{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,18]],"date-time":"2026-09-18T06:04:49Z","timestamp":1789711489897,"version":"4.0.1"},"reference-count":51,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2015,7,21]],"date-time":"2015-07-21T00:00:00Z","timestamp":1437436800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>In order to compare the coordination properties of 1,4,7-triazacyclononane (tacn) derivatives bearing varying numbers of phosphinic\/carboxylic acid pendant groups towards 68Ga, 1,4,7-triazacyclononane-7-acetic-1,4-bis(methylenephosphinic) acid (NOPA) and 1,4,7- triazacyclononane-4,7-diacetic-1-[methylene(2-carboxyethyl)phosphinic] acid (NO2AP) were synthesized using Mannich reactions with trivalent or pentavalent forms of H-phosphinic acids as phosphorus components. Stepwise protonation constants logK1\u20133 12.06, 3.90 and 1.95, and stability constants with GaIII and CuII, logKGaL 24.01 and logKCuL 16.66, were potentiometrically determined for NOPA. Both ligands were labelled with 68Ga and compared with NOTA (tacn-N,N\u2032,N\u2033-triacetic acid) and NOPO, a TRAP-type [tacn-N,N\u2032,N\u2033- tris(methylenephosphinic acid)] chelator. At pH 3, NOPO and NOPA showed higher labelling efficiency (binding with lower ligand excess) at both room temperature and 95 \u00b0C, compared to NO2AP and NOTA. Labelling efficiency at pH = 0\u20133 correlated with a number of phosphinic acid pendants: NOPO &gt;&gt; NOPA &gt; NO2AP &gt;&gt; NOTA; however, it was more apparent at 95 \u00b0C than at room temperature. By contrast, NOTA was found to be labelled more efficiently at pH &gt; 4 compared to the ligands with phosphinic acids. Overall, replacement of a single phosphinate donor with a carboxylate does not challenge 68Ga labelling of TRAP-type chelators. However, the presence of carboxylates facilitates labelling at neutral or weakly acidic pH.<\/jats:p>","DOI":"10.3390\/molecules200713112","type":"journal-article","created":{"date-parts":[[2015,7,21]],"date-time":"2015-07-21T10:17:48Z","timestamp":1437473868000},"page":"13112-13126","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":21,"title":["The Influence of the Combination of Carboxylate and Phosphinate Pendant Arms in 1,4,7-Triazacyclononane-Based Chelators on Their 68Ga Labelling Properties"],"prefix":"10.3390","volume":"20","author":[{"given":"G\u00e1bor","family":"M\u00e1t\u00e9","sequence":"first","affiliation":[{"name":"Department of Nuclear Medicine, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, H-4032 Debrecen, Hungary"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jakub","family":"\u0160ime\u010dek","sequence":"additional","affiliation":[{"name":"Lehrstuhl f\u00fcr Pharmazeutische Radiochemie, Technische Universit\u00e4t M\u00fcnchen,  Walther-Meissner-Strasse 3, D-85748 Garching, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Miroslav","family":"Pniok","sequence":"additional","affiliation":[{"name":"Department of Inorganic Chemistry, Charles University in Prague, Hlavova 2030, 12840 Prague 2, Czech Republic"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Istv\u00e1n","family":"Kert\u00e9sz","sequence":"additional","affiliation":[{"name":"Department of Nuclear Medicine, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, H-4032 Debrecen, Hungary"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Johannes","family":"Notni","sequence":"additional","affiliation":[{"name":"Lehrstuhl f\u00fcr Pharmazeutische Radiochemie, Technische Universit\u00e4t M\u00fcnchen,  Walther-Meissner-Strasse 3, D-85748 Garching, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hans-J\u00fcrgen","family":"Wester","sequence":"additional","affiliation":[{"name":"Lehrstuhl f\u00fcr Pharmazeutische Radiochemie, Technische Universit\u00e4t M\u00fcnchen,  Walther-Meissner-Strasse 3, D-85748 Garching, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"L\u00e1szl\u00f3","family":"Galuska","sequence":"additional","affiliation":[{"name":"Department of Nuclear Medicine, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, H-4032 Debrecen, Hungary"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Petr","family":"Hermann","sequence":"additional","affiliation":[{"name":"Department of Inorganic Chemistry, Charles University in Prague, Hlavova 2030, 12840 Prague 2, Czech Republic"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2015,7,21]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1113","DOI":"10.2174\/156802610791384243","article-title":"99mTc and 111In-labeling of small biomolecules: Bifunctional chelators and related coordination chemistry","volume":"10","author":"Charkraborty","year":"2010","journal-title":"Curr. 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