{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T04:57:20Z","timestamp":1787029040940,"version":"build-2736575974"},"reference-count":32,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2018,6,29]],"date-time":"2018-06-29T00:00:00Z","timestamp":1530230400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Research Directorate, Vaal University of Technology, Vanderbijlpark Campus, South Africa"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>The current study reports the synthesis of copper complexes of a tridentate Schiff base ligand. The compounds of the type [Cu(L)X]\u2219n(H2O) (where L = tridentate ONN Schiff base ligand, X = Cl\u2212, Br\u2212, SCN\u2212, NO3\u2212, CH3COO\u2212), were characterized on the basis of elemental analyses, FT-IR, UV-vis, molar conductance, 1H-NMR, XRD and thermal analyses. The spectra revealed that the Schiff base ligand acts as a tridentate ligand through two azomethine nitrogen atoms and a phenolic oxygen atom. The molar conductance measurements of the complexes in DMF correspond to non-electrolytic nature. TGA and DTA studies results gave insight into the dehydration, thermal stability, and thermal decomposition. Square-planar geometry has been assigned to the prepared complexes as indicated by the electronic spectral measurements. Cu(II) compounds showed antiradical potential against DPPH and ABTS radicals. The antimicrobial potential of the Schiff base ligand and its Cu(II) complexes were evaluated by the rapid p-iodonitrotetrazolium chloride (INT) colorimetric assay against some selected bacteria strains: Staphylococcus aureus and Enterococcus faecalis (Gram +ve); Klebsiella pneumoniae and Pseudomonas aeruginosa (Gram \u2212ve), and fungi (Candida albicans and Cryptococcus neoformans). The compounds showed a broad spectrum of antibacterial and antifungal activities, with MIC values ranging from 48.83 to 3125 \u03bcg\/mL.<\/jats:p>","DOI":"10.3390\/molecules23071581","type":"journal-article","created":{"date-parts":[[2018,6,29]],"date-time":"2018-06-29T10:51:50Z","timestamp":1530269510000},"page":"1581","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":48,"title":["Cu(II) Complexes of 4-[(1E)-N-{2-[(Z)-Benzylidene-amino]ethyl}ethanimidoyl]benzene-1,3-diol Schiff Base: Synthesis, Spectroscopic, In-Vitro Antioxidant, Antifungal and Antibacterial Studies"],"prefix":"10.3390","volume":"23","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-3643-0198","authenticated-orcid":false,"given":"Ikechukwu P.","family":"Ejidike","sequence":"first","affiliation":[{"name":"Department of Chemistry, Faculty of Applied and Computer Sciences, Vaal University of Technology, P.O. Box X021, Vanderbijlpark 1911, South Africa"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2018,6,29]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"33","DOI":"10.1016\/S0162-0134(00)00214-2","article-title":"Synthesis and characterization of a binuclear coumarin-3-carboxylatecopper(II) complex","volume":"84","author":"Karaliota","year":"2001","journal-title":"J. Inorg. Biochem."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"383","DOI":"10.1016\/j.molstruc.2012.11.030","article-title":"Synthesis, characterization, and antipathogenic studies of some transition metal complexes with N, O-chelating Schiff\u2019s base ligand incorporating azo and sulfonamide Moieties","volume":"1035","author":"Alaghaz","year":"2013","journal-title":"J. Mol. Struct."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1675","DOI":"10.1016\/S0960-894X(01)00266-9","article-title":"Antimycobacterial activity of 9-sulfonylated\/sulfenylated-6-mercaptopurine derivatives","volume":"11","author":"Scozzafava","year":"2001","journal-title":"Bioorg. Med. Chem. Lett."},{"key":"ref_4","first-page":"206417","article-title":"Synthesis, spectroscopic, anticancer, and antimicrobial properties of some metal(II) complexes of (substituted) nitrophenol Schiff base","volume":"2012","author":"Aderoju","year":"2012","journal-title":"Int. J. Inorg. Chem."},{"key":"ref_5","first-page":"180","article-title":"Synthesis and spectroscopic studies of trinuclear N4 Schiff base complexes international","volume":"5","author":"Annapoorani","year":"2013","journal-title":"J. ChemTech Res."},{"key":"ref_6","first-page":"28","article-title":"Synthesis, physical characterization and biological evaluation of Schiff base M(II) complexes","volume":"15","author":"Alias","year":"2014","journal-title":"JAAUBAS"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"63","DOI":"10.4314\/bcse.v29i1.6","article-title":"Synthesis, characterization and antimicrobial activity of some transition metal complexes of N-(5-chloro-2-hydroxyphenyl)-3-methoxy-salicylaldimine","volume":"29","author":"Tavman","year":"2015","journal-title":"Bull. Chem. Soc. Ethiop."