{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,6]],"date-time":"2026-03-06T02:33:04Z","timestamp":1772764384310,"version":"3.50.1"},"reference-count":53,"publisher":"MDPI AG","issue":"22","license":[{"start":{"date-parts":[[2020,11,13]],"date-time":"2020-11-13T00:00:00Z","timestamp":1605225600000},"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>Seeking to enrich the yet less explored field of scorpionate complexes bearing antioxidant properties, we, here, report on the synthesis, characterization and assessment of the antioxidant activity of new complexes derived from three scorpionate ligands. The interaction between the scorpionate ligands thallium(I) hydrotris(5-methyl-indazolyl)borate (TlTp4Bo,5Me), thallium(I) hydrotris(4,5-dihydro-2H-benzo[g]indazolyl)borate (TlTpa) and potassium hydrotris(3-tert-butyl- pyrazolyl)borate (KTptBu), and metal(II) chlorides, in dichloromethane at room temperature, produced a new family of complexes having the stoichiometric formula [M(Tp4Bo,5Me)2] (M = Cu, 1; Zn, 4; Cd, 7), [M(Tpa)2] (M = Cu, 2; Zn, 5; Cd, 8), [Cu(HpztBu)3Cl2] (3), [Zn(TptBu)Cl] (6) and [Cd(BptBu)(HpztBu)Cl] (9). The obtained metal complexes were characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance and elemental analysis, highlighting the total and partial hydrolysis of the scorpionate ligand TptBu during the synthesis of the Cu(II) complex 3 and the Cd(II) complex 9, respectively. An assessment of the antioxidant activity of the obtained metal complexes was performed through both enzymatic and non-enzymatic assays against 1,1-diphenyl-2-picryl- hydrazyl (DPPH\u00b7), 2,2\u2032-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS+\u00b7), hydroxyl (HO\u00b7), nitric oxide (NO\u00b7), superoxide (O2\u2212) and peroxide (OOH\u00b7) radicals. In particular, the complex [Cu(Tpa)2]\u22c50.5H2O (2) exhibited significant antioxidant activity, as good and specific activity against superoxide (O2\u2212\u00b7), (IC50 values equal to 5.6 \u00b1 0.2 \u03bcM) and might be identified as auspicious SOD-mimics (SOD = superoxide dismutase).<\/jats:p>","DOI":"10.3390\/molecules25225298","type":"journal-article","created":{"date-parts":[[2020,11,13]],"date-time":"2020-11-13T10:32:47Z","timestamp":1605263567000},"page":"5298","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Synthesis, Characterization and Assessment of the Antioxidant Activity of Cu(II), Zn(II) and Cd(II) Complexes Derived from Scorpionate Ligands"],"prefix":"10.3390","volume":"25","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7677-4473","authenticated-orcid":false,"given":"Aurel","family":"T\u0103b\u0103caru","sequence":"first","affiliation":[{"name":"Department of Chemistry, Physics and Environment, Faculty of Sciences and Environment, \u201cDunarea de Jos\u201d University of Galati, 111 Domneasca Street, 800201 Galati, Romania"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7599-8464","authenticated-orcid":false,"given":"Rais Ahmad","family":"Khan","sequence":"additional","affiliation":[{"name":"Department of Chemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Giulio","family":"Lupidi","sequence":"additional","affiliation":[{"name":"School of Pharmacy, University of Camerino, Via S. Agostino 1, 62032 Camerino, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2547-7206","authenticated-orcid":false,"given":"Claudio","family":"Pettinari","sequence":"additional","affiliation":[{"name":"School of Pharmacy, University of Camerino, Via S. Agostino 1, 62032 Camerino, Italy"},{"name":"Istituto di Chimica dei Composti Organometallici (ICCOM-CNR), Via Madonna del Piano 10, 50019 Sesto Fiorentino, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2020,11,13]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1842","DOI":"10.1021\/ja00960a065","article-title":"Boron-pyrazole chemistry","volume":"88","author":"Trofimenko","year":"1966","journal-title":"J. Am. Chem. Soc."