{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,30]],"date-time":"2025-11-30T09:17:45Z","timestamp":1764494265047,"version":"build-2065373602"},"reference-count":41,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2023,4,9]],"date-time":"2023-04-09T00:00:00Z","timestamp":1680998400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e Tecnologia\u2014FCT (Portugal)","doi-asserted-by":"publisher","award":["UIDB\/00686\/2020","2020.05277.BD","REDE\/1517\/RMN\/2005"],"award-info":[{"award-number":["UIDB\/00686\/2020","2020.05277.BD","REDE\/1517\/RMN\/2005"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"name":"POCI 2010 (FEDER)","award":["UIDB\/00686\/2020","2020.05277.BD","REDE\/1517\/RMN\/2005"],"award-info":[{"award-number":["UIDB\/00686\/2020","2020.05277.BD","REDE\/1517\/RMN\/2005"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Unnatural amino acids with enhanced properties, such as increased complexing ability and luminescence, are considered to be highly attractive building blocks for bioinspired frameworks, such as probes for biomolecule dynamics, sensitive fluorescent chemosensors, and peptides for molecular imaging, among others. Therefore, a novel series of highly emissive heterocyclic alanines bearing a benzo[d]oxazolyl unit functionalized with different heterocyclic \u03c0-spacers and (aza)crown ether moieties was synthesized. The new compounds were completely characterized using the usual spectroscopic techniques and evaluated as fluorimetric chemosensors in acetonitrile and aqueous mixtures in the presence of various alkaline, alkaline-earth, and transition metal ions. The different crown ether binding moieties as well as the electronic nature of the \u03c0-bridge allowed for fine tuning of the sensory properties of these unnatural amino acids towards Pd2+ and Fe3+, as seen by spectrofluorimetric titrations.<\/jats:p>","DOI":"10.3390\/molecules28083326","type":"journal-article","created":{"date-parts":[[2023,4,10]],"date-time":"2023-04-10T03:24:18Z","timestamp":1681097058000},"page":"3326","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":11,"title":["Novel Crown Ether Amino Acids as Fluorescent Reporters for Metal Ions"],"prefix":"10.3390","volume":"28","author":[{"given":"Patr\u00edcia M. R.","family":"Batista","sequence":"first","affiliation":[{"name":"Centre of Chemistry, Campus de Gualtar, University of Minho, 4710-057 Braga, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6316-864X","authenticated-orcid":false,"given":"C\u00e1tia D. F.","family":"Martins","sequence":"additional","affiliation":[{"name":"Centre of Chemistry, Campus de Gualtar, University of Minho, 4710-057 Braga, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7996-1626","authenticated-orcid":false,"given":"M. Manuela M.","family":"Raposo","sequence":"additional","affiliation":[{"name":"Centre of Chemistry, Campus de Gualtar, University of Minho, 4710-057 Braga, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7915-4720","authenticated-orcid":false,"given":"Susana P. G.","family":"Costa","sequence":"additional","affiliation":[{"name":"Centre of Chemistry, Campus de Gualtar, University of Minho, 4710-057 Braga, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2023,4,9]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"2200195","DOI":"10.1002\/marc.202200195","article-title":"Chemical modification for the \u201cOff-\/On\u201d regulation of enzyme activity","volume":"43","author":"Yu","year":"2022","journal-title":"Macromol. Rap. Commun."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Yamawaki, Y., Yufu, T., and Kato, T. (2021). The effect of a peptide substrate containing an unnatural branched amino acid on chymotrypsin activity. 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