{"title":"Enhanced Hyperpolarizabilities Through p‐Phenylene Bridges: Computational Studies on Metamerism and Functional Molecular Properties of Pyridinium–Dicyanomethanide‐Based Zwitterions","authors":"Sanyasi Sitha","doi":"10.1002/poc.4657","DOIUrl":"https://doi.org/10.1002/poc.4657","url":null,"abstract":"Para‐phenylene‐bridged pyridinium (acceptor)–dicyanomethanide (donor)‐based zwitterions were computationally investigated and are reported here. Reichardt's metamer was found to be twisted and Brooker's metamer in near‐planar conformation. Natural bond orbital (NBO) analysis showed that mesomeric resonance is helping Brooker's metamer but found to be not helpful for Reichardt's metamer. To assess the impacts of metamerism and aromatic bridges, fundamental molecular properties like dipole moments (μ), polarizabilities (<jats:italic>α</jats:italic>), hyperpolarizabilities (<jats:italic>β</jats:italic>), and adiabatic absorptions of these two molecules were analyzed and then directly compared with their counterpart zwitterions without any bridges (<jats:italic>previously reported</jats:italic>). Results of impact of metamerism: Reichardt's metamer showed around <jats:italic>three times enhanced</jats:italic> hyperpolarizabilities (ωB97xD: <jats:italic>β</jats:italic> = 1577.1 × 10<jats:sup>−30</jats:sup> esu) than the Brooker's metamer (ωB97xD: <jats:italic>β</jats:italic> = 532.5 × 10<jats:sup>−30</jats:sup> esu). Impacts of <jats:italic>p</jats:italic>‐phenylene bridges: Compared to their respective D–A directly connected zwitterions reported previously (in ωB97xD methodology, Reichardt's: <jats:italic>β</jats:italic> = 257.2 × 10<jats:sup>−30</jats:sup> esu and Brooker's: <jats:italic>β</jats:italic> = 67.2 × 10<jats:sup>−30</jats:sup> esu), respective <jats:italic>p</jats:italic>‐phenylene‐bridged zwitterions showed <jats:italic>five to eight times enhanced</jats:italic> hyperpolarizabilities. This report highlights the better efficiencies of Reichardt's metamer over Brooker's metamer and aromatically bridged over the directly connected zwitterions. Current findings may be helpful in the designing of efficient functional molecular chromophores, and aromatic bridge combined with zwitterions can be solutions to nonlinear transparency trade‐off problem.","PeriodicalId":16829,"journal":{"name":"Journal of Physical Organic Chemistry","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142191271","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Darón I. Freedberg, Nicholas V. Hud, Max Kopelevich, Daniel J. O'Leary, Jane Strouse
{"title":"In Memoriam: The Life and Scientific Accomplishments of Frank A. L. Anet (1926–2024)","authors":"Darón I. Freedberg, Nicholas V. Hud, Max Kopelevich, Daniel J. O'Leary, Jane Strouse","doi":"10.1002/poc.4656","DOIUrl":"https://doi.org/10.1002/poc.4656","url":null,"abstract":"A memorial tribute detailing the life and scientific accomplishments of Frank A. L. Anet, a pioneer of nuclear magnetic resonance (NMR) spectroscopy who discovered bedrock principles in organic chemistry and magnetic resonance. He was the first to show that nuclear Overhauser effects could provide structural information, significantly impacting future NMR applications. In the 1960s and 1970s, he built entire multinuclear NMR spectrometers operating as high as 396 MHz for protons, detecting nuclei inaccessible to commercial instruments, and operating at very low temperatures for studying molecular structure and dynamics. A titan of physical organic chemistry, Frank made important contributions in the areas of conformational analysis, stereochemistry, isotope effects, NMR relaxation theory, and chemical origins of life.","PeriodicalId":16829,"journal":{"name":"Journal of Physical Organic Chemistry","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142191272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Michelle T. Custodio Castro, Carlos O. Della Védova, Rosana M. Romano