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"6288","DOI":"10.1021\/ja01000a053","article-title":"Boron-pyrazole chemistry. II. Poly (1-pyrazolyl)-borates","volume":"89","author":"Trofimenko","year":"1967","journal-title":"J. Am. Chem. Soc."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Trofimenko, S. (1999). Scorpionates: The Coordination Chemistry of Polypyrazolylborate Ligands, Imperial College Press.","DOI":"10.1142\/9781848160422"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"525","DOI":"10.1016\/S0010-8545(04)00131-6","article-title":"Metal derivatives of poly (pyrazolyl) alkanes: I. Tris (pyrazolyl) alkanes and related systems","volume":"249","author":"Pettinari","year":"2005","journal-title":"Coord. Chem. Rev."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"663","DOI":"10.1016\/j.ccr.2004.08.017","article-title":"Metal derivatives of poly (pyrazolyl) alkanes: II. Bis (pyrazolyl) alkanes and related systems","volume":"249","author":"Pettinari","year":"2005","journal-title":"Coord. Chem. Rev."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Pettinari, C. (2008). Scorpionates II: Chelating Borate Ligands, Imperial College Press.","DOI":"10.1142\/9781860948770"},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Pombeiro, A.J.L. (2014). Carbon-scorpionate complexes in oxidation catalysis. Advances in Organometallic Chemistry and Catalysis, the Silver\/Gold Jubilee ICOMC Celebratory Book, John Wiley & Sons.","DOI":"10.1002\/9781118742952"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"2236","DOI":"10.1002\/ejic.201600053","article-title":"Water-soluble C-scorpionate complexes\u2014Catalytic and biological applications","volume":"15\u201316","author":"Martins","year":"2016","journal-title":"Eur. J. Inorg. Chem."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"175","DOI":"10.1016\/bs.adomc.2016.01.002","article-title":"Golden jubilee for scorpionates: Recent advances in organometallic chemistry and their role in catalysis","volume":"Volume 65","year":"2016","journal-title":"Advances in Organometallic Chemistry"},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Martins, L.M.D.R.S. (2017). C-homoscorpionate oxidation catalysts\u2014Electrochemical and catalytic activity. Catalysts, 17.","DOI":"10.3390\/catal7010012"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"89","DOI":"10.1016\/j.ccr.2019.06.009","article-title":"C-scorpionate complexes: Ever young catalytic tools","volume":"396","author":"Martins","year":"2019","journal-title":"Coord. Chem. Rev."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"2377","DOI":"10.1002\/ejic.201501476","article-title":"A family of homo- and heteroscorpionate ligands: Applications to bioinorganic chemistry","volume":"15\u201316","author":"Carrano","year":"2016","journal-title":"Eur. J. Inorg. Chem."},{"key":"ref_13","unstructured":"Gawryszewska, P., and Smole\u0144ski, P. (2014). Synthesis and biological applications of tris (pyrazol-1-yl)-methane and borate metal complexes. Ligands: Synthesis, Characterization and Role in Biotechnology, Nova Science Publishers."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"277","DOI":"10.2174\/157340709789816438","article-title":"Scorpionate complexes suitable for enzyme inhibitor studies","volume":"5","author":"Fischer","year":"2009","journal-title":"Curr. Bioact. Compd."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"45229","DOI":"10.1038\/srep45229","article-title":"Heteroleptic copper (I) complexes of \u201cscorpionate\u201d bis-pyrazolyl carboxylate ligand with auxiliary phosphine as potential anticancer agents: An insight into cytotoxic mode","volume":"7","author":"Khan","year":"2017","journal-title":"Sci. Rep."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"186","DOI":"10.1016\/j.poly.2016.11.040","article-title":"Metal complexes of tridentate tripod ligands in medical imaging and therapy","volume":"125","author":"Silva","year":"2017","journal-title":"Polyhedron"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"875","DOI":"10.1038\/nrc2522","article-title":"Ageing, oxidative stress and cancer: Paradigms in parallax","volume":"8","author":"Benz","year":"2008","journal-title":"Nat. Rev. Cancer"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"1603","DOI":"10.1016\/j.freeradbiomed.2010.09.006","article-title":"Oxidative stress, inflammation, and cancer: How are they linked?","volume":"49","author":"Reuter","year":"2010","journal-title":"Free Radical Biol. Med."