Citrate-Bound Iron Oxide Clusters in Ionic Liquid Environments: Solvation, Spin-State Energetics, and Bond Dissociation

Citrate-Bound Iron Oxide Clusters in Ionic Liquid Environments: Solvation, Spin-State Energetics, and Bond Dissociation | 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 Research Article Citrate-Bound Iron Oxide Clusters in Ionic Liquid Environments: Solvation, Spin-State Energetics, and Bond Dissociation Leonard Komando, Maciej Bobrowski This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9214951/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 7 You are reading this latest preprint version Abstract The interaction of citrate (C6H5O7 3– ) with kite-like Fe2O3 and tetranuclear Fe4O6 clusters was investigated across seven dielectric environments using unrestricted density functional theory at the UB3LYP-D3(BJ) level with def2-TZVP and 6-31+G(d) basis sets. Implicit solvation was modeled with the SMD continuum for water and the SMD-GIL parametrization for five ionic liquids spanning dielectric constants from 11.4 to 41.0. Citrate coordinates to the Fe2O3 core through a symmetric bidentate carboxylate motif that is preserved across all environments, with Fe–O(citrate) distances of 2.07–2.20 ˚A, while the larger Fe4O6 cluster engages two carboxylate arms simultaneously through shorter monodentate contacts. The antiferromagnetic singlet (S = 0) is the ground state in every environment for the Fe2O3 – Citrate3– complex, whereas one-electron oxidation triggers a magnetic switch to the ferromagnetic dectet (S = 9/2) that is reinforced by dielectric screening. The gas-phase spin-state manifold is compressed to within 5 kcal mol−1 and fans out upon solvation, yet the singlet-to-undecet gap remains nearly constant at 3.2–4.6 kcal mol−1 because the fully ferromagnetic and antiferromagnetic states share similar charge distributions and therefore experience comparable solvation stabilization. Solvation stabilization energies of 307–389 kcal mol−1 reflect the high formal charge of the complex. ZPEcorrected coordination energies decrease from −148 kcal mol−1 in the gas phase to −23 kcal mol−1 in water, with DFT and post-Hartree–Fock methods converging in the condensed phase. Bond dissociation energy curves for the Fe–O(citrate) coordinate reveal well depths of 24–39 kcal mol−1 that decrease monotonically with increasing dielectric constant, and a comparison of single-bond and doublebond scans demonstrates that the bidentate stability originates in the cooperative action of both Fe–O contacts. These results establish the molecular-level foundation for understanding citrate-stabilized iron oxide nanofluids in ionic liquid media. iron oxide clusters citrate coordination ionic liquids spin-state energetics Full Text Additional Declarations No competing interests reported. Supplementary Files structuralchemistrysupplementaryfilled.tex Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 15 Apr, 2026 Reviews received at journal 13 Apr, 2026 Reviewers agreed at journal 01 Apr, 2026 Reviewers invited by journal 29 Mar, 2026 Editor assigned by journal 28 Mar, 2026 Submission checks completed at journal 27 Mar, 2026 First submitted to journal 24 Mar, 2026 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. 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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-9214951","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":615518790,"identity":"33555252-1e5f-4a89-9488-03d9584bd9d4","order_by":0,"name":"Leonard Komando","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABCElEQVRIiWNgGAWjYBACPgjFzCABptkY5MA0D0IKA7ChazGGa2EjVktiA0Et7M3HHvzcY80g2d6d+LmgzCZ9O/8Cxgdv2xjycGrhOZZu2PMsnUGa5+xm6Rnn0nJ3znjAbDi3jaEYpxaJHDMJngOHGeQkcjdI87Ydzt1w4wAbkMGQ2IZLi/wbM8k/EC2bfwO1pBvcOMD+G68WCR4zaZAt0hK520C2JBicb2BjxquFJy1NWuZAOo9kz9lt1jzn0gx3zmBslpxzTgKnX/jZDx+TfHPAWk7ieO/m2zxlNvLm/IcPfnhTZpPHj0MLDPDAWQYS4KiRSCCgAwkY8B8A0yRoGQWjYBSMgmEOAG/HUOhGQ8hSAAAAAElFTkSuQmCC","orcid":"","institution":"Gdańsk University of Technology","correspondingAuthor":true,"prefix":"","firstName":"Leonard","middleName":"","lastName":"Komando","suffix":""},{"id":615518791,"identity":"a434da94-8e21-487c-b318-233a7cf8ba14","order_by":1,"name":"Maciej Bobrowski","email":"","orcid":"","institution":"Gdańsk University of Technology","correspondingAuthor":false,"prefix":"","firstName":"Maciej","middleName":"","lastName":"Bobrowski","suffix":""}],"badges":[],"createdAt":"2026-03-24 17:38:21","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9214951/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9214951/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":105935830,"identity":"4060b9b2-862c-4aaa-8d76-e7eb1b14df22","added_by":"auto","created_at":"2026-04-01 14:58:08","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1521239,"visible":true,"origin":"","legend":"","description":"","filename":"snarticle.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9214951/v1_covered_e0024c8e-eee5-446f-8d12-46c8b9e1e8dd.pdf"},{"id":105935695,"identity":"7f535f7e-a042-4e36-99cc-b42847d9712d","added_by":"auto","created_at":"2026-04-01 14:57:31","extension":"tex","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":23111,"visible":true,"origin":"","legend":"","description":"","filename":"structuralchemistrysupplementaryfilled.tex","url":"https://assets-eu.researchsquare.com/files/rs-9214951/v1/ed4de6c09a55413056216cdc.tex"}],"financialInterests":"No competing interests reported.","formattedTitle":"Citrate-Bound Iron Oxide Clusters in Ionic Liquid Environments: Solvation, Spin-State Energetics, and Bond Dissociation","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"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":"structural-chemistry","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"stuc","sideBox":"Learn more about [Structural Chemistry](https://www.springer.com/journal/11224)","snPcode":"11224","submissionUrl":"https://submission.nature.com/new-submission/11224/3","title":"Structural Chemistry","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"iron oxide clusters, citrate coordination, ionic liquids, spin-state energetics","lastPublishedDoi":"10.21203/rs.3.rs-9214951/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9214951/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe interaction of citrate (C6H5O7 3– ) with kite-like Fe2O3 and tetranuclear Fe4O6 clusters was investigated across seven dielectric environments using unrestricted density functional theory at the UB3LYP-D3(BJ) level with def2-TZVP and 6-31+G(d) basis sets. 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These results establish the molecular-level foundation for understanding citrate-stabilized iron oxide nanofluids in ionic liquid media.\u003c/p\u003e","manuscriptTitle":"Citrate-Bound Iron Oxide Clusters in Ionic Liquid Environments: Solvation, Spin-State Energetics, and Bond Dissociation","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-01 14:55:14","doi":"10.21203/rs.3.rs-9214951/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-04-16T00:32:37+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-13T05:23:31+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"250813297542947274754595736159375981705","date":"2026-04-01T04:49:01+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-29T21:57:17+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-28T07:34:24+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-27T13:02:31+00:00","index":"","fulltext":""},{"type":"submitted","content":"Structural Chemistry","date":"2026-03-24T17:32:19+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"structural-chemistry","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"stuc","sideBox":"Learn more about [Structural Chemistry](https://www.springer.com/journal/11224)","snPcode":"11224","submissionUrl":"https://submission.nature.com/new-submission/11224/3","title":"Structural Chemistry","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"92c88c68-7c7a-4da4-9f71-5d07562cf6d9","owner":[],"postedDate":"April 1st, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-18T21:54:01+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-01 14:55:14","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9214951","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9214951","identity":"rs-9214951","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}