Strong Cu(I)–He interaction at open metal sites enables isotope-selective helium adsorption

Strong Cu(I)–He interaction at open metal sites enables isotope-selective helium adsorption | 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 Strong Cu(I)–He interaction at open metal sites enables isotope-selective helium adsorption Thomas Heine, Toshiki Wulf, Shubhajit Das, Elvira Dongmo This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7214188/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 26 Mar, 2026 Read the published version in Nature Communications → Version 1 posted You are reading this latest preprint version Abstract The rare isotope helium-3 (3He) is in very short supply on Earth and highly desired for various applications, including cryogenics, neutron detection and potentially as fuel for nuclear fusion reactors. The main terrestrial resources are tritium decay and the very small fraction in helium-4 dominated supplies obtained from natural gas. This calls for the development of efficient techniques for efficient separation of 3He from isotope mixtures of He gas. In this study, we examine the circumstances that enable the selective adsorption of helium isotopes at open metal sites that commonly occur in metal–organic frameworks (MOFs) and zeolites. To this end, we first focus on small and computationally tractable model complexes of the transition metal Cu(I). We investigate the various aspects of bonding between the metal site and the adsorbed He using couple-cluster methods. In several of our model systems, we observe a substantial difference in adsorption zero-point energy between 3He and 4He, ranging from 0.2 kJ·mol⁻¹ for bare Cu+ to 0.7 kJ·mol⁻¹ for the CuOH complex. For the latter, we predict a remarkable isotope selectivity of adsorption at the technologically relevant temperatures with separation factors of up to 47.2 at 20 K (liquid hydrogen, LH2) and 2.5 at 77 K (liquid nitrogen, LN2). This demonstrates the potential of adsorptive techniques for efficient helium isotope separation at highly attractive open metal sites with a suitable ligand environment. Encouraged by these findings, we expand our investigation to a series of realistic materials of varying complexity, ranging from crown ethers and porphyrins to zeolites and MOFs, as potential hosts for active Cu(I) sites. While all realistic systems exhibit more modest selectivity compared to the simpler model complexes, substantial selectivity approaching a separation factor of 4 is observed at LH2 temperature. Our results emphasize the crucial role of the ligand environment in enhancing selectivity. Among the studied systems, Cu(I) anchored at tetrahedral sites in zeolites and in m502_p3 MOF emerge as particularly promising candidates. Physical sciences/Chemistry/Materials chemistry/Metal–organic frameworks Physical sciences/Chemistry/Theoretical chemistry/Statistical mechanics Full Text Additional Declarations There is NO Competing Interest. Supplementary Files SICuHe20250724.pdf Strong Cu(I)–He interaction at open metal sites enables isotope-selective helium adsorption Cite Share Download PDF Status: Published Journal Publication published 26 Mar, 2026 Read the published version in Nature Communications → 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. 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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-7214188","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":491868887,"identity":"93aa5a56-c67c-477c-8963-d19902588367","order_by":0,"name":"Thomas Heine","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABE0lEQVRIiWNgGAWjYDACCQiVwMAMJD+AmAeAmAfGwAJ4kLUwzkggSQsQMPMQo8Veuvnohh9/GPL42XkPPrb9cZiB7/bhwx/eVNxh4DvegN0WmWNpN3vbGIolm/mSjXMSDjNInktLk5xz5hmD5Bns1vBI5Jjd4G1gSNxwmMdMGqilfsMZHjNm3rbDDAY3EnBqufnnD0Pi/sM85r8tgLYYnOH//Jn3H5Bx/wFOLbd52IC2MAMNZwBr4WGQ5m0A2YLd+zw30tJuy7ZJJM44zGMs2ZOWDvQCm5nknGOHeSTPYHcY+4zkYzff/LFJ7O8/Y/jhh401A98Z5scf3tQcluM7jt37UCCBxX586kfBKBgFo2AU4AcA3dhhNK8cyvMAAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0003-2379-6251","institution":"TU Dresden","correspondingAuthor":true,"prefix":"","firstName":"Thomas","middleName":"","lastName":"Heine","suffix":""},{"id":491868888,"identity":"443f9ae7-89b2-47ec-aac3-021e988a8d53","order_by":1,"name":"Toshiki Wulf","email":"","orcid":"","institution":"University of