{"title":"Exploring Conformational Preferences in XC(W)ZY Molecules With X, Y = F, Cl, Br and W, Z = O, S, Se: Unraveling the Influence of Conjugative and Anomeric Interactions","authors":"Michelle T. Custodio Castro, Carlos O. Della Védova, Rosana M. Romano","doi":"10.1002/poc.4654","DOIUrl":"10.1002/poc.4654","url":null,"abstract":"<div>\u0000 \u0000 <p>The relative stabilities of the <i>syn</i>- and <i>anti</i>-conformers of 72 molecules belonging to the XC(W)ZY type, with X, Y = F, Cl, Br and W, Z = O, S, Se, have been computed using the B3LYP/aug-cc-pVDZ approximation. The conformational preferences, represented by the energy differences between the two rotamers, exhibit a systematic trend in relation to both the halogen atoms and the chalcogen atoms. These computational predictions are in agreement with available experimental results. The NBO formalism was employed to assess the influence of both the conjugative and anomeric interactions on the relative energy of the conformers. It has been determined that the conjugative interaction provides a satisfactory explanation for the energy differences between rotamers. In contrast, the anomeric interactions favors the <i>syn</i>-conformation in all cases. The relative stabilities between XC(W)ZY/YC(W)ZX and XC(W)ZY/XC(Z)WY constitutional isomers have also been computed and correlated with the experimental data.</p>\u0000 </div>","PeriodicalId":16829,"journal":{"name":"Journal of Physical Organic Chemistry","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142191280","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Novel Trifunctional Intramolecular Frustrated Lewis Pair Derived From Aminoboronic Acid for Converting CO2 Into Valuable Chemicals","authors":"Mohmmad Faizan, Guntupalli Santhosh, Madhumita Chakraborty, Ravinder Pawar","doi":"10.1002/poc.4655","DOIUrl":"10.1002/poc.4655","url":null,"abstract":"<div>\u0000 \u0000 <p>The conversion of CO<sub>2</sub> into valuable chemicals remains a significant challenge for achieving environmental sustainability, primarily due to the stability of the CO<sub>2</sub> molecule. This necessitates the development of efficient and ecofriendly catalysts. In recent years, frustrated Lewis pairs (FLPs) have shown promise for CO<sub>2</sub> utilization. In this study, we introduce α-aminodiboronic acid (DBA), a novel trifunctional aminoboronic acid, as an intramolecular FLP for converting CO<sub>2</sub> into cyclic carbonate and formic acid. Using density functional theory (DFT) calculations, we explored the reaction mechanism and investigated DBA's electronic structure through molecular electrostatic potential surface (MESP) and natural bond orbital (NBO) analyses. Our results reveal that one −B (OH)<sub>2</sub> group induces an unusual state of frustration in the molecule due to charge transfer from the nitrogen atom's lone pair to the π* orbitals, enhancing catalytic performance. The additional −B (OH)<sub>2</sub> group serves as an anchoring site for reactive species. The epoxide activation energy is reduced by approximately 27 kcal/mol compared to the uncatalyzed reaction, and the reduction of CO<sub>2</sub> occurs with a requirement of 26 kcal/mol. The additional −B (OH)<sub>2</sub> plays a crucial role in the catalytic mechanism and minimizes the energies of various structures observed in the reaction path. The reaction energetics align with structural analysis observations, marking this study as the first report on single-molecule trifunctional FLPs for transforming CO<sub>2</sub> into valuable chemicals.</p>\u0000 </div>","PeriodicalId":16829,"journal":{"name":"Journal of Physical Organic Chemistry","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142191319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Theoretical investigations on N2H5N5/PDO cocrystal via a first-principles study","authors":"Zhipeng Chen, Junqi Wang, Qingshan Xie, Chen Yang, Changlin Zhou","doi":"10.1002/poc.4653","DOIUrl":"10.1002/poc.4653","url":null,"abstract":"<p>The exploration of <i>cyclo</i>-N<sub>5</sub>ˉ-based energetic cocrystals represents a noteworthy avenue within pentazolate chemistry, focusing on leveraging cocrystallization to enhance stability. Recently, a novel cocrystal explosive, N<sub>2</sub>H<sub>5</sub>N<sub>5</sub>/PDO, was developed by combining N<sub>2</sub>H<sub>5</sub>N<sub>5</sub> with pyrazine 1,4-dioxide (PDO), exhibiting promising detonation characteristics and reduced sensitivity. This study endeavors to elucidate how the structure and noncovalent interactions impact the performance of N<sub>2</sub>H<sub>5</sub>N<sub>5</sub>/PDO through a first-principles investigation. The results indicate that the enhanced hydrogen bonding and wave-like crystal packing structure within the cocrystal effectively bolster its stability compared to N<sub>2</sub>H<sub>5</sub>N<sub>5</sub>. The N···H and O···H interactions, in conjunction with π–π interactions, emerge as critical elements driving cocrystal formation. Compared to the pure N<sub>2</sub>H<sub>5</sub>N<sub>5</sub>, the detonation performance of the cocrystal exhibits a slight decline, albeit with a noticeable reduction in sensitivity.