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"2703","DOI":"10.2174\/156802611798040741","article-title":"Metal-based antioxidants\u2014Potential therapeutic candidates for prevention the oxidative stress-related carcinogenesis: Mini-review","volume":"11","author":"Milaeva","year":"2011","journal-title":"Curr. Top. Med. Chem."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"2822","DOI":"10.1039\/B407061E","article-title":"Synthesis, characterization and antioxidant activity of new copper (I) complexes of scorpionate and water soluble phosphane ligands","volume":"17","author":"Pellei","year":"2004","journal-title":"Dalton Trans."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"3549","DOI":"10.1016\/j.ica.2004.04.009","article-title":"New (diphenylphosphane) benzoic acid copper (I) derivatives of \u201cscorpionate\u201d ligands with superoxide scavenging activity","volume":"357","author":"Santini","year":"2004","journal-title":"Inorg. Chim. Acta"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"348","DOI":"10.1016\/S0162-0134(03)00028-X","article-title":"Synthesis and characterization of new copper (I) complexes containing 4-(diphenylphosphane) benzoic acid and \u201cscorpionate\u201d ligands with \u201cin vitro\u201d superoxide scavenging activity","volume":"94","author":"Santini","year":"2003","journal-title":"J. Inorg. Biochem."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"820","DOI":"10.1016\/j.jinorgbio.2010.03.013","article-title":"Synthesis, structural and spectroscopic characterization and biomimetic properties of new copper, manganese, zinc complexes: Identification of possible superoxide-dismutase mimics bearing hydroxyl radical generating\/scavenging abilities","volume":"104","author":"Lupidi","year":"2010","journal-title":"J. Inorg. Biochem."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"120","DOI":"10.1016\/j.micpath.2017.05.024","article-title":"Heteroleptic metal (II) complexes of hydrotris (methimazolyl) borate and diimines: Synthesis, theoretical calculations, antimicrobial, antioxidant, in vitro cytotoxicity and molecular docking studies","volume":"109","author":"Jayakumar","year":"2017","journal-title":"Microb. Pathogenesis"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"5097","DOI":"10.1021\/ic970734l","article-title":"Hydrotris (indazolyl) borates: Homoscorpionates with tunable regiochemistry","volume":"36","author":"Rheingold","year":"1997","journal-title":"Inorg. Chem."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"3666","DOI":"10.1021\/ic00095a009","article-title":"Homoscorpionate (tris (pyrazolyl) borate) ligands containing tethered 3-phenyl groups","volume":"33","author":"Rheingold","year":"1994","journal-title":"Inorg. Chem."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1646","DOI":"10.1039\/dt9790001646","article-title":"Single-crystal structure and electronic properties of bis [hydrotris-(pyrazol-1-yl) borato] copper (II)","volume":"11","author":"Murphy","year":"1979","journal-title":"J. Chem. Soc. Dalton Trans."},{"key":"ref_28","first-page":"1092","article-title":"Bis[hydrotris(1-pyrazolyl-N2)borato]zinc(II)","volume":"C51","author":"Nakata","year":"1995","journal-title":"Acta Crystallogr."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"10998","DOI":"10.1021\/ja00149a024","article-title":"113Cd shielding tensors of monomeric cadmium compounds containing nitrogen donor atoms. 3. syntheses, crystal structure, and 113Cd NMR spectroscopy of the six-coordinate complexes [HB (pz)3]2 Cd, [HB(3-Phpz)3]2 Cd, and [B (pz)4] Cd [HB (3-Phpz)3] (pz = pyrazolyl)","volume":"117","author":"Reger","year":"1995","journal-title":"J. Am. Chem. Soc."