The Journal of Physical Chemistry A最新文献

{"title":"Theoretical Insights on the Excited State Deactivation Mechanism in Protonated Adenosine","authors":"Mohammad Salehi,&nbsp;Pierre Çarçabal and Reza Omidyan*,&nbsp;","doi":"10.1021/acs.jpca.4c0649610.1021/acs.jpca.4c06496","DOIUrl":"https://doi.org/10.1021/acs.jpca.4c06496https://doi.org/10.1021/acs.jpca.4c06496","url":null,"abstract":"<p >We present herein our computational exploration of the conformational landscape and photophysical properties of protonated adenosine (AdoH⁺). Several different protonated isomers and conformers have been considered and their relevant photophysical properties have been addressed. From our <i>ab initio</i> quantum computational results, an S₁/S₀ conical intersection (CI) has been located for all considered conformers, providing a significant route for the ultrafast deactivation mechanism of the S₁ excited state of AdoH⁺. Our results are also supported by nonadiabatic dynamics (NAD) simulation results indicating the S₁ excited state lifetime of 240–300 fs for the two most stable conformers of AdoH⁺ (i.e., the most stable <i>syn</i>- and <i>anti</i>-N₃ protonated tautomers), which is comparable with protonated adenine, reported in the literature. The results confirm the ultrafast deactivation mechanism as well as photostability in nucleosides in protonated form.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"128 50","pages":"10851–10860 10851–10860"},"PeriodicalIF":2.7,"publicationDate":"2024-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142850001","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":"Binding of Sulfates and Water to Monovalent Cations","authors":"Mark J. Stevens*,&nbsp; and ,&nbsp;Susan B. Rempe*,&nbsp;","doi":"10.1021/acs.jpca.4c0545410.1021/acs.jpca.4c05454","DOIUrl":"https://doi.org/10.1021/acs.jpca.4c05454https://doi.org/10.1021/acs.jpca.4c05454","url":null,"abstract":"<p >The binding of the sulfate ligand group to monovalent cations in the presence of water is important for many systems. To understand the structure and energetics of sulfate complexes, we use density functional theory to study ethyl sulfate binding to the monovalent cations Li⁺, Na⁺, and K⁺, and to water. The free energies of binding and optimal structures are calculated for a range of the number of ethyl sulfates and waters. Without water, the most optimal structure for all the cations is bidentate binding by two ethyl sulfates, yielding a 4-fold coordination. With water, the lowest free energy structures also have two ethyl sulfates, but the coordination varies with cations. For complexes with water, the four oxygen atoms in the sulfate group enable multiple binding geometries for the cations and for hydrogen bonding with water. Many of these geometries differ in free energy by only a small amount (1–2 kcal/mol), meaning there will be multiple binding configurations in bulk solution. In comparison to the optimal structures for binding to the carboxylate group, there is more variation for binding to the sulfate group as a function of cation type and the number of waters. The polarization of the atoms is significant and varies among the sulfate oxygen atoms. The water oxygen charge is often larger than that of sulfate oxygen, which plays a role in the preference for monodentate ligand binding to cations in the presence of water.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"128 50","pages":"10785–10795 10785–10795"},"PeriodicalIF":2.7,"publicationDate":"2024-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142842723","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":"Evaluating the Importance of Conformers for Understanding the Vacuum-Ultraviolet Spectra of Oxiranes: Experiment and Theory","authors":"Ian T. Beck,&nbsp;Erica C. Mitchell,&nbsp;Annabelle Webb Hill,&nbsp;Justin M. Turney,&nbsp;Brandon Rotavera* and Henry F. Schaefer III*,&nbsp;","doi":"10.1021/acs.jpca.4c0439110.1021/acs.jpca.4c04391","DOIUrl":"https://doi.org/10.1021/acs.jpca.4c04391https://doi.org/10.1021/acs.jpca.4c04391","url":null,"abstract":"<p >Vacuum-ultraviolet (VUV) absorption spectroscopy enables electronic transitions that offer the unambiguous identification of molecules. As target molecules become more complex, multifunctional species present a great challenge to both experimental and computational spectroscopy. This research reports both experimental and theoretical studies of oxiranes. Computationally, the nuclear ensemble approach has been used to accurately predict experimental spectra for a variety of molecules. However, this approach incurs great computational cost, as ensembles generally consist of thousands of geometries. The present study aims to drastically