{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T03:26:49Z","timestamp":1760239609080,"version":"build-2065373602"},"reference-count":33,"publisher":"MDPI AG","issue":"23","license":[{"start":{"date-parts":[[2020,12,3]],"date-time":"2020-12-03T00:00:00Z","timestamp":1606953600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["51873185"],"award-info":[{"award-number":["51873185"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>Tenofovir alafenamide (TAF) is a prodrug of tenofovir as a potent nucleotide reverse transcriptase inhibitor. It serves as the key component of Genvoya\u00ae for the first-line treatment of human immunodeficiency virus infection (HIV) and is the active component of Vemlidy\u00ae for the treatment of chronic hepatitis B. Vemlidy\u00ae is also a monotherapeutic regimen formulated as TAF hemifumarate (1; TAF:fumarate = 2:1). In this work, we report for the first time the single-crystal structure of TAF fumarate hemihydrate (2, TAF:fumarate:H2O = 2:2:1). Compound 2 is initially documented as a salt in which one proton of the fumaric acid migrates to the amine group of the adenine moiety in TAF. It was recently proposed that ca. 20\u201330% proton is transferred to the N atom on the aromatic adenine backbone. We herein provide definitive single-crystal X-ray diffraction results to confirm that 2, though phase pure, is formed as a mixture of co-crystal (75%) and salt (25%). It features two pairs of TAF fumarates, wherein one of the four H atoms on the fumaric acid is transferred to the N atom of the adjacent adenine moiety while the other three carboxylates remain in their intrinsic acid form. Compound 2 is a metastable phase during the preparation of 1 and can be isolated by halting the reaction during the refluxing of TAF and fumaric acid in acetonitrile (MeCN). Our report complements the previous characterizations of TAF monofumarate, and its elusive structural patterns are finally deciphered.<\/jats:p>","DOI":"10.3390\/ijms21239213","type":"journal-article","created":{"date-parts":[[2020,12,3]],"date-time":"2020-12-03T11:15:43Z","timestamp":1606994143000},"page":"9213","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["On the Single-Crystal Structure of Tenofovir Alafenamide Mono-Fumarate: A Metastable Phase Featuring a Mixture of Co-Crystal and Salt"],"prefix":"10.3390","volume":"21","author":[{"given":"Jian-Wei","family":"Wang","sequence":"first","affiliation":[{"name":"Department of Chemistry, Zhejiang University, Hangzhou 310028, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lu","family":"Liu","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Zhejiang University, Hangzhou 310028, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ka-Xi","family":"Yu","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Zhejiang University, Hangzhou 310028, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hong-Zhen","family":"Bai","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Zhejiang University, Hangzhou 310028, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jun","family":"Zhou","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Zhejiang University, Hangzhou 310028, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9047-8881","authenticated-orcid":false,"given":"Wen-Hua","family":"Zhang","sequence":"additional","affiliation":[{"name":"College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xiurong","family":"Hu","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Zhejiang University, Hangzhou 310028, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Guping","family":"Tang","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Zhejiang University, Hangzhou 310028, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2020,12,3]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1168","DOI":"10.1126\/science.1193748","article-title":"Effectiveness and safety of tenofovir gel, an antiretroviral microbicide, for the prevention of HIV infection in women","volume":"329","author":"Frohlich","year":"2010","journal-title":"Science"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"307","DOI":"10.1016\/j.ijantimicag.2008.10.010","article-title":"Anti-HIV drugs: 25 compounds approved within 25 years after the discovery of HIV","volume":"33","year":"2009","journal-title":"Int. J. Antimicrob. Agents"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"3191","DOI":"10.1021\/cg100342k","article-title":"New solid state forms of the anti-hiv drug efavirenz. Conformational flexibility and high Z\u2019 issues","volume":"10","author":"Mahapatra","year":"2010","journal-title":"Cryst. Growth Des."