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"337","DOI":"10.1016\/j.molstruc.2017.11.022","article-title":"Synthesis, characterization and biological assay of salicylaldehyde Schiff base Cu(II) complexes and their precursors","volume":"1155","author":"Iftikhar","year":"2018","journal-title":"J. Mol. Struct."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"6543","DOI":"10.1007\/s11164-016-2479-x","article-title":"Synthesis and in vitro anticancer, antibacterial, and antioxidant studies of unsymmetrical Schiff base derivatives of 4-[(1E)-N-(2-aminoethyl) ethanimidoyl]benzene-1,3-diol","volume":"42","author":"Ejidike","year":"2016","journal-title":"Res. Chem. Intermed."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"9788","DOI":"10.3390\/molecules20069788","article-title":"Synthesis, characterization and biological studies of metal(II) complexes of (3E)-3-[(2-{(E)-[1-(2,4-Dihydroxyphenyl)ethylidene]amino}ethyl)imino]-1-phenylbutan-1-one Schiff base","volume":"20","author":"Ejidike","year":"2015","journal-title":"Molecules"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"547","DOI":"10.1002\/cjoc.201280004","article-title":"Synthesis, spectral, thermal and biological studies of Mn(II), Co(II), Ni(II) and Cu(II) complexes with 1-(((5-Mercapto-1H-1,2,4-triazol-3-yl)imino)-methyl)naphthalene-2-ol","volume":"30","author":"Issa","year":"2012","journal-title":"Chin. J. Chem."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"4048","DOI":"10.1016\/j.ica.2010.08.009","article-title":"Anticancer and antifungal activity of copper(II) complexes of quinolin-2(1H)-one-derived Schiff bases","volume":"363","author":"Creaven","year":"2010","journal-title":"Inorg. Chim. Acta"},{"key":"ref_13","first-page":"7","article-title":"Synthesis, characterization and DNA interaction studies of Copper(II) complex of 4(3H)-quinazolinone-derived Schiff base","volume":"20","author":"Prasad","year":"2011","journal-title":"An. Univ. Bucuresti Chim."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Ejidike, I.P., and Ajibade, P.A. (2016). Ruthenium(III) complexes of heterocyclic tridentate (ONN) Schiff base: Synthesis, characterization and its biological properties as an antiradical and antiproliferative agent. Int. J. Mol. Sci., 17.","DOI":"10.3390\/ijms17010060"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"8686","DOI":"10.1016\/S1452-3981(23)12919-1","article-title":"Synthesis, spectroscopic characterization and potentiometric studies of a tetradentate [N2O2] Schiff base, N,N\u2032-bis(2-hydroxybenzylidene)-1,1-diaminoethane and Its Co(II), Ni(II), Cu(II) and Zn(II) Complexes","volume":"8","author":"Ammar","year":"2013","journal-title":"Int. J. Electrochem. Sci."},{"key":"ref_16","first-page":"593","article-title":"Synthesis, spectroscopic, antibacterial and free radical scavenging studies of Cu(II), Ni(II), Zn(II) and Co(II) complexes of 4,4\u2032-{ethane-1,2-diylbis[nitrilo(1E)eth-1-yl-1-ylidene]}dibenzene-1,3-diol Schiff base","volume":"9","author":"Ejidike","year":"2017","journal-title":"J. Pharm. Sci. Res."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"81","DOI":"10.1016\/S0010-8545(00)80009-0","article-title":"The use of conductivity measurements in organic solvents for the characterization of coordination compounds","volume":"7","author":"Geary","year":"1971","journal-title":"Coord. Chem. Rev."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"208","DOI":"10.1016\/j.molstruc.2016.12.070","article-title":"Synthesis, structure characterization and biological activity of selected metal complexes of sulfonamide Schiff base as a primary ligand and some mixed ligand complexes with glycine as a secondary ligand","volume":"1134","author":"Sharaby","year":"2017","journal-title":"J. Mol. Struct."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"8629","DOI":"10.3390\/molecules16108629","article-title":"Synthesis, characterization and biological activities of Cu(II), Co(II), Mn(II), Fe(II), and UO2(VI) complexes with a new Schiff base Hydrazone: O-Hydroxyacetophenone-7-chloro-4-quinoline Hydrazone","volume":"16","year":"2011","journal-title":"Molecules"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"483282","DOI":"10.1155\/2014\/483282","article-title":"Synthesis, spectroscopic characterization, and biological evaluation studies of 5-Bromo-3-(((hydroxy-2-methylquinolin-7-yl)methylene)hydrazono) indolin-2-one and its metal(II) complexes","volume":"2014","author":"Siddappa","year":"2014","journal-title":"Bioinorg. Chem. Appl."