{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,28]],"date-time":"2026-07-28T19:32:07Z","timestamp":1785267127752,"version":"3.55.0"},"reference-count":48,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2022,3,22]],"date-time":"2022-03-22T00:00:00Z","timestamp":1647907200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100018818","name":"National Research, Development and Innovation Office","doi-asserted-by":"publisher","award":["FK124240, K124544 and TKP-2021-EGA-32"],"award-info":[{"award-number":["FK124240, K124544 and TKP-2021-EGA-32"]}],"id":[{"id":"10.13039\/501100018818","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100015498","name":"Ministry for Innovation and Technology","doi-asserted-by":"publisher","award":["\u00daNKP-21-5-SZTE-546 New National Excellence program"],"award-info":[{"award-number":["\u00daNKP-21-5-SZTE-546 New National Excellence program"]}],"id":[{"id":"10.13039\/501100015498","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>The proton dissociation processes of two tridentate salicylidene aminoguanidine Schiff bases (SISC, Pro-SISC-Me), the solution stability and electrochemical properties of their Cu(II), Fe(II) and Fe(III) complexes were characterized using pH-potentiometry, cyclic voltammetry and UV-visible, 1H NMR and electron paramagnetic resonance spectroscopic methods. The structure of the proline derivative (Pro-SISC-Me) was determined by X-ray crystallography. The conjugation of L-proline to the simplest salicylidene aminoguanidine Schiff base (SISC) increased the water solubility due to its zwitterionic structure in a wide pH range. The formation of mono complexes with both ligands was found in the case of Cu(II) and Fe(II), while bis complexes were also formed with Fe(III). In the complexes these tridentate ligands coordinate via the phenolato O, azomethine N and the amidine N, except the complex [Fe(III)L2]+ of Pro-SISC-Me in which the (O,N) donor atoms of the proline moiety are coordinated beside the phenolato O, confirmed by single crystal X-ray crystallographic analysis. This binding mode yielded a stronger Fe(III) preference for Pro-SISC-Me over Fe(II) in comparison to SISC. This finding is also reflected in the lower redox potential value of the iron-Pro-SISC-Me complexes. The ligands alone were not cytotoxic against human colon cancer cell lines, while complexation of SISC with Cu(II) resulted in moderate activity, unlike the case of its more hydrophilic counterpart.<\/jats:p>","DOI":"10.3390\/molecules27072044","type":"journal-article","created":{"date-parts":[[2022,3,22]],"date-time":"2022-03-22T23:30:23Z","timestamp":1647991823000},"page":"2044","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":15,"title":["Solution Equilibrium Studies on Salicylidene Aminoguanidine Schiff Base Metal Complexes: Impact of the Hybridization with L-Proline on Stability, Redox Activity and Cytotoxicity"],"prefix":"10.3390","volume":"27","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8736-3215","authenticated-orcid":false,"given":"Orsolya","family":"D\u00f6m\u00f6t\u00f6r","sequence":"first","affiliation":[{"name":"Department of Inorganic and Analytical Chemistry, Interdisciplinary Excellence Centre, University of Szeged, D\u00f3m t\u00e9r 7, H-6720 Szeged, Hungary"},{"name":"MTA-SZTE Lend\u00fclet Functional Metal Complexes Research Group, University of Szeged, D\u00f3m t\u00e9r 7, H-6720 Szeged, Hungary"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"N\u00f3ra V.","family":"May","sequence":"additional","affiliation":[{"name":"Centre for Structural Science, Research Centre for Natural Sciences, Magyar Tud\u00f3sok K\u00f6r\u00fatja 2, H-1117 Budapest, Hungary"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"G. Tam\u00e1s","family":"G\u00e1l","sequence":"additional","affiliation":[{"name":"Centre for Structural Science, Research Centre for Natural Sciences, Magyar Tud\u00f3sok K\u00f6r\u00fatja 2, H-1117 Budapest, Hungary"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8085-0950","authenticated-orcid":false,"given":"Gabriella","family":"Spengler","sequence":"additional","affiliation":[{"name":"MTA-SZTE Lend\u00fclet Functional Metal Complexes Research Group, University of Szeged, D\u00f3m t\u00e9r 7, H-6720 Szeged, Hungary"},{"name":"Department of Medical Microbiology, Albert Szent-Gy\u00f6rgyi Health Center and Albert Szent-Gy\u00f6rgyi Medical School, University of Szeged, Semmelweis u. 6, H-6725 Szeged, Hungary"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Aliona","family":"Dobrova","sequence":"additional","affiliation":[{"name":"Institute of Inorganic Chemistry, University of Vienna, W\u00e4hringer Strasse 42, A-1090 Vienna, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1895-6460","authenticated-orcid":false,"given":"Vladimir B.","family":"Arion","sequence":"additional","affiliation":[{"name":"Institute of Inorganic Chemistry, University of Vienna, W\u00e4hringer Strasse 42, A-1090 Vienna, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8058-8128","authenticated-orcid":false,"given":"\u00c9va A.","family":"Enyedy","sequence":"additional","affiliation":[{"name":"Department of Inorganic and Analytical Chemistry, Interdisciplinary Excellence Centre, University of Szeged, D\u00f3m t\u00e9r 7, H-6720 Szeged, Hungary"},{"name":"MTA-SZTE Lend\u00fclet Functional Metal Complexes Research Group, University of Szeged, D\u00f3m t\u00e9r 7, H-6720 Szeged, Hungary"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2022,3,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"31","DOI":"10.1016\/j.abb.2003.08.013","article-title":"Use of aminoguanidine (Pimagedine) to prevent the formation of advanced glycation endproducts","volume":"419","author":"Thornalley","year":"2003","journal-title":"Arch. 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