{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,26]],"date-time":"2026-03-26T19:08:45Z","timestamp":1774552125497,"version":"3.50.1"},"reference-count":35,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2007,10,3]],"date-time":"2007-10-03T00:00:00Z","timestamp":1191369600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The synthesis of new fluorescent probes containing the thiophene andbenzoxazole moieties combined with an alanine residue is described. The resulting highlyfluorescent heterocyclic alanine derivatives respond via a quenching effect, withparamagnetic Cu(II) and Ni(II) metal ions and with diamagnetic Hg(II), as shown by theabsorption and steady-state fluorescence spectroscopy studies. The formation ofmononuclear or dinuclear metal complexes was postulated based on the presence of thefree carboxylic acid as binding site and also with the interaction with the donor atoms inthe chromophore. Interaction with other important biological metal ions such as Zn(II),Ca(II) and Na(I) was also explored.<\/jats:p>","DOI":"10.3390\/s7102096","type":"journal-article","created":{"date-parts":[[2008,10,25]],"date-time":"2008-10-25T13:35:40Z","timestamp":1224941740000},"page":"2096-2114","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":49,"title":["Synthesis, Characterization and Metal Ion Detection of Novel Fluoroionophores Based on Heterocyclic Substituted Alanines"],"prefix":"10.3390","volume":"7","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7915-4720","authenticated-orcid":false,"given":"Susana P. G.","family":"Costa","sequence":"first","affiliation":[{"name":"Centro de Qu\u00edmica, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal"}]},{"given":"Elisabete","family":"Oliveira","sequence":"additional","affiliation":[{"name":"REQUIMTE, Faculdade de Ci\u00eancias e Tecnologia, Universidade Nova de Lisboa, 2829-516 Monte de Caparica, Portugal"}]},{"given":"Carlos","family":"Lodeiro","sequence":"additional","affiliation":[{"name":"REQUIMTE, Faculdade de Ci\u00eancias e Tecnologia, Universidade Nova de Lisboa, 2829-516 Monte de Caparica, Portugal"}]},{"given":"M. Manuela M","family":"Raposo","sequence":"additional","affiliation":[{"name":"Centro de Qu\u00edmica, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2007,10,3]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"949 a","DOI":"10.1016\/j.ejmech.2005.03.023","article-title":"Synthesis of some novel benzoxazole derivatives as anticancer, anti-HIV-1 and antimicrobial agents","volume":"40","author":"Rida","year":"2005","journal-title":"Eur. J. Med. Chem."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"2535","DOI":"10.1523\/JNEUROSCI.4456-03.2004","article-title":"Styrylbenzoxazole Derivatives for In Vivo Imaging of Amyloid Plaques in the Brain","volume":"24","author":"Okamura","year":"2004","journal-title":"J. Neurosci."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1349","DOI":"10.1016\/j.tetlet.2004.12.111","article-title":"One-step synthesis of 2-arylbenzothiazole (\u2018BTA\u2019) and -benzoxazole precursors for in vivo imaging of \u03b2-amyloid plaques","volume":"46","author":"Allagile","year":"2005","journal-title":"Tetrahedron Lett."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"358","DOI":"10.1021\/jm050734s","article-title":"Design, Synthesis, and Binding Affinities of Potential Positron Emission Tomography (PET) Ligands for Visualization of Brain Dopamine D3 Receptors","volume":"49","author":"Leopoldo","year":"2006","journal-title":"J. Med. Chem."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"16176","DOI":"10.1021\/bi001230t","article-title":"Polypeptide Modification and Cross-Linking by Oxidized 3-Hydroxykynurenine","volume":"39","author":"Aquilina","year":"2000","journal-title":"Biochemistry"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"15018","DOI":"10.1021\/bi035041x","article-title":"Peptide Ketobenzoxazole Inhibitors Bound to Cathepsin K","volume":"42","author":"McGrath","year":"2003","journal-title":"Biochemistry"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"4399","DOI":"10.1016\/j.bmcl.2004.06.062","article-title":"Stereoselective synthesis and preliminary evaluation of new D-3-heteroarylcarbonylalanines as ligands of the NMDA receptor","volume":"14","author":"Lima","year":"2004","journal-title":"Bioorg. Med. Chem. Lett."