PNNP-iridium: A prototypical catalyst framework tailored for diverse hydrogenative depolymerization of polyesters

PNNP-iridium: A prototypical catalyst framework tailored for diverse hydrogenative depolymerization of polyesters | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article PNNP-iridium: A prototypical catalyst framework tailored for diverse hydrogenative depolymerization of polyesters Susumu Saito, Chihaya Murata, Taku Wakabayashi, Naoki Noto, Mineto Uchiyama, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8409046/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract Growing concern over marine- and microplastic pollution has intensified the need for efficient polymer upcycling strategies. Herein, we report a family of iridium complexes bearing a PNNP tetradentate ligand, ((PNNP)Ir), as a versatile prototypical platform for the hydrogenative depolymerization of polyesters. Systematic modification of the bipyridine and phosphine substituents enables the conversion of a broad range of polyesters, including commodity plastics, into diols under mild and even solvent-free conditions. Notably, selective semi-hydrogenation of poly(ethylene terephthalate) (PET) is achieved through fine-tuning of the (PNNP)Ir framework. While fully hydrogenative depolymerization proceeds via direct H₂ addition, semi-hydrogenation operates through a H2-free, transfer-hydrogenation pathway. As a result, (PNNP)Ir complexes can utilize diverse hydrogen sources, and both reaction modes are readily extended to deuteration. These findings establish (PNNP)Ir as an exceptionally versatile and pertinent scaffold for the upcycling of polyesters into value-added chemical feedstocks. Physical sciences/Chemistry/Catalysis/Homogeneous catalysis Physical sciences/Chemistry/Organic chemistry/Synthetic chemistry methodology Physical sciences/Chemistry/Green chemistry/Sustainability Physical sciences/Chemistry/Polymer chemistry/Biopolymers Full Text Additional Declarations There is NO Competing Interest. Supplementary Files SI5Z18.pdf Supporting Information Cite Share Download PDF Status: Under Review Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8409046","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":570852388,"identity":"5861cdfd-7f92-405e-8dfd-11c3923e4d64","order_by":0,"name":"Susumu 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Herein, we report a family of iridium complexes bearing a PNNP tetradentate ligand, ((PNNP)Ir), as a versatile prototypical platform for the hydrogenative depolymerization of polyesters. Systematic modification of the bipyridine and phosphine substituents enables the conversion of a broad range of polyesters, including commodity plastics, into diols under mild and even solvent-free conditions. Notably, selective semi-hydrogenation of poly(ethylene terephthalate) (PET) is achieved through fine-tuning of the (PNNP)Ir framework. While fully hydrogenative depolymerization proceeds via direct H₂ addition, semi-hydrogenation operates through a H2-free, transfer-hydrogenation pathway. As a result, (PNNP)Ir complexes can utilize diverse hydrogen sources, and both reaction modes are readily extended to deuteration. 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