</p>","PeriodicalId":16829,"journal":{"name":"Journal of Physical Organic Chemistry","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142191320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Torsional influences on cross‐conjugated thieno[3,4‐b]thiophene photochromes","authors":"Nicholas P. Adams, John D. Tovar","doi":"10.1002/poc.4650","DOIUrl":"https://doi.org/10.1002/poc.4650","url":null,"abstract":"Photoresponsive conjugated polymers are a promising target for modern organic electronics. Numerous photoswitchable repeat units have been included covalently within polymeric structures to enable responsive chromic materials, most commonly through side‐chain appendages or through formal conjugation along a π‐conjugated backbone. We recently disclosed a new design whereby the photoswitch elements are cross conjugated to a conjugated polymer main chain. In this case, we found that the extent of photoconversion was dictated in part by competitive main chain light absorption, which could be suppressed by using a photoswitching motif that carried most of the frontier molecular orbital densities. Here, we report the modeling and synthesis of a series of thieno[3,4‐<jats:italic>b</jats:italic>]thiophene (TT)‐based photochromes with various aromatic flankers imparting varying degrees of steric bulk and π‐conjugation in order to elucidate the balancing act between steric and electronic factors to promote photochromism. These model systems provide a better understanding of the behavior of photochromic units within extended oligomeric and polymeric π‐conjugated materials.","PeriodicalId":16829,"journal":{"name":"Journal of Physical Organic Chemistry","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141883605","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Theoretical study of atomic electronegativity effects on the excited-state behavior of fluorescent compounds of citrinin","authors":"Yue Gao, Meiheng Lv, Zexu Cai, Yuhang Zhang, Tingting Wang, Jianyong Liu, Fangjian Shang, Wenze Li","doi":"10.1002/poc.4651","DOIUrl":"10.1002/poc.4651","url":null,"abstract":"<p>The present work focuses on the light-induced behavior of citrinin derivatives in relation to atomic electronegativity. A detailed theoretical study on the photophysical properties and excited-state behavior of fluorescent compounds of citrinin (Cit-O, Cit-S, and Cit-Se, with different atomic electronegativity) has been conducted, and the effect of electronegativity on the proton transfer in this system has been explained. First, the relevant hydrogen bond parameters and infrared vibrational spectra of the optimized geometrical configurations have been insightfully investigated. It is elucidated that the hydrogen bond is strengthened after photoexcitation, and it provides a driving force for excited-state intramolecular proton transfer (ESIPT). In addition, the frontier molecular orbitals were analyzed, and the intramolecular charge transfer process in all Cit systems, the phenomenon of charge redistribution, facilitates the ESIPT reaction. By constructing potential energy surfaces for different transfer paths, the atomic electronegativity impact on the ESIPT dynamical behavior of the Cit system was determined. This work clarifies the mechanism of the intramolecular proton transfer process in the excited state of citrinin molecules and complements the theoretical study of the atomic electronegativity-regulated citrinin system, which provides a corresponding theoretical basis for the design and synthesis of new luminescence-adjustable citrinin systems.</p>","PeriodicalId":16829,"journal":{"name":"Journal of Physical Organic Chemistry","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141774711","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Density functional theory study on frustrated Lewis pairs catalyzed C-H activation of heteroarenes: Mechanism variation tuning by electronic effect","authors":"Youxiang Shao, Kang Xiao, Huize Wang, Yalan Liu","doi":"10.1002/poc.4652","DOIUrl":"10.1002/poc.4652","url":null,"abstract":"<p>Unreactive C-H bond activation is a new horizon for frustrated Lewis pairs (FLPs) chemistry. Although concerted mechanism (Science 2015, 349, 513) and stepwise carbene mechanism (Org. Lett. 2018, 20, 1102) have been proposed for the FLPs catalyzed C-H bond activation of 1-methylpyrrole, the influence of electronic properties of FLPs on the reaction mechanism is far away from well-understood. In this study, an assortment of P-B type FLPs with different electronic characteristic was