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"5909","DOI":"10.1128\/AAC.01152-15","article-title":"In vitro virology profile of tenofovir alafenamide, a novel oral prodrug of tenofovir with improved antiviral activity compared to that of tenofovir disoproxil fumarate","volume":"59","author":"Callebaut","year":"2015","journal-title":"Antimicrob. Agents Chemother."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"2979","DOI":"10.1002\/slct.201600554","article-title":"Counterintuitive solid-state syntheses of indium-thiolate-phen cations as efficient and selective fluorescent biosensors for HIV-1\u2009ds-DNA and Sudan Ebolavirus RNA sequences","volume":"1","author":"Li","year":"2016","journal-title":"ChemistrySelect"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"5092","DOI":"10.1039\/C5DT04410C","article-title":"A zwitterionic 1D\/2D polymer co-crystal and its polymorphic sub-components: A highly selective sensing platform for HIV ds-DNA sequences","volume":"45","author":"Zhao","year":"2016","journal-title":"Dalton Trans."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"12730","DOI":"10.1021\/acs.chemrev.6b00125","article-title":"Retroviral DNA integration","volume":"116","author":"Lesbats","year":"2016","journal-title":"Chem. Rev."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"116","DOI":"10.1016\/j.jconrel.2019.10.045","article-title":"Recent advances on HIV DNA vaccines development: Stepwise improvements to clinical trials","volume":"316","author":"Rezaei","year":"2019","journal-title":"J. Control. Release"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"669","DOI":"10.1177\/135965350601100614","article-title":"Hepatitis B virus replication and liver disease progression: The impact of antiviral therapy","volume":"11","author":"Liaw","year":"2006","journal-title":"Antivir. Ther."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"496","DOI":"10.1086\/655681","article-title":"Systematic review and meta-analysis: Renal safety of tenofovir disoproxil fumarate in HIV-infected patients","volume":"51","author":"Cooper","year":"2010","journal-title":"Clin. Infect. Dis."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"2606","DOI":"10.1016\/S0140-6736(15)60616-X","article-title":"Tenofovir alafenamide versus tenofovir disoproxil fumarate, coformulated with elvitegravir, cobicistat, and emtricitabine, for initial treatment of HIV-1 infection: Two randomised, double-blind, phase 3, non-inferiority trials","volume":"385","author":"Sax","year":"2015","journal-title":"Lancet"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"63","DOI":"10.1016\/j.antiviral.2015.11.009","article-title":"Tenofovir alafenamide: A novel prodrug of tenofovir for the treatment of Human Immunodeficiency Virus","volume":"125","author":"Ray","year":"2016","journal-title":"Antivir. Res."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Lengauer, H., Makuc, D., \u0160terk, D., Perdih, F., Pichler, A., Trdan Lu\u0161in, T., Plavec, J., and \u010casar, Z. (2020). Co-crystals, salts or mixtures of both? The case of tenofovir alafenamide fumarates. Pharmaceutics, 12.","DOI":"10.3390\/pharmaceutics12040342"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"e5146","DOI":"10.1097\/MD.0000000000005146","article-title":"The efficacy and safety of tenofovir alafenamide versus tenofovir disoproxil fumarate in antiretroviral regimens for HIV-1 therapy: Meta-analysis","volume":"95","author":"Wang","year":"2016","journal-title":"Medicine"},{"key":"ref_15","unstructured":"Meng, X. (2019). Crystal Form of Tenofovir Alafenamide Salt, Preparation Method and Use Thereof. (Application No. 10479810), U.S. Patent."},{"key":"ref_16","unstructured":"Han, L., Hu, W., and Wang, H. (2019). Preparing Tenofovir Alafenamide Hemifumarate, Comprises e.g. Reacting Tenofovir and Triphenyl Phosphate, Reacting with Acylating Agent, Amidating with L-alanine Isopropyl Ester, Inducing and Salt Forming with Fumaric Acid in Solvent. (CN110305163-A)."},{"key":"ref_17","unstructured":"Hahn, J., Park, Y.K., Park, S., Kim, C., Shin, S., Choi, W.S., and Gi, K. (2019). New Tenofovir Alafenamide Succinate Salt with Endothermic Peak Measured by Differential Scanning Calorimetry, Useful in Pharmaceutical Composition. (KR2020084713-A)."