction axis. In addition, natural bonding orbital and extended transition state-natural orbitals for chemical valence analyses contribute to a more profound comprehension of the electron-transfer processes integral to the chemical reaction.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":"885-893"},"PeriodicalIF":2.7,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142996323","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":"Electronically Nonadiabatic Quenching of Excited States of O₂ by Collisions with O Atoms.","authors":"Dandan Lu, Yinan Shu, György Lendvay, Donald G Truhlar, Hua Guo","doi":"10.1021/acs.jpca.4c07991","DOIUrl":"https://doi.org/10.1021/acs.jpca.4c07991","url":null,"abstract":"<p><p>The kinetics of electronically inelastic quenching of O₂(<i>a</i>¹Δ_<i>g</i>) and O₂(<i>b</i>¹Σ_<i>g</i>⁺) by collisions with O(³P) have been investigated using mixed quantum-classical trajectories governed by adiabatic potential energy surfaces and state couplings generated from a recently developed diabatic potential energy matrix (DPEM) for the 14 lowest-energy ³A' states of O₃. Using the coherent switching with decay of mixing (CSDM) method, dynamics calculations were performed both with 14 coupled electronic states and with 8 coupled electronical states, and similar results were obtained. The calculated thermal quenching rate coefficients are generally small, but they increase with temperature. The positive temperature dependence is attributed to high-energy locally avoided crossings that can only be easily accessed by high collision energies. We find that, depending on the temperature, 86-97% of the <i>b</i> state quenches are into the <i>a</i> state with the remainder into the ground electronic state of O₂. The calculated rate coefficients for quenching of O₂(<i>b</i>¹Σ_<i>g</i>⁺) and O₂(<i>a</i>¹Δ_<i>g</i>) by O(³P), coupled with the assumption that electronically nonadiabatic probabilities for collisions on the ³A' surfaces are similar to those on ³A″ surfaces, are compared with the available experimental results.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143062490","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":"Systematic Study of Hard-Wall Confinement-Induced Effects on Atomic Electronic Structure.","authors":"Hugo Åström, Susi Lehtola","doi":"10.1021/acs.jpca.4c05641","DOIUrl":"https://doi.org/10.1021/acs.jpca.4c05641","url":null,"abstract":"<p><p>We point out that although a litany of studies have been published on atoms in hard-wall confinement, they have either not been systematic, having only looked at select atoms and/or select electron configurations, or they have not used robust numerical methods. To remedy the situation, we perform in this work a methodical study of atoms in hard-wall confinement with the HelFEM program, which employs the finite element method that trivially implements the hard-wall potential, guarantees variational results, and allows for easily finding the numerically exact solution. Our fully numerical calculations are based on nonrelativistic density functional theory and spherically averaged densities. We consider three levels of density functional approximations: the local density approximation employing the Perdew-Wang (PW92) functional, the generalized-gradient approximation (GGA) employing the Perdew-Burke-Ernzerhof (PBE) functional, and the <i>meta</i>-GGA approximation employing the r²SCAN functional. Importantly, the completely dissimilar density functional approximations are in excellent agreement, suggesting that the observed results are not artifacts of the employed level of theory. We systematically examine low-lying configurations of the H-Xe atoms and their monocations and investigate how the configurations─especially the ground-state configuration─behave as a function of the position of the hard-wall boundary. We perform calculations with both spin-polarized as well as spin-restricted densities and demonstrate that spin-polarization effects are significant in open-shell configurations, even though some previous studies have only considered the spin-restricted model. We demonstrate the importance of considering ground-state changes for confined atoms by computing the ionization radii for the H-Xe atoms and observe significant differences to earlier studies. Confirming previous observations, we identify electron shifts on the outermost shells for a majority of the elements: valence s electrons are highly unfavored under strong confinement, and the high-lying 3d and 4f orbitals become occupied in atoms of periods 2-3 and 3-4, respectively. We also comment on deficiencies of a commonly used density-based estimate for the van der Waals (vdW) radius of atoms and propose a better behaved variant in terms of the number of electrons outside the vdW radius that we expect will prove useful in future studies.