Leipzig","correspondingAuthor":false,"prefix":"","firstName":"Toshiki","middleName":"","lastName":"Wulf","suffix":""},{"id":491868889,"identity":"e2767d7b-2264-4f0f-9686-1b2f76a1c549","order_by":2,"name":"Shubhajit Das","email":"","orcid":"","institution":"University of Leipzig","correspondingAuthor":false,"prefix":"","firstName":"Shubhajit","middleName":"","lastName":"Das","suffix":""},{"id":491868890,"identity":"20a4e669-82ac-420e-9661-0930197203e8","order_by":3,"name":"Elvira Dongmo","email":"","orcid":"","institution":"HZDR","correspondingAuthor":false,"prefix":"","firstName":"Elvira","middleName":"","lastName":"Dongmo","suffix":""}],"badges":[],"createdAt":"2025-07-25 12:15:34","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7214188/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7214188/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41467-026-70901-6","type":"published","date":"2026-03-26T04:00:00+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":105618275,"identity":"6ea09cd9-ca83-4a88-9799-8653e643f84f","added_by":"auto","created_at":"2026-03-28 07:12:25","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1000340,"visible":true,"origin":"","legend":"","description":"","filename":"CuHe20250724.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7214188/v1_covered_af0fab9e-d15d-4946-928b-860a06148213.pdf"},{"id":88328186,"identity":"7ae7c560-b9b8-49b6-881a-3b707a679d52","added_by":"auto","created_at":"2025-08-05 10:10:35","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":1895701,"visible":true,"origin":"","legend":"Strong Cu(I)\u0026#x2013;He interaction at open metal sites enables isotope-selective helium adsorption","description":"","filename":"SICuHe20250724.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7214188/v1/00e2e5603a7d64c0b6f8e10e.pdf"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Strong Cu(I)–He interaction at open metal sites enables isotope-selective helium adsorption","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"nature-portfolio","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"","title":"Nature Portfolio","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"ejp","reportingPortfolio":"","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-7214188/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7214188/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"The rare isotope helium-3 (3He) is in very short supply on Earth and highly desired for various applications, including cryogenics, neutron detection and potentially as fuel for nuclear fusion reactors. The main terrestrial resources are tritium decay and the very small fraction in helium-4 dominated supplies obtained from natural gas. This calls for the development of efficient techniques for efficient separation of 3He from isotope mixtures of He gas. In this study, we examine the circumstances that enable the selective adsorption of helium isotopes at open metal sites that commonly occur in metal–organic frameworks (MOFs) and zeolites. To this end, we first focus on small and computationally tractable model complexes of the transition metal Cu(I). We investigate the various aspects of bonding between the metal site and the adsorbed He using couple-cluster methods. In several of our model systems, we observe a substantial difference in adsorption zero-point energy between 3He and 4He, ranging from 0.2 kJ·mol⁻¹ for bare Cu+ to 0.7 kJ·mol⁻¹ for the CuOH complex. For the latter, we predict a remarkable isotope selectivity of adsorption at the technologically relevant temperatures with separation factors of up to 47.2 at 20 K (liquid hydrogen, LH2) and 2.5 at 77 K (liquid nitrogen, LN2). This demonstrates the potential of adsorptive techniques for efficient helium isotope separation at highly attractive open metal sites with a suitable ligand environment. Encouraged by these findings, we expand our investigation to a series of realistic materials of varying complexity, ranging from crown ethers and porphyrins to zeolites and MOFs, as potential hosts for active Cu(I) sites. While all realistic systems exhibit more modest selectivity compared to the simpler model complexes, substantial selectivity approaching a separation factor of 4 is observed at LH2 temperature. Our results emphasize the crucial role of the ligand environment in enhancing selectivity. 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