{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T16:57:43Z","timestamp":1785430663410,"version":"3.56.0"},"reference-count":39,"publisher":"MDPI AG","issue":"14","license":[{"start":{"date-parts":[[2026,7,17]],"date-time":"2026-07-17T00:00:00Z","timestamp":1784246400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan","award":["BR27101179"],"award-info":[{"award-number":["BR27101179"]}]},{"award":["BR27101179"],"award-info":[{"award-number":["BR27101179"]}],"id":[{"id":"https:\/\/ror.org\/05tyne317","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>The structure\u2013activity relationship of three oxyphosphonate inhibitors differing in heteroatom type (C, N, S) was examined to clarify their influence on the pitting corrosion resistance of ferritic\u2013martensitic steel EP-450 in chloride media. Gravimetric tests in 10% FeCl3, supported by surface microscopy and adsorption analysis, showed that EP-450 is highly susceptible to localized attack, with pits nucleating preferentially at carbide-enriched, chromium-depleted regions. Addition of dimethyl(1-hydroxycyclohexyl)phosphonate reduced the corrosion rate from 49 to 33 mm\/year at 2.0 g\/L, corresponding to \u224833% protection, while the nitrogen-containing dimethyl[1-(2-ethoxyethyl)-4-hydroxypiperidin-4-yl]phosphonate produced the largest decrease in mass loss, exceeding a 55% reduction under identical conditions. The sulfur-bearing dimethyl(4-hydroxytetrahydro-2H-thiopyran-4-yl)phosphonate afforded an intermediate effect. Adsorption analysis for the cyclohexyl derivative suggested mixed physisorption\u2013chemisorption with limited surface coverage, while heteroatom substitution (N or S) is consistent with a change in adsorption configuration and interfacial packing that can yield a more compact protective layer. The observed inhibition efficiency increased in the sequence C &lt; S &lt; N, which is interpreted empirically in terms of heteroatom-dependent adsorption geometry and film integrity rather than conjugation-driven activation of the P=O group.<\/jats:p>","DOI":"10.3390\/molecules31142504","type":"journal-article","created":{"date-parts":[[2026,7,20]],"date-time":"2026-07-20T02:32:08Z","timestamp":1784514728000},"page":"2504","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Structure\u2013Activity Relationship of Oxyphosphonate Inhibitors: Role of Heteroatoms in Controlling Pitting Corrosion of Ferritic\u2013Martensitic Steel EP-450"],"prefix":"10.3390","volume":"31","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8884-5646","authenticated-orcid":false,"given":"Tolganay Y.","family":"Zharkynbek","sequence":"first","affiliation":[{"name":"Laboratory of Synthetic and Natural Medicinal Compounds Chemistry, A.B. Bekturov Institute of Chemical Sciences, 106 Sh. Ualikhanov St., Almaty 050010, Kazakhstan"},{"name":"Faculty of Chemistry and Chemical Technology, Al-Farabi Kazakh National University, 71\/23 Al-Farabi Ave., Almaty 050040, Kazakhstan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2575-168X","authenticated-orcid":false,"given":"Dana","family":"Askar","sequence":"additional","affiliation":[{"name":"Laboratory of Synthetic and Natural Medicinal Compounds Chemistry, A.B. Bekturov Institute of Chemical Sciences, 106 Sh. Ualikhanov St., Almaty 050010, Kazakhstan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-8846-7919","authenticated-orcid":false,"given":"Raushan B.","family":"Koizhaiganova","sequence":"additional","affiliation":[{"name":"Laboratory of Synthetic and Natural Medicinal Compounds Chemistry, A.B. Bekturov Institute of Chemical Sciences, 106 Sh. Ualikhanov St., Almaty 050010, Kazakhstan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kira V.","family":"Tsay","sequence":"additional","affiliation":[{"name":"Laboratory of Ion-Plasma Technology, Institute of Nuclear Physics, 1 Ibragimov St., Almaty 050032, Kazakhstan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Khaidar S.","family":"Tassibekov","sequence":"additional","affiliation":[{"name":"Laboratory of Synthetic and Natural Medicinal Compounds Chemistry, A.B. Bekturov Institute of Chemical Sciences, 106 Sh. Ualikhanov St., Almaty 050010, Kazakhstan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0079-4755","authenticated-orcid":false,"given":"Tulegen M.","family":"Seilkhanov","sequence":"additional","affiliation":[{"name":"Laboratory of Engineering Profile NMR Spectroscopy, Sh. Ualikhanov Kokshetau University, 76 Abai St., Kokshetau 020000, Kazakhstan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6713-9080","authenticated-orcid":false,"given":"Ilya G.","family":"Shenderovich","sequence":"additional","affiliation":[{"name":"Faculty of Chemistry and Pharmacy, University of Regensburg, Universitaetstrasse 31, 93053 Regensburg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6508-707X","authenticated-orcid":false,"given":"Valentina K.","family":"Yu","sequence":"additional","affiliation":[{"name":"Laboratory of Synthetic and Natural Medicinal Compounds Chemistry, A.B. Bekturov Institute of Chemical Sciences, 106 Sh. Ualikhanov St., Almaty 050010, Kazakhstan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"156223","DOI":"10.1016\/j.jnucmat.2025.156223","article-title":"Corrosion of EP-450 ferritic\u2013martensitic steel after neutron irradiation and long-term storage in spent fuel pool","volume":"618","author":"Merezhko","year":"2026","journal-title":"J. Nucl. Mater."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"S710","DOI":"10.1016\/j.jnucmat.2013.02.053","article-title":"The role of radiation damage on retention and temperature intervals of helium and hydrogen detrapping in structural materials","volume":"442","author":"Tolstolutskaya","year":"2013","journal-title":"J. Nucl. Mater."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Xu, H., Wang, J., Li, Y., Wang, B., Li, H., and Liu, G. (2024). 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