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"257","DOI":"10.22159\/ijpps.2017v9i12.22225","article-title":"Hydrazide Schiff bases of acetylacetonate metal complexes: Synthesis, spectroscopic and biological studies","volume":"9","author":"Dikio","year":"2017","journal-title":"Int. J. Pharm. Pharm. Sci."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"851","DOI":"10.1016\/j.molstruc.2017.01.036","article-title":"Synthesis, characterization, DFT calculations and biological studies of Mn(II), Fe(II), Co(II) and Cd(II) complexes based on a tetradentate ONNO donor Schiff base ligand","volume":"1134","author":"Ismail","year":"2017","journal-title":"J. Mol. Struct."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"628","DOI":"10.1016\/j.saa.2008.01.023","article-title":"Spectral, XRD, SEM and biological activities of transition metal complexes of polydentate ligands containing thiazole moiety","volume":"71","author":"Neelakantan","year":"2008","journal-title":"Spectrochim. Acta A Mol. Biomol. Spectrosc."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"9672451","DOI":"10.1155\/2016\/9672451","article-title":"Synthesis, characterization, anticancer, and antioxidant studies of Ru(III) complexes of monobasic tridentate Schiff bases","volume":"2016","author":"Ejidike","year":"2016","journal-title":"Bioinorg. Chem. Appl."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Philippopoulos, A.I., Terzis, A., Raptopoulou, C.P., Catalanon, V.J., and Felaras, P. (2007). Synthesis, characterization, and sensitizing properties of heteroleptic RuII complexes based on 2,6-bis(1-pyrazolyl)pyridine and 2,2\u2032-Bipyridine-4,4\u2032-dicarboxylic acid ligands. Eur. J. Inorg. Chem., 5633\u20135644.","DOI":"10.1002\/ejic.200700287"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"36","DOI":"10.1016\/j.molstruc.2014.12.013","article-title":"Synthesis, spectral characterization, molecular modeling and antimicrobial studies of tridentate azo-dye Schiff base metal complexes","volume":"1084","author":"Alaghaz","year":"2015","journal-title":"J. Mol. Struct."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"499","DOI":"10.1081\/SIM-200067062","article-title":"Ruthenium(II) complexes derived from substituted cyclobutane and substituted thiazole Schiff base ligands: Synthetic, spectral, catalytic and antimicrobial studies","volume":"35","author":"Thangadurai","year":"2005","journal-title":"Synth. React. Inorg. Met. Org. Chem."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1121","DOI":"10.3390\/51001121","article-title":"Studies on some acid divalent-metal nitrilotriacetate complexes","volume":"5","author":"Souaya","year":"2000","journal-title":"Molecules"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"195","DOI":"10.1016\/j.arabjc.2010.05.001","article-title":"Synthesis, characterization and biological studies of some Co(II), Ni(II) and Cu(II) complexes derived from indole-3-carboxaldehyde and glycylglycine as Schiff base ligand","volume":"3","author":"Joseyphus","year":"2010","journal-title":"Arab. J. Chem."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Elisha, I.L., Botha, F.S., McGaw, L.J., and Eloff, J.N. (2017). The antibacterial activity of extracts of nine plant species with good activity against Escherichia coli against five other bacteria and cytotoxicity of extracts. BMC Complement. Altern. Med., 17.","DOI":"10.1186\/s12906-017-1645-z"},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Nastas\u0103, C., Vodnar, D.C., Ionu\u0163, I., Stana, A., Benedec, D., Tamaian, R., Oniga, O., and Tiperciuc, B. (2018). Antibacterial evaluation and virtual screening of new Thiazolyl-Triazole Schiff bases as potential DNA-Gyrase inhibitors. Int. J. Mol. Sci., 19.","DOI":"10.3390\/ijms19010222"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"301","DOI":"10.1016\/j.jep.2005.01.061","article-title":"Antifungal activities of six South African Terminalia species (Combretaceae)","volume":"99","author":"Masoko","year":"2005","journal-title":"J. Ethnopharmacol."}],"container-title":["Molecules"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1420-3049\/23\/7\/1581\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T15:10:41Z","timestamp":1760195441000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1420-3049\/23\/7\/1581"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2018,6,29]]},"references-count":32,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2018,7]]}},"alternative-id":["molecules23071581"],"URL":"https:\/\/doi.org\/10.3390\/molecules23071581","relation":{},"ISSN":["1420-3049"],"issn-type":[{"value":"1420-3049","type":"electronic"}],"subject":[],"published":{"date-parts":[[2018,6,29]]}}}