{"title":"两步机制的机械化学逆-Diels-Alder-异构体自由基稳定?","authors":"Hang Zhang, Charles E. Diesendruck","doi":"10.1021/acs.macromol.5c00084","DOIUrl":null,"url":null,"abstract":"In organic molecules, heteroatom substitutions are a powerful molecular engineering strategy for modulating chemical reactivity. This is particularly interesting in polymer mechanochemistry, in which the reaction mechanism can change due to the force modification of the potential energy surface of mechanophores. Here, we investigate the effects of inserting a single heteroatom (N, O, and S) next to the bridging carbon of anthracene–maleimide (AnM) adduct mechanophores. It has been previously proposed that upon application of force, the reaction mechanism changes from concerted to a two-step mechanism based on homolytic bond scission, and therefore, such heteroatoms could affect this conversion. Indeed, the mechanochemistry experiments revealed a meaningful acceleration in force-induced retro-Diels–Alder reaction. Notably, sulfur atom insertion resulted in the highest enhancement in reactivity, with a ca. 2-fold increase compared to a carbon atom at the same position. Computational studies reveal that a simplistic look based on transition state theory does not explain such enhanced reactivity, and therefore, ab initio steered molecular dynamics are used, indicating that the radical lifetime after bond scission correlates well with the experimental results. Importantly, both experimental and computational data confirm that heteroatom insertion is an effective and practical approach to enhancing mechanophore reactivity.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"58 1","pages":""},"PeriodicalIF":5.2000,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Mechanochemical Retro-Diels–Alder–Heteroatom Radical Stabilization of a Two-Step Mechanism?\",\"authors\":\"Hang Zhang, Charles E. Diesendruck\",\"doi\":\"10.1021/acs.macromol.5c00084\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"In organic molecules, heteroatom substitutions are a powerful molecular engineering strategy for modulating chemical reactivity. This is particularly interesting in polymer mechanochemistry, in which the reaction mechanism can change due to the force modification of the potential energy surface of mechanophores. Here, we investigate the effects of inserting a single heteroatom (N, O, and S) next to the bridging carbon of anthracene–maleimide (AnM) adduct mechanophores. It has been previously proposed that upon application of force, the reaction mechanism changes from concerted to a two-step mechanism based on homolytic bond scission, and therefore, such heteroatoms could affect this conversion. Indeed, the mechanochemistry experiments revealed a meaningful acceleration in force-induced retro-Diels–Alder reaction. Notably, sulfur atom insertion resulted in the highest enhancement in reactivity, with a ca. 2-fold increase compared to a carbon atom at the same position. Computational studies reveal that a simplistic look based on transition state theory does not explain such enhanced reactivity, and therefore, ab initio steered molecular dynamics are used, indicating that the radical lifetime after bond scission correlates well with the experimental results. Importantly, both experimental and computational data confirm that heteroatom insertion is an effective and practical approach to enhancing mechanophore reactivity.\",\"PeriodicalId\":51,\"journal\":{\"name\":\"Macromolecules\",\"volume\":\"58 1\",\"pages\":\"\"},\"PeriodicalIF\":5.2000,\"publicationDate\":\"2025-04-15\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Macromolecules\",\"FirstCategoryId\":\"92\",\"ListUrlMain\":\"https://doi.org/10.1021/acs.macromol.5c00084\",\"RegionNum\":1,\"RegionCategory\":\"化学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"POLYMER SCIENCE\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Macromolecules","FirstCategoryId":"92","ListUrlMain":"https://doi.org/10.1021/acs.macromol.5c00084","RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"POLYMER SCIENCE","Score":null,"Total":0}
Mechanochemical Retro-Diels–Alder–Heteroatom Radical Stabilization of a Two-Step Mechanism?
In organic molecules, heteroatom substitutions are a powerful molecular engineering strategy for modulating chemical reactivity. This is particularly interesting in polymer mechanochemistry, in which the reaction mechanism can change due to the force modification of the potential energy surface of mechanophores. Here, we investigate the effects of inserting a single heteroatom (N, O, and S) next to the bridging carbon of anthracene–maleimide (AnM) adduct mechanophores. It has been previously proposed that upon application of force, the reaction mechanism changes from concerted to a two-step mechanism based on homolytic bond scission, and therefore, such heteroatoms could affect this conversion. Indeed, the mechanochemistry experiments revealed a meaningful acceleration in force-induced retro-Diels–Alder reaction. Notably, sulfur atom insertion resulted in the highest enhancement in reactivity, with a ca. 2-fold increase compared to a carbon atom at the same position. Computational studies reveal that a simplistic look based on transition state theory does not explain such enhanced reactivity, and therefore, ab initio steered molecular dynamics are used, indicating that the radical lifetime after bond scission correlates well with the experimental results. Importantly, both experimental and computational data confirm that heteroatom insertion is an effective and practical approach to enhancing mechanophore reactivity.
期刊介绍:
Macromolecules publishes original, fundamental, and impactful research on all aspects of polymer science. Topics of interest include synthesis (e.g., controlled polymerizations, polymerization catalysis, post polymerization modification, new monomer structures and polymer architectures, and polymerization mechanisms/kinetics analysis); phase behavior, thermodynamics, dynamic, and ordering/disordering phenomena (e.g., self-assembly, gelation, crystallization, solution/melt/solid-state characteristics); structure and properties (e.g., mechanical and rheological properties, surface/interfacial characteristics, electronic and transport properties); new state of the art characterization (e.g., spectroscopy, scattering, microscopy, rheology), simulation (e.g., Monte Carlo, molecular dynamics, multi-scale/coarse-grained modeling), and theoretical methods. Renewable/sustainable polymers, polymer networks, responsive polymers, electro-, magneto- and opto-active macromolecules, inorganic polymers, charge-transporting polymers (ion-containing, semiconducting, and conducting), nanostructured polymers, and polymer composites are also of interest. Typical papers published in Macromolecules showcase important and innovative concepts, experimental methods/observations, and theoretical/computational approaches that demonstrate a fundamental advance in the understanding of polymers.