reduce the ensemble by evaluating the significance of the conformers to the predicted spectra. This approach was applied to 11 substituted oxiranes using the Conformer Rotamer Ensemble Sampling Tool (CREST) of Grimme to generate an ensemble of unique conformers determined by their Boltzmann populations. Five TD-DFT functionals (BMK, CAM-B3LYP, M06-2X, MN15, ωB97X-D) and EOM-CCSD were used to simulate the spectrum of each substituted oxirane ensemble. Computed spectra were then compared to the experiment using both qualitative and quantitative metrics. Based on these metrics, it was observed that certain conformers may not be necessary to characterize this set of oxiranes despite the temperature (323 K) of the experiment. A single conformer can then be used with TD-DFT and EOM-CCSD to replicate the experimental spectra of these medium-sized combustion species.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"128 50","pages":"10906–10920 10906–10920"},"PeriodicalIF":2.7,"publicationDate":"2024-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acs.jpca.4c04391","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142842705","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":"Informing Empirically Fitted Density Functionals about the Physics of Interelectronic Interactions","authors":"Timofey V. Losev*,&nbsp;Ilya D. Ivanov,&nbsp;Igor S. Gerasimov,&nbsp;Nikolai V. Krivoshchapov and Michael G. Medvedev*,&nbsp;","doi":"10.1021/acs.jpca.4c0508510.1021/acs.jpca.4c05085","DOIUrl":"https://doi.org/10.1021/acs.jpca.4c05085https://doi.org/10.1021/acs.jpca.4c05085","url":null,"abstract":"<p >Further progress in constructing highly accurate density functionals by enforcing known laws of interelectron interactions is slow, so fitting techniques are usually employed nowadays. These approaches were shown to lead to overfitting when a functional becomes unreliable for properties on which it was not trained on. An approach to maintain the correct physical behavior of a functional during its training is required to build more complex and accurate functionals, including those based on neural networks. We devise such an approach and apply it to reparameterize the heavily fitted and popular M06-2X functional on its original training set. The resulting physics-informed functionals piM06-2X and piM06-2X-DL approached the accuracy of M06-2X in thermochemical tasks and the accuracy of PBE0 in electron densities, taking the best out of both worlds. Surprisingly, we find that a very similar performance can be achieved directly by using the PBE-2X functional without any fitting. The proposed approach should be indispensable for training future neural-network-based functionals.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"128 50","pages":"10921–10928 10921–10928"},"PeriodicalIF":2.7,"publicationDate":"2024-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142842706","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":"Single-Sided Delocalized Polarization of the C60 Cage and Reduced Infrared Intensities and Dipole Moment of H2O@C60","authors":"Hajime Torii*,&nbsp;Shumpei Sadai,&nbsp;Yoshifumi Hashikawa*,&nbsp;Yasujiro Murata and Yuka Ikemoto*,&nbsp;","doi":"10.1021/acs.jpca.4c0707210.1021/acs.jpca.4c07072","DOIUrl":"https://doi.org/10.1021/acs.jpca.4c07072https://doi.org/10.1021/acs.jpca.4c07072","url":null,"abstract":"<p >The C₆₀ fullerene cage can encapsulate a small molecule like water and provides room to leave the encapsulated component rather isolated, but the true nature of the intracomplex interactions should be further elucidated for better understanding and utility of this series of complexes. Here, an analysis toward this goal is conducted for H₂O@C₆₀ by infrared spectral measurements and theoretical calculations. It is shown that the response of the π electrons of the C₆₀ cage upon encapsulating a water molecule is single-sided and delocalized in that the electron density is partially transferred from the −<i>z</i> side to the +<i>z</i> side of the cage (when the <i>z</i> axis is taken along the water dipole) but almost only inside the cage, explaining the significant reduction of the dipole moment and the infrared intensities. Those infrared intensities have a large temperature dependence in a way that the bands gain intensities upon lowering the temperature down to 10 K, possibly due to coupling with lattice phonons.