{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,2]],"date-time":"2026-01-02T17:21:00Z","timestamp":1767374460695,"version":"build-2065373602"},"reference-count":34,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2022,8,22]],"date-time":"2022-08-22T00:00:00Z","timestamp":1661126400000},"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, FCT\/MCTES","doi-asserted-by":"publisher","award":["UIDB\/50006\/2020","UIDP\/50006\/2020","ROTEIRO\/0031\/2013\u2014PINFRA\/22161\/2016"],"award-info":[{"award-number":["UIDB\/50006\/2020","UIDP\/50006\/2020","ROTEIRO\/0031\/2013\u2014PINFRA\/22161\/2016"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Chemosensors"],"abstract":"<jats:p>A novel donor-\u03c0-acceptor fluorescent dye as a chemosensor for Cu2+ ions is herein presented. The fluorophoric core consists of a 3,5-diphenyl-dicyanomethylene-4H-pyran (DCM), with extended styryl chains on positions 2 and 6, bearing terminal di-(2-picolyl)amine (DPA) groups for metal coordination. Optical characterization of the chemosensor dye reveals an absorption maximum at ca. 500 nm and a strong bathochromic shift in the emission, reaching ca. 750 nm in polar solvents. This solvatochromic behavior, which yields very large Stokes shifts (up to ~6700 cm\u22121), is characteristic of the strong intramolecular Charge Transfer (CT) nature of this chromophoric system. While the chemosensor has demonstrated no changes in its optical properties over a wide pH range (2\u201312), a strong quenching effect was observed upon Cu2+ coordination, with a 1:1 binding stoichiometry, indicating that only one DPA unit is capable of effectively chelating Cu2+, rendering the second DPA motif inactive. The binding constant was determined to be 7.5 \u00d7 107 M\u22121, indicating a very high sensitivity, and an LOD of 90.1 nM. Competition assays have demonstrated that the chemosensor is highly selective towards Cu2+, even in the presence of excesses of other mono- and di-valent cations. Co2+ and Ni2+ proved to be the strongest interferents, particularly in the luminescent response. Paper test-strips prepared with the embedded sensor showed a fluorometric response in the presence of different copper (II) concentrations, which attested to the potential of this chemosensor to be used in the determination of Cu2+ content in aqueous media, for in-field applications.<\/jats:p>","DOI":"10.3390\/chemosensors10080343","type":"journal-article","created":{"date-parts":[[2022,8,22]],"date-time":"2022-08-22T21:30:34Z","timestamp":1661203834000},"page":"343","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":10,"title":["An NIR Emissive Donor-\u03c0-Acceptor Dicyanomethylene-4H-Pyran Derivative as a Fluorescent Chemosensor System towards Copper (II) Detection"],"prefix":"10.3390","volume":"10","author":[{"given":"Agata","family":"Karkosik","sequence":"first","affiliation":[{"name":"LAQV-REQUIMTE, Departamento de Qu\u00edmica, CQFB, Universidade Nova de Lisboa, Monte de Caparica, 2829-516 Caparica, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3285-4919","authenticated-orcid":false,"given":"Artur J.","family":"Moro","sequence":"additional","affiliation":[{"name":"LAQV-REQUIMTE, Departamento de Qu\u00edmica, CQFB, Universidade Nova de Lisboa, Monte de Caparica, 2829-516 Caparica, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2022,8,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"7105","DOI":"10.1039\/C7CS00240H","article-title":"Fluorescent Chemosensors: The Past, Present and Future","volume":"46","author":"Wu","year":"2017","journal-title":"Chem. 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