employed to study the catalyzed C-H bond activation of 1-methylpyrrole by using density functional theory calculations. Detailed calculations demonstrated that the reactivity variation and the reaction mechanism binary of FLPs catalyzed C-H activation can be varied by tuning electronic effect of Lewis base center. On the one hand, the concerted C-H activation reactivity is mainly controlled by the electron donation of the lone pair of Lewis base center; thus, the FLPs with electron-donating substituents <b>(FLP1</b>, <b>FLP2</b>, and <b>FLP3)</b> catalyzed the C-H bond activation through concerted mechanism. On the other hand, the reactivity of stepwise carbene mechanism is mostly attributed to the vacant orbital of Lewis acid center; as a result, the <b>FLP5</b> bearing -P(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub> preferred to catalyzed the bond activation through concerted mechanism. In contrast, a metathesis mechanism through strained four-membered ring transition state is less feasible. These results should provide deeper insight and broader perspective to understand the structure and function of FLPs for rational design of FLPs catalyzed C-H bond activation.</p>","PeriodicalId":16829,"journal":{"name":"Journal of Physical Organic Chemistry","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141774712","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Computational comparison of paratropicity trends in antiaromatic s‐indacene derivatives: Does the functional “make all the difference”?","authors":"Michael P. Miller, Michael M. Haley","doi":"10.1002/poc.4648","DOIUrl":"https://doi.org/10.1002/poc.4648","url":null,"abstract":"A recent publication by Wu and co‐workers demonstrated that the workhorse functional B3LYP tends to overemphasize the delocalization in antiaromatic molecules, leading to poor agreement between the calculated proton NMR values and the experimentally obtained numbers. Rather, they showed that the M11 functional affords the best agreement between theory and experiment. We have computationally re‐examined our previously published NICS‐XY scan data using M11‐determined geometries and find that, aside from the placement of s‐indacene, the antiaromaticity trends for both sets of data are essentially identical.","PeriodicalId":16829,"journal":{"name":"Journal of Physical Organic Chemistry","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141642768","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Positive charge delocalization and anti-aromaticity of cations generated by protonation of benzo[a]fluoranthenes in superacid","authors":"Takao Okazaki, Haruki Yamashita, Toshikazu Kitagawa","doi":"10.1002/poc.4647","DOIUrl":"10.1002/poc.4647","url":null,"abstract":"<p>Benzo[<i>a</i>]fluoranthene (<b>4a</b>) is one of non-alternate polycyclic aromatic hydrocarbons. A reaction of <b>4a</b> in CF<sub>3</sub>SO<sub>3</sub>H yielded a dark yellow solution. Direct NMR observation indicated the exclusive formation of carbocation <b>4aH</b><sup><b>+</b></sup> by protonation at the C(8) position. The most deshielded <sup>1</sup>H and <sup>13</sup>C signals were observed at 8.99 ppm for H(12) and 8.29 ppm for H(1), 182.6 ppm for C(12b), 155.6 ppm for C(8a), and 149.4 ppm for C(7a). The signals for H(4) and H(5) were significantly more shielded than those of <b>4a</b>. A reaction of 3-<i>tert</i>-butylbenzo[<i>a</i>]fluoranthene (<b>4b</b>) in CF<sub>3</sub>SO<sub>3</sub>H afforded carbocation <b>4bH</b><sup><b>+</b></sup> by the protonation at the C(8) position. <b>4bH</b><sup><b>+</b></sup> was gradually converted to <b>4aH</b><sup><b>+</b></sup>. The changes in <sup>13</sup>C NMR chemical shifts (Δδ<sup>13</sup>C) suggested that positive charge was delocalized into mainly seven carbons in <b>4aH</b><sup><b>+</b></sup> and <b>4bH</b><sup><b>+</b></sup>. The observed cations were found to be the most stable cations among the possible protonation cations by the DFT method. The NICS(1)<sub><i>zz</i></sub> values for the five-membered rings were calculated to be 35.6 for <b>4aH</b><sup><b>+</b></sup> and 34.4 for <b>4bH</b><sup><b>+</b></sup> by GIAO-B3LYP/6-311+G(2d,p). The experimental NMR and the NICS(1)<sub><i>zz</i></sub> data indicated that the five-membered rings in <b>4aH</b><sup><b>+</b></sup> and <b>4bH</b><sup><b>+</b></sup> exhibited anti-aromaticity.</p>","PeriodicalId":16829,"journal":{"name":"Journal of Physical Organic Chemistry","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141650513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}