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143057499","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":"σ-Electrons rather than π-Electrons Inducing Sensitive Nonlinear Optical Responses in Planar and Quasi-Planar Boron Clusters.","authors":"Quanjie Zhong","doi":"10.1021/acs.jpca.4c07488","DOIUrl":"https://doi.org/10.1021/acs.jpca.4c07488","url":null,"abstract":"<p><p>Geometries and electronic structures of planar and quasi-planar boron clusters resemble those of aromatic hydrocarbons, providing opportunities for designing novel nonlinear optical materials. However, the nonlinear optical properties, optical-response mechanisms, and optimal optical-response geometries of boron clusters remain unclear. Accordingly, this study addresses these uncertainties. Boron clusters exhibit good nonlinear optical performance, significantly surpassing that of aromatic hydrocarbons of comparable size. An analysis method based on electron density decomposition is proposed to quantitatively determine the contributions of σ- and π-electrons to the optical responses. The findings reveal that σ-electrons dominate the nonlinear optical responses in planar boron clusters owing to their delocalized characteristics, in marked contrast to aromatic hydrocarbons. Using boron isomers as model systems, boron nanoribbons were confirmed to provide optimal nonlinear optical performances. This study offers valuable insights into the nonlinear optical behaviors of planar and quasi-planar boron clusters, substantially enhancing the rational design of novel nonlinear optical materials.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143057500","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":"Transformation of Distinct Superatoms to Superalkalis by Successive Ligation of Thymine Nucleobases.","authors":"Wen-Lu Wang, Zhi-Chao Zhang, Shu-Ying Huang, Hai-Yan Zhong, Bi-Lian Ni, Wei-Ming Sun","doi":"10.1021/acs.jpca.4c08440","DOIUrl":"https://doi.org/10.1021/acs.jpca.4c08440","url":null,"abstract":"<p><p>The ligation strategy has been widely used in the chemical synthesis of atomically precise clusters. A series of thymine (T)-ligated Al₁₂<i>M</i>-T<i>_n</i> (<i>M</i> = Be, Al, C; <i>n</i> = 1-5) complexes have been studied to reveal the effect of DNA nucleobase ligands on the electronic structures of different superatoms in the present work. In addition to its protective role, the successive attachment of thymine ligands significantly lowers the adiabatic ionization energies (AIEs) of the studied Al₁₂<i>M</i> superatoms with filled and unfilled electronic shells. The continuous decrease in the AIEs of Al₁₂<i>M</i>-T<i>_n</i> is derived from the gradually raised highest occupied molecular orbital (HOMO) levels upon the addition of ligands. Interestingly, the lowering degree of AIEs for such nucleobase-protected superatoms is independent of the distinct shell fillings of Al₁₂<i>M</i> superatoms but is significantly related to the types of nucleobases. Moreover, the obtained Al₁₂<i>M</i>-T₅ superalkalis not only exhibit excellent performance in activating the stable CO₂ and O₂ molecules but also have considerable nonlinear optical (NLO) responses. We, therefore, hope that this study could provide a viable strategy for synthesizing novel nucleobase-ligated superatom clusters with excellent reducing capability to enrich the family of multifunctional nanoclusters.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143062516","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":"Bioaerosol Characterization with Vibrational Spectroscopy: Overcoming Fluorescence with Photothermal Infrared (PTIR) Spectroscopy.","authors":"Jia H Shi, Carlie J Poworoznek, Rebecca L Parham, Katherine R Kolozsvari, Nicole E Olson, Yao Xiao, Ziying Lei, Johnna A Birbeck, Stephen J Jacquemin, Judy A Westrick, Andrew P Ault","doi":"10.1021/acs.jpca.4c07848","DOIUrl":"https://doi.org/10.1021/acs.jpca.4c07848","url":null,"abstract":"<p><p>Aerosols containing biological material (i.e., bioaerosols) impact public health by transporting toxins, allergens, and diseases and impact the climate by nucleating ice crystals and cloud droplets. Single particle characterization of primary biological aerosol particles (PBAPs) is essential, as individual particle physicochemical properties determine their impacts. Vibrational spectroscopies, such