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"324","DOI":"10.1097\/COH.0000000000000379","article-title":"Candidates for inclusion in a universal antiretroviral regimen: Tenofovir alafenamide","volume":"12","author":"Gotham","year":"2017","journal-title":"Curr. Opin. HIV AIDS"},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Kim, Y.S., Oka, S., Chetchotisakd, P., Clarke, A., Supparatpinyo, K., Avihingsanon, A., Ratanasuwan, W., Kiertiburanakul, S., Ruxrungtham, K., and Yang, S. (2019). Efficacy and safety of elvitegravir\/cobicistat\/emtricitabine\/tenofovir alafenamide in Asian participants with human immunodeficiency virus 1 infection: A sub-analysis of phase 3 clinical trials. HIV Res. Clin. Pract., 1\u20139.","DOI":"10.1080\/15284336.2019.1589232"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"153","DOI":"10.1080\/14787210.2018.1428561","article-title":"Tenofovir alafenamide (TAF) treatment of HBV, what are the unanswered questions?","volume":"16","author":"Loglio","year":"2018","journal-title":"Expert Rev. Anti. Infect. Ther."},{"key":"ref_21","unstructured":"Becker, M.W., Chapman, H.H., Cihlar, T., Eisenberg, E.J., He, G.-X., Kernan, M.R., Lee, W.A., Prisbe, E.J., Rohloff, J.C., and Sparacino, M.L. (2002). Prodrugs of Phosphonate Nucleotide Analogues and Methods for Selecting and Making Same. (Application No. 20020119443 A1), U.S. Patent."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"323","DOI":"10.1021\/mp0601345","article-title":"The salt\u2013cocrystal continuum:\u2009 The influence of crystal structure on ionization state","volume":"4","author":"Childs","year":"2007","journal-title":"Mol. Pharm."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"469","DOI":"10.1016\/j.carres.2009.12.010","article-title":"Metal\u2013carboxylate interactions in metal\u2013alginate complexes studied with FTIR spectroscopy","volume":"345","author":"Papageorgiou","year":"2010","journal-title":"Carbohydr. Res."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"138","DOI":"10.1007\/BF03246512","article-title":"FT-IR, FT-raman and SERS spectra of L-proline","volume":"6","author":"Mary","year":"2009","journal-title":"J. Iran. Chem. Soc."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"6522","DOI":"10.1021\/acs.inorgchem.7b00592","article-title":"Deciphering the structural relationships of five Cd-based metal\u2013organic frameworks","volume":"56","author":"Yuan","year":"2017","journal-title":"Inorg. Chem."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"42978","DOI":"10.1039\/C5RA05564D","article-title":"Isolation of first row transition metal-carboxylate zwitterions","volume":"5","author":"Armaghan","year":"2015","journal-title":"RSC Adv."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"832","DOI":"10.1002\/cplu.202000175","article-title":"Zinc and cadmium complexes of pyridinemethanol carboxylates: Metal carboxylate zwitterions and metal\u2013organic frameworks","volume":"85","author":"Liu","year":"2020","journal-title":"ChemPlusChem"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1231","DOI":"10.1002\/cplu.201500134","article-title":"Metal\u2013organic frameworks via emissive metal-carboxylate zwitterion intermediates","volume":"80","author":"Armaghan","year":"2015","journal-title":"ChemPlusChem"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"19","DOI":"10.1039\/B818330A","article-title":"Hirshfeld surface analysis","volume":"11","author":"Spackman","year":"2009","journal-title":"CrystEngComm"},{"key":"ref_30","unstructured":"Wolff, S., Grimwood, D., McKinnon, J., Turner, M., Jayatilaka, D., and Spackman, M. (2012). Crystal Explorer, The University of Western Australia."},{"key":"ref_31","unstructured":"Higashi, T. (1995). ABSCOR, Rigaku Corporation."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1107\/S2053229614024218","article-title":"Crystal structure refinement with SHELXL","volume":"71","author":"Sheldrick","year":"2015","journal-title":"Acta Crystallogr. Sect. C"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"837","DOI":"10.1107\/S0021889899006020","article-title":"WinGX suite for smallmolecule single-crystal crystallography","volume":"32","author":"Farrugia","year":"1999","journal-title":"J. Appl. Cryst."}],"container-title":["International Journal of Molecular Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1422-0067\/21\/23\/9213\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T10:40:56Z","timestamp":1760179256000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1422-0067\/21\/23\/9213"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,12,3]]},"references-count":33,"journal-issue":{"issue":"23","published-online":{"date-parts":[[2020,12]]}},"alternative-id":["ijms21239213"],"URL":"https:\/\/doi.org\/10.3390\/ijms21239213","relation":{},"ISSN":["1422-0067"],"issn-type":[{"type":"electronic","value":"1422-0067"}],"subject":[],"published":{"date-parts":[[2020,12,3]]}}}