},{"key":"ref_30","first-page":"1876","article-title":"Structure of bis [hydrotris (3, 5-dimethyl-1-pyrazolyl) borato] copper (II)","volume":"C44","author":"Kitajima","year":"1988","journal-title":"Acta Crystallogr."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1297","DOI":"10.1016\/S0277-5387(96)00423-8","article-title":"Synthesis, characterization and x-ray crystal structure of ZnII complex with poly-nitrogen ligand [\u03b73-HB (3,5-Me2pz)3]2 Zn\u00b72C6H5CH3","volume":"16","author":"Yang","year":"1997","journal-title":"Polyhedron"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"5216","DOI":"10.1021\/ic00075a046","article-title":"Syntheses, structures, 113Cd solution NMR chemical shifts, and investigations of fluxional processes of bis [poly (pyrazolyl) borato] cadmium complexes","volume":"32","author":"Reger","year":"1993","journal-title":"Inorg. Chem."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"C57","DOI":"10.1016\/0022-328X(88)83101-2","article-title":"Unexpected regiochemistry in the reaction of benzotriazole with KBH4: Synthesis of a new class of poly (azolyl) borate ligands","volume":"356","author":"Lalor","year":"1988","journal-title":"J. Organomet. Chem."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"229","DOI":"10.1016\/S0022-328X(00)86105-7","article-title":"Carbonylrhodium (I) derivatives of 3, 5-dimethyl- and 3,5-bis (trifluoromethyl) pyrazole","volume":"218","author":"Banditelli","year":"1981","journal-title":"J. Organomet. Chem."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"11205","DOI":"10.1021\/ic101830e","article-title":"Solid-state 15N CPMAS NMR and computational analysis of ligand hapticity in rhodium (\u03b7-diene) poly (pyrazolyl) borate complexes","volume":"49","author":"Pettinari","year":"2010","journal-title":"Inorg. Chem."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"191","DOI":"10.1016\/S0022-2860(01)00608-1","article-title":"Synthesis, crystal structure and properties of copper (II) complexes with different axial ligands and substituted pyrazoles","volume":"597","author":"Sun","year":"2001","journal-title":"J. Mol. Struct."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"127","DOI":"10.1016\/S0020-1693(02)01178-7","article-title":"An unexpected deboronation of [tBuB (3-tBuC3H2N2)3]\u2212 in a reaction with iron(II) chloride, and the X-ray crystal structure of trans-FeCl2 (tBuC3H3N2)4","volume":"341","author":"Graziani","year":"2002","journal-title":"Inorg. Chim. Acta"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"2820","DOI":"10.1021\/om020930m","article-title":"Synthesis and structural characterization of mixed-sandwich complexes of rhodium (III) and iridium (III) with cyclopentadienyl and hydrotris (pyrazolyl)borate ligands","volume":"22","author":"Carmona","year":"2003","journal-title":"Organometallics"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"m566","DOI":"10.1107\/S0108270107052419","article-title":"Setting ambiguity in C2\/c with dibromidotetrakis (1H-pyrazole -\u03baN2) manganese (II) as an example","volume":"C63","author":"Ruth","year":"2007","journal-title":"Acta Crystalogr."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"2455","DOI":"10.1016\/j.ica.2007.12.015","article-title":"[{Cu (pzPh) (Opo)}2 (\u03bc-Cl)2]: A new dinuclear copper (II) complex with a chloride bridge and mixed blocking ligands","volume":"361","author":"Yraola","year":"2008","journal-title":"Inorg. Chim. Acta"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"4570","DOI":"10.1016\/j.ica.2009.05.065","article-title":"1,2-Borotropic shifts and B\u2013N bond cleavage reactions in molybdenum hydrotris (3-isopropylpyrazolyl) borate chemistry: Mixed-valence MoVIMo2V and pyrazole-rich oxo-MoIV complexes","volume":"362","author":"White","year":"2009","journal-title":"Inorg. Chim. Acta"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"546","DOI":"10.1002\/ejic.201301153","article-title":"Synthesis, characterization, and crystal structures of scorpionate complexes with the hydrotris [3 -(2\u2032-thienyl)pyrazol-1-yl] borate ligand","volume":"2014","author":"Pettinari","year":"2014","journal-title":"Eur. J. Inorg. Chem."