as infrared (IR) or Raman spectroscopy, provide detailed information about the biological components within atmospheric aerosols but these techniques have traditionally been limited due to the diffraction limit of IR radiation (particles >10 μm) and fluorescence of bioaerosol components overwhelming the Raman signal. Herein, we use photothermal infrared spectroscopy (PTIR) to overcome these limitations and characterize individual PBAPs down to 0.18 μm. Both optical-PTIR (O-PTIR) and atomic force microscopy-PTIR (AFM-PTIR) were used to characterize bioaerosol particles generated from a cyanobacterial harmful algal bloom (cHAB) dominated by <i>Planktothrix agardhii</i>. PTIR spectra contained modes consistent with traditional Fourier transform infrared (FTIR) spectra for biological species, including amide I (1630-1700 cm^-1) and amide II (1530-1560 cm^-1). The fractions of particles containing biological materials were greater in supermicron particles (1.8-3.2 μm) than in submicron particles (0.18-0.32 and 0.56-1.0 μm) for aerosolized cHAB water. These results demonstrate the potential of both O-PTIR and AFM-PTIR for studying a range of bioaerosols with vibrational spectroscopy.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143051068","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":"Energetic and Electronic Properties of AcX and LaX (X = O and F).","authors":"João G F Romeu, David A Dixon","doi":"10.1021/acs.jpca.4c08358","DOIUrl":"https://doi.org/10.1021/acs.jpca.4c08358","url":null,"abstract":"<p><p>The bonding and spectroscopic properties of LaX and AcX (X = O and F) diatomic molecules were studied by high-level ab initio CCSD(T) and SO-CASPT2 electronic structure calculations. Bond dissociation energies (BDEs) were calculated at the Feller-Peterson-Dixon (FPD) level. Potential energy curves and spectroscopic constants for the lowest-lying spin-orbit Ω states were obtained at the SO-CASPT2/aQ-DK level. A dense manifold of excited states was described for the monofluorides with the ground states well separated from the excited states. The spectroscopic parameters were in good agreement with those reported experimentally for LaO and LaF. For the diatomic molecules containing actinides, no experimental data of these parameters was found, but the results were consistent with other high-level calculations. The BDEs calculated at the FPD level were 791.3 (LaO), 705.2 (AcO), 650.0 (LaF), and 678.6 (AcF) kJ/mol. The NBO analysis showed that the monofluorides are essentially ionic, which explains why the BDE(AcF) is higher than BDE(LaF); for the monoxides, covalent contributions involving the d orbitals of the metal and the p orbitals of the oxygen are stronger for LaO than AcO, which explains the higher BDE for LaO. The bond orders are predicted to be 2 for LaF and AcF, 3 for AcO, and higher than 3 for LaO.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143057494","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":"Interplay of Tetrel, Hydrogen, and Halogen Bonds in F₃GeOCl and HCN Complexes: A Comprehensive Theoretical Study of Dimers, Trimers, and Tetramers.","authors":"Antonio Frontera, Saeedreza Emamian","doi":"10.1021/acs.jpca.4c08102","DOIUrl":"https://doi.org/10.1021/acs.jpca.4c08102","url":null,"abstract":"<p><p>This study investigates the nature and interplay of noncovalent interactions (NCIs)─tetrel bonds (TB), hydrogen bonds (HB), and halogen bonds (XB)─in molecular assemblies formed between trifluorogermyl hypochlorite (F₃GeOCl) and hydrogen cyanide (HCN). Using a combination of high-level computational methods, we explored the geometric, energetic, and electronic properties of dimers, trimers, and tetramers formed in different molar ratios of interacting reagents. Various analyses reveal a significant cooperativity between TB and HB, which mutually reinforce each other, while XB interactions are diminished in the presence of TB and HB. Energy decomposition analysis (EDA) through SAPT and sobEDAw methods identified electrostatic and orbital interactions as key contributors to the stabilization of TB and HB, while dispersion plays a prominent role in XB. A perfect linear correlation was found between interaction energy and charge density at bond critical points (BCPs), underscoring the predictive value of these metrics. These findings shed light on the cooperative nature of NCIs and provide a framework for designing molecular systems in supramolecular chemistry and crystal engineering.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143057406","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}