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"128 50","pages":"10867–10874 10867–10874"},"PeriodicalIF":2.7,"publicationDate":"2024-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142850002","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":"Magnetic and Thermodynamic Computations for Supramolecular Assemblies between a Cr(III) and Fe(III) Single-Ion Magnet and an Fe(II) Spin-Crossover Complex","authors":"Angel Albavera-Mata,&nbsp;Shuanglong Liu,&nbsp;Hai-Ping Cheng,&nbsp;Richard G. Hennig* and S. B. Trickey*,&nbsp;","doi":"10.1021/acs.jpca.4c0672310.1021/acs.jpca.4c06723","DOIUrl":"https://doi.org/10.1021/acs.jpca.4c06723https://doi.org/10.1021/acs.jpca.4c06723","url":null,"abstract":"<p >Experimental results on two supramolecular complexes in which a Cr^III or Fe^III d-orbital single-ion magnet center is embedded between a pair of Fe^II spin-crossover moieties make those two complexes interesting as possible candidates for use in quantum information technologies. We report detailed computational results for their structure and electronic properties and use the resulting data to parametrize a spin Hamiltonian that facilitates comparison with experimental results and their interpretation. Consistent with experimental results on decoherence in [Fe(ox)₃]@[Fe₂L₃]⁺, we find it to be easy-plane type while the [Cr(ox)₃]@[Fe₂L₃]⁺ system is easy-axis type.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"128 50","pages":"10929–10935 10929–10935"},"PeriodicalIF":2.7,"publicationDate":"2024-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142849855","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":"Cu(II) Stability and UV-Induced Electron Transfer in a Metal-Organic Hybrid: An EPR, DFT, and Crystallographic Characterization of Copper-Doped Zinc Creatininium Sulfate.","authors":"Michael J Colaneri, Simon J Teat, Jacqueline Vitali","doi":"10.1021/acs.jpca.4c06133","DOIUrl":"10.1021/acs.jpca.4c06133","url":null,"abstract":"<p><p>Single-crystal X-ray diffraction and electron paramagnetic resonance (EPR) spectroscopic experiments, complemented by quantum chemical DFT calculations, were carried out on the copper-doped metal-organic hybrid and Tutton salt analogue zinc creatininium sulfate to determine its crystal structure, to characterize the electronic structure of the doped Cu(II) binding site, and to propose a pathway for an excited-state, proton-coupled electron transfer (PCET) process in UV-exposed crystals. The crystal structure is isomorphous to that of cadmium creatininium sulfate, which has the transition ion, not in direct coordination with the creatinine, but forming a hexahydrate complex, which is bridged to a creatininium through an intervening sulfate ion. The EPR <b>g</b> (2.446, 2.112, 2.082) and copper hyperfine (<b>A</b>^<b>Cu</b>: -327, -59.6, 10.8 MHz) tensor parameters are consistent with doped copper replacing host zinc in the metal-hexahydrate complex. These parameters are similar to those observed for copper hexahydrate in doped Tutton salt systems at low temperature, where the unpaired electron occupies mainly the copper 3<i>d</i>_{<i>x</i>²-<i>y</i>²} orbital. At room temperature in the Tutton systems, vibration couplings stemming from a dynamic Jahn-Teller effect cause tensor averaging which results in a reduction in their maximum <i>g</i>-tensor and hyperfine tensor values. However, like for the doped isomorphous Cd creatinine crystal, the Cu(II) EPR exhibits little, or no room temperature averaging compared to its low temperature pattern. Samples exposed to 254 nm UV light generate a carbon-centered free radical species, characterized by an isotropic g-tensor (<i>g</i> = 2.0029) and an alpha-proton hyperfine coupling (-24 -14 +4 G). These parameters identify it as a creatinine radical cation formed by the oxidative release of one of its C2 methylene hydrogens. DFT calculations confirm the unpaired electronic structures of both the Cu(II) site and free radical. The growth in radical concentration with an increase in the UV exposure time coincides with a decrease in the copper EPR signal, indicating a coupled light-induced oxidation reduction process. A comparison of the crystal structure with the EPR parameters and DFT results provides evidence for a UV-induced PCET.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":"10380-10394"},"PeriodicalIF":2.7,"publicationDate":"2024-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11626505/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142674511","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":"Excited-State Hund's Rule Violations in Bridged [10]- and [14]Annulene Perimeters.","authors":"J Terence Blaskovits, Clémence Corminboeuf, Marc H Garner","doi":"10.1021/acs.jpca.4c06726","DOIUrl":"10.1021/acs.jpca.4c06726","url":null,"abstract":"<p><p>Molecules with Hund's rule violations between low-lying singlet and triplet states may enable a new generation of fluorescent emitters. However, only a few classes of molecules are known with this property