{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T03:18:56Z","timestamp":1760239136130,"version":"build-2065373602"},"reference-count":39,"publisher":"MDPI AG","issue":"18","license":[{"start":{"date-parts":[[2020,9,21]],"date-time":"2020-09-21T00:00:00Z","timestamp":1600646400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100004505","name":"Universit\u00e0 di Catania","doi-asserted-by":"publisher","award":["Piano della Ricerca di Ateneo 2016\u20132018, Linea d\u2019intervento 2"],"award-info":[{"award-number":["Piano della Ricerca di Ateneo 2016\u20132018, Linea d\u2019intervento 2"]}],"id":[{"id":"10.13039\/501100004505","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>Rapid and efficient analyses of copper ions are crucial to providing key information for Cu2+ in living cells because of their biological importance. In this study, we reported one new turn-off fluorescent sensor for Cu2+ with a benzo[k,l]xanthene core, which served as an efficient cation sensor for copper ion over a wide range of other cations (Na+, K+, Ag+, Hg2+, Cd2+, Co2+, Ni2+, Zn2+, Mg2+, and Fe3+) owing to the catechol group in the aromatic core. The sensor showed selectivity for Cu2+ over other ions; the logK\u03b2 for Cu2+ binding to compound 1 had a value of 13.265. In the presence of Cu2+, sensor 1 provided significant fluorescence decrement; Co2+, and Ni2+ caused a fluorescence decrement when employed at a higher concentration than Cu2+, while Na+, K+, Hg2+, Cd2+, Zn2+, and Mg2+ metal ions produced only minor changes in fluorescence intensity. Fluorescence experiments demonstrate that compound 1 may have an application as a fluorescent probe for detecting Cu2+ with a limit of detection of 0.574 \u00b5M.<\/jats:p>","DOI":"10.3390\/ijms21186933","type":"journal-article","created":{"date-parts":[[2020,9,21]],"date-time":"2020-09-21T21:01:21Z","timestamp":1600722081000},"page":"6933","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["A Rare Natural Benzo[k,l]xanthene as a Turn-Off Fluorescent Sensor for Cu2+ Ion"],"prefix":"10.3390","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0668-1260","authenticated-orcid":false,"given":"Giuseppe","family":"Floresta","sequence":"first","affiliation":[{"name":"Department of Drug Sciences, University of Catania, Viale A. Doria 6, 95125 Catania, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1480-0861","authenticated-orcid":false,"given":"Nunzio","family":"Cardullo","sequence":"additional","affiliation":[{"name":"Department of Chemical Sciences, University of Catania, Viale A. Doria 6, 95125 Catania, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Carmela","family":"Spatafora","sequence":"additional","affiliation":[{"name":"Department of Chemical Sciences, University of Catania, Viale A. Doria 6, 95125 Catania, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5039-2151","authenticated-orcid":false,"given":"Antonio","family":"Rescifina","sequence":"additional","affiliation":[{"name":"Department of Drug Sciences, University of Catania, Viale A. Doria 6, 95125 Catania, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4268-0115","authenticated-orcid":false,"given":"Corrado","family":"Tringali","sequence":"additional","affiliation":[{"name":"Department of Chemical Sciences, University of Catania, Viale A. Doria 6, 95125 Catania, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2020,9,21]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"855S","DOI":"10.1093\/ajcn\/88.3.855S","article-title":"Role of copper in human neurological disorders","volume":"88","author":"Desai","year":"2008","journal-title":"Am. J. Clin. 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