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"3588 a","DOI":"10.1016\/j.polymer.2005.03.031","article-title":"Polymerization of cysteine functionalized thiophenes","volume":"46","author":"Cagnoli","year":"2005","journal-title":"Polymer"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"69 a","DOI":"10.1039\/a605031j","article-title":"Optical Chemical Sensors for Pharmaceutical Analysis Using 1,4-Bis(1,3-benzoxazol-2-yl)benzene as Sensing Material","volume":"122","author":"Wang","year":"1997","journal-title":"Analyst"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"712","DOI":"10.1021\/ja039073j","article-title":"Emission Ratiometric Imaging of Intracellular Zinc: Design of a Benzoxazole Fluorescent Sensor and Its Application in Two-Photon Microscopy","volume":"126","author":"Taki","year":"2003","journal-title":"J. Am. Chem. Soc."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"55","DOI":"10.1016\/j.aca.2003.09.008","article-title":"Development of a new fluorimetric bulk optode membrane based on 2,5-thiophenylbis(5-tert-butyl-1,3-benzexazole) for nickel(II) ions","volume":"501","author":"Shamsipur","year":"2004","journal-title":"Anal. Chim. Acta."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"9377","DOI":"10.1016\/j.tetlet.2004.10.115","article-title":"A new fluorescent metal sensor with two binding moieties","volume":"45","author":"Ohshima","year":"2004","journal-title":"Tetrahedron Lett."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"261","DOI":"10.1016\/j.msec.2003.09.020","article-title":"Synthesis of polyhydroxybenzoxazole-based colorimetric chemosensor for anionic species","volume":"24","author":"Lee","year":"2004","journal-title":"Mat. Sci. Eng. C- Bio S."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"11889","DOI":"10.1016\/j.tet.2004.09.084","article-title":"3-[2-(8-Quinolinyl)benzoxazol-5-yl]alanine derivative - a specific fluorophore for transition and rare-earth metal ion detection","volume":"60","author":"Guzow","year":"2004","journal-title":"Tetrahedron"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"947","DOI":"10.1016\/j.inoche.2005.07.008","article-title":"3-[2-(2-Quinoxalinyl)benzoxazol-5-yl]alanine derivative \u2013 A specific fluoroionophore for Ni(II)","volume":"8","author":"Milewska","year":"2005","journal-title":"Inorg. Chem. Commun."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"633","DOI":"10.1016\/j.stam.2005.05.002","article-title":"Photochemical and complexation studies for new fluorescent and colored chelator","volume":"6","author":"Ohshima","year":"2005","journal-title":"Sci. Tech. Adv. Mat."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"189","DOI":"10.1016\/j.aca.2006.03.025","article-title":"A highly selective fluorescent sensor for Cu2+ based on 2-(2\u2032-hydroxyphenyl)benzoxazole in a poly(vinyl chloride) matrix","volume":"567","author":"Zang","year":"2006","journal-title":"Anal. Chim. Acta."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"2825","DOI":"10.1016\/j.tetlet.2004.02.048","article-title":"Synthesis of new fluorescent 2-(2\u2032,2\u2032-bithienyl)-1,3-benzothiazoles","volume":"45","author":"Batista","year":"2004","journal-title":"Tetrahedron Lett."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"3938","DOI":"10.1002\/ejoc.200600059","article-title":"2-Arylthienyl-substituted 1,3-benzothiazoles as new nonlinear optical chromophores","volume":"17","author":"Costa","year":"2006","journal-title":"Eur. J. Org. Chem."