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"66","DOI":"10.1016\/j.jphotobiol.2015.11.013","article-title":"Theoretical investigation, biological evaluation and VEGFR2 kinase studies of metal (II) complexes derived from hydrotris (methimazolyl) borate","volume":"155","author":"Jayakumar","year":"2016","journal-title":"J. Photochem. Photobiol. B"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"1559","DOI":"10.1016\/j.ica.2005.10.034","article-title":"Transition metal complexes with pyrazole derivatives as ligands","volume":"359","author":"Bieller","year":"2006","journal-title":"Inorg. Chim. Acta"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"274","DOI":"10.1021\/om00001a041","article-title":"Monomeric alkyl and hydride derivatives of zinc supported by poly(pyrazoly) hydroborato ligation: Synthetic, structural, and reactivity studies","volume":"14","author":"Looney","year":"1995","journal-title":"Organometallics"},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"4345","DOI":"10.1021\/ic00072a030","article-title":"Solid state structures of [hydrotris (3-tert-butyl-5-methylpyrazolyl) borato] chlorotin and -cadmium. Stereochemical influence of a central atom lone pair","volume":"32","author":"Reger","year":"1993","journal-title":"Inorg. Chem."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"155","DOI":"10.1016\/j.jtemb.2004.07.003","article-title":"Antiradical activity of different copper (II) Schiff base complexes and their effect on alloxan-induced diabetes","volume":"18","year":"2004","journal-title":"J. Trace Elem. Med. Biol."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"1507","DOI":"10.1021\/ic00257a010","article-title":"Novel polypyrazolylborate ligands: Coordination control through 3-substituents of the pyrazole ring","volume":"26","author":"Trofimenko","year":"1987","journal-title":"Inorg. Chem."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"284","DOI":"10.1016\/j.jep.2007.06.006","article-title":"Antioxidant activity of Caesalpinia digyna root","volume":"113","author":"Srinivasan","year":"2007","journal-title":"J. Ethnopharmacol."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"1231","DOI":"10.1016\/S0891-5849(98)00315-3","article-title":"Antioxidant activity applying an improved ABTS radical cation decolorization assay","volume":"26","author":"Re","year":"1999","journal-title":"Free Radic. Biol. Med."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"725","DOI":"10.1016\/S0024-3205(99)00643-8","article-title":"Antioxidative and free radical scavenging activities of selected medicinal herbs","volume":"66","author":"Liu","year":"2000","journal-title":"Life Sci."},{"key":"ref_52","first-page":"253","article-title":"An improved method in screening of superoxide and hydroxyl radical scavenging activities of plant medicinal extracts","volume":"32","author":"Kang","year":"2001","journal-title":"Korean J. Pharmacogn."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"785","DOI":"10.1016\/S0039-9140(01)00323-X","article-title":"Detection and determination of nitrate and nitrite: A review","volume":"54","author":"Moorcroft","year":"2001","journal-title":"Talanta"}],"container-title":["Molecules"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1420-3049\/25\/22\/5298\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T10:33:00Z","timestamp":1760178780000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1420-3049\/25\/22\/5298"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,11,13]]},"references-count":53,"journal-issue":{"issue":"22","published-online":{"date-parts":[[2020,11]]}},"alternative-id":["molecules25225298"],"URL":"https:\/\/doi.org\/10.3390\/molecules25225298","relation":{},"ISSN":["1420-3049"],"issn-type":[{"value":"1420-3049","type":"electronic"}],"subject":[],"published":{"date-parts":[[2020,11,13]]}}}