at the current time. Here, we use a high-throughput screening algorithm of the FORMED database to uncover a class of compounds where the first excited state violates Hund's rule. We examine this class of bridged [10]- and [14]annulene perimeters with saturated bridges, and relate them to known conjugated polycyclic systems with Hund's rule violations. Despite the structural similarities with the related class of nonalternant polycyclic hydrocarbons, the mechanism is different in these bridged annulene perimeters. Here, two molecular orbital configurations contribute to each excited state. Consequently, a Hund's rule violation can only be unambiguously assigned based on the symmetry of the lowest excited singlet and triplet states. With several examples of synthetically realistic molecules, the class of bridged [10]- and [14]annulenes thus provides a structural link between the known nonalternant and alternant (azaphenalene) classes of molecules violating Hund's rule. These design principles may open avenues for the identification of new types of molecules where the order of the photophysically relevant first excited singlet and triplet states are inverted.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":" ","pages":"10404-10412"},"PeriodicalIF":2.7,"publicationDate":"2024-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142680139","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":"Engineering of Rotational Dynamics via Polymorph Manipulation","authors":"Alfred Błażytko,&nbsp;Marzena Rams-Baron*,&nbsp;Maria Książek,&nbsp;Joachim Kusz,&nbsp;Marek Matussek,&nbsp;Joanna Grelska and Marian Paluch,&nbsp;","doi":"10.1021/acs.jpca.4c0496410.1021/acs.jpca.4c04964","DOIUrl":"https://doi.org/10.1021/acs.jpca.4c04964https://doi.org/10.1021/acs.jpca.4c04964","url":null,"abstract":"<p >We used dielectric spectroscopy to uncover the rotational dynamics of the fluorophenyl rotor in different polymorphs of two amphidynamic crystals with identical sizable cores. The rotor solid-state dynamics were investigated in various crystalline environments. We did not change the chemical structure of the crystal itself, but while maintaining the same atomic composition, we changed the arrangement of atoms in space by taking advantage of crystal polymorphism, providing an alternative approach to one based on searching for new, chemically different entities with desirable functionality. We demonstrated that via polymorph variation, we can efficiently improve rotor solid-state performance and reduce the rotational barrier height by 30%. Our findings advance the understanding of polymorph engineering as a prospective trend in amphidynamic crystal technology, which uses the phenomenon of crystal polymorphism to design crystals displaying applicable internal rotational dynamics.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"128 50","pages":"10758–10765 10758–10765"},"PeriodicalIF":2.7,"publicationDate":"2024-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142842431","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":"Correlation between Noncovalent Bond Strength and Spectroscopic Perturbations within the Lewis Base","authors":"Steve Scheiner*,&nbsp;Mariusz Michalczyk* and Wiktor Zierkiewicz,&nbsp;","doi":"10.1021/acs.jpca.4c0738210.1021/acs.jpca.4c07382","DOIUrl":"https://doi.org/10.1021/acs.jpca.4c07382https://doi.org/10.1021/acs.jpca.4c07382","url":null,"abstract":"<p >Me₂CO was allowed to interact with 20 different Lewis acids so as to engage in various sorts of noncovalent interactions, encompassing hydrogen, halogen, chalcogen, pnictogen, and tetrel bonds. Density functional theory computations evaluated the interaction energy of each dyad, which was compared with spectroscopic, geometric, AIM, and energy decomposition elements so as to elucidate any correlations. The red shift of the C═O stretching frequency, and the changes in the nuclear magnetic resonance shielding of the O and C atoms of acetone, are closely correlated with the interaction energy so can be used to estimate the latter from experimental measurements. The standard AIM measures at the bond critical point, ρ, ∇²ρ, and <i>V</i> also correlate with the energy, albeit not as well as the spectroscopic parameters. The σ-hole depth on the Lewis acid is not well correlated with the energetics, due in part to the fact that electrostatics in general are not an accurate metric of bond strength.</p>","PeriodicalId":59,"journal":{"name":"The Journal of Physical Chemistry A","volume":"128 50","pages":"10875–10883 10875–10883"},"PeriodicalIF":2.7,"publicationDate":"2024-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142850062","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}