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"147","DOI":"10.4028\/www.scientific.net\/MSF.514-516.147","article-title":"New fluorescent heterocyclic materials: synthesis, solvatochromic and fluorescence properties","volume":"514-516","author":"Costa","year":"2006","journal-title":"Mater. Sci. Forum"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"4258","DOI":"10.1016\/j.tet.2007.03.065","article-title":"Synthesis and characterization of new thienylpyrrolyl-benzothiazoles as efficient and thermally stable nonlinear optical chromophores","volume":"63","author":"Batista","year":"2007","journal-title":"Tetrahedron"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"8574","DOI":"10.1021\/jp0730646","article-title":"Spectral and photophysical characterization of donor-\u03c0-acceptor arylthienyl- and bithienyl-benzothiazole derivatives in solution and solid state","volume":"111","author":"Pina","year":"2007","journal-title":"J. Phys. Chem. A."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"9842","DOI":"10.1016\/j.tet.2007.06.098","article-title":"Synthesis and second-order nonlinear optical properties of new chromophores containing benzimidazole, thiophene and pyrrole heterocycles","volume":"63","author":"Batista","year":"2007","journal-title":"Tetrahedron"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"3201","DOI":"10.1021\/ol071029b","article-title":"Synthesis and ion sensing properties of new colorimetric and fluorimetric chemosensors based on bithienyl-imidazo-anthraquinone chromophores","volume":"9","author":"Batista","year":"2007","journal-title":"Org. Lett."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1086 a","DOI":"10.1002\/1522-2675(20010516)84:5<1086::AID-HLCA1086>3.0.CO;2-D","article-title":"Synthesis of a new, highly fluorescent amino acid derivative: N-[(tert-butoxy)carbonyl]-3-[2-(1H-indol-3-yl)benzoxazol-5-yl]-l-alanine methyl ester","volume":"84","author":"Guzow","year":"2001","journal-title":"Helv. Chim. Acta."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Stephens, F. F., and Bower, J. D. The preparation of benziminazoles and benzoxazoles from Schiff's bases. Part I. J. Chem. Soc., 1949, 2971.","DOI":"10.1039\/jr9490002971"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"57","DOI":"10.1016\/j.jphotochem.2005.04.034","article-title":"Influence of substituents in the phenyl ring on photophysical properties of 3-[2-(phenyl)benzoxazol-5-yl]alanine derivatives","volume":"175","author":"Guzow","year":"2005","journal-title":"J. Photochem. Photobiol. A."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Czarnik, A. W. (1993). Fluorescent Chemosensors for Ion and Molecule Recognition, American Chemical Society.","DOI":"10.1021\/bk-1993-0538"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1515","DOI":"10.1021\/cr960386p","article-title":"Signaling Recognition Events with Fluorescent Sensors and Switches","volume":"97","author":"Gunaratne","year":"1997","journal-title":"Chem. Rev."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Valeur, B. (2002). Molecular Fluorescence. Principles and Applications, Wiley-VCH.","DOI":"10.1002\/3527600248"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"2161","DOI":"10.1016\/S1386-1425(01)00492-9","article-title":"Flipping the light switch \u2018ON\u2019 \u2013 the design of sensor molecules that show cation-induced fluorescence enhancement with heavy and transition metal ions","volume":"57","author":"Rurack","year":"2001","journal-title":"Spect. Acta A."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"3533","DOI":"10.1021\/ja00905a001","article-title":"Hard and Soft Acids and Bases","volume":"85","author":"Pearson","year":"1963","journal-title":"J. Am. Chem. Soc."},{"key":"ref_33","unstructured":"SPECFIT\/32 Global Analysis System, 3.0 Spectrum Software Associates."},{"key":"ref_34","unstructured":"Berlman, B. (1971). Handbook of Fluorescence Spectra of Aromatic Molecules, Academic Press. [2nd ed.]."},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Lakowicz, J. R. (1999). Principles of Fluorescence Spectroscopy, Kluwer Academic\/Plenum Publisher. 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