{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,13]],"date-time":"2026-02-13T04:42:53Z","timestamp":1770957773610,"version":"3.50.1"},"reference-count":44,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2017,11,2]],"date-time":"2017-11-02T00:00:00Z","timestamp":1509580800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>This work reports on a novel fluorescent sensor 1 for Cd2+ ion based on the fluorophore of tetramethyl substituted bis(difluoroboron)-1,2-bis[(1H-pyrrol-2-yl)methylene]hydrazine (Me4BOPHY), which is modified with an electron donor moiety of N,N-bis(pyridin-2-ylmethyl)benzenamine. Sensor 1 has absorption and emission in visible region, at 550 nm and 675 nm, respectively. The long wavelength spectral response makes it easier to fabricate the fluorescence detector. The sensor mechanism is based on the tunable internal charge transfer (ICT) transition of molecule 1. Binding of Cd2+ ion quenches the ICT transition, but turns on the \u03c0 \u2212 \u03c0 transition of the fluorophore, thus enabling ratiometric fluorescence sensing. The limit of detection (LOD) was projected down to 0.77 ppb, which is far below the safety value (3 ppb) set for drinking water by World Health Organization. The sensor also demonstrates a high selectivity towards Cd2+ in comparison to other interferent metal ions.<\/jats:p>","DOI":"10.3390\/s17112517","type":"journal-article","created":{"date-parts":[[2017,11,3]],"date-time":"2017-11-03T04:43:13Z","timestamp":1509684193000},"page":"2517","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":41,"title":["A Ratiometric Fluorescent Sensor for Cd2+ Based on Internal Charge Transfer"],"prefix":"10.3390","volume":"17","author":[{"given":"Dandan","family":"Cheng","sequence":"first","affiliation":[{"name":"Chemical Engineering College, Qinghai University, Xining 810016, China"}]},{"given":"Xingliang","family":"Liu","sequence":"additional","affiliation":[{"name":"Chemical Engineering College, Qinghai University, Xining 810016, China"}]},{"given":"Yadian","family":"Xie","sequence":"additional","affiliation":[{"name":"Chemical Engineering College, Qinghai University, Xining 810016, China"}]},{"given":"Haitang","family":"Lv","sequence":"additional","affiliation":[{"name":"Chemical Engineering College, Qinghai University, Xining 810016, China"}]},{"given":"Zhaoqian","family":"Wang","sequence":"additional","affiliation":[{"name":"Chemical Engineering College, Qinghai University, Xining 810016, China"}]},{"given":"Hongzhi","family":"Yang","sequence":"additional","affiliation":[{"name":"Chemical Engineering College, Qinghai University, Xining 810016, China"}]},{"given":"Aixia","family":"Han","sequence":"additional","affiliation":[{"name":"Chemical Engineering College, Qinghai University, Xining 810016, China"},{"name":"Department of Materials Science and Engineering, University of Utah, Salt Lake City, UT 84108, USA"}]},{"given":"Xiaomei","family":"Yang","sequence":"additional","affiliation":[{"name":"Department of Materials Science and Engineering, University of Utah, Salt Lake City, UT 84108, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4299-0992","authenticated-orcid":false,"given":"Ling","family":"Zang","sequence":"additional","affiliation":[{"name":"Department of Materials Science and Engineering, University of Utah, Salt Lake City, UT 84108, USA"}]}],"member":"1968","published-online":{"date-parts":[[2017,11,2]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"202","DOI":"10.1179\/oeh.2007.13.2.202","article-title":"Cadmium-induced Cancers in Animals and in Humans","volume":"13","author":"Huff","year":"2007","journal-title":"Int. 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