{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,26]],"date-time":"2025-12-26T05:20:41Z","timestamp":1766726441367,"version":"3.48.0"},"reference-count":54,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2025,12,23]],"date-time":"2025-12-23T00:00:00Z","timestamp":1766448000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>Pyrimethamine (PYR), a drug approved for the treatment of infections caused by protozoan parasites, is a multifunctional API based on 2,4-diaminopyrimidine scaffold. The present study aims toward the development of novel solid forms of PYR, by combining it with three isomeric aminobenzoic acids\u20142-aminobenzoic acid (2NH2-BA), 3-aminobenzoic acid (3NH2-BA), and 4-aminobenzoic acid (4NH2-BA). Solution crystallization led to the formation of three new solvated salts of PYR (PYR\/2NH2-BA\/EtOH\/H2O, PYR\/3NH2-BA\/EtOH, and PYR\/4NH2-BA\/EtOH\/H2O). The detailed physicochemical properties of the formed compounds were characterized by single-crystal X-ray diffraction (SC-XRD), FTIR, PXRD, thermogravimetry (TG), and differential scanning calorimetry (DSC). Additionally, the pre-crystallization solutions of PYR with 2NH2-BA, 3NH2-BA, and 4NH2-BA were studied by electrospray ionization mass spectrometry technique (ESI-MS), which enabled the observation of peaks corresponding to noncovalently bonded molecules, providing insight into their specific aggregation in a solution\/gas phase environment. We identified different non-covalent aggregates, including self-aggregates of aminobenzoic acids and PYR\/aminobenzoic acid associates of different stoichiometries.<\/jats:p>","DOI":"10.3390\/ijms27010180","type":"journal-article","created":{"date-parts":[[2025,12,24]],"date-time":"2025-12-24T09:58:34Z","timestamp":1766570314000},"page":"180","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Salts of Antifolate Pyrimethamine with Isomeric Aminobenzoic Acids: Exploring Packing Interactions and Pre-Crystallization Aggregation"],"prefix":"10.3390","volume":"27","author":[{"given":"Karolina","family":"Cichocka","sequence":"first","affiliation":[{"name":"Faculty of Mathematics and Natural Sciences, Cardinal Stefan Wyszy\u0144ski University, 01-938 Warsaw, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5078-4374","authenticated-orcid":false,"given":"Magdalena","family":"Zimnicka","sequence":"additional","affiliation":[{"name":"Institute of Organic Chemistry, Polish Academy of Sciences, 01-224 Warsaw, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3696-1618","authenticated-orcid":false,"given":"Karolina","family":"K\u0119dra","sequence":"additional","affiliation":[{"name":"Institute of Physical Chemistry, Polish Academy of Sciences, 01-224 Warsaw, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Arkadiusz","family":"Gajek","sequence":"additional","affiliation":[{"name":"Institute of Physical Chemistry, Polish Academy of Sciences, 01-224 Warsaw, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Magdalena","family":"Ceborska","sequence":"additional","affiliation":[{"name":"Faculty of Mathematics and Natural Sciences, Cardinal Stefan Wyszy\u0144ski University, 01-938 Warsaw, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,12,23]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"101531","DOI":"10.1016\/j.jbc.2021.101531","article-title":"The antimicrobial drug pyrimethamine inhibits STAT3 transcriptional activity by targeting the enzyme dihydrofolate reductase","volume":"298","author":"Heppler","year":"2022","journal-title":"J. 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