Facile synthesis of rhodamine-based highly sensitive and fast responsive colorimetric and off-on fluorescent reversible chemosensors for Hg2+: preparation of a fluorescent thin film sensor

• Published in: Dalton transactions : an international journal of inorganic chemistry 2011-01, Vol.40 (46), p.12578-12583
• Main Authors: Kaewtong, Chatthai, Wanno, Banchob, Uppa, Yuwaporn, Morakot, Nongnit, Pulpoka, Buncha, Tuntulani, Thawatchai
• Format: Article
• Language: English
• Subjects: Amides; Colorimetry; Emission; Mathematical analysis; Polymethyl methacrylates; Rhodamine; Sensors; Thin films
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c1dt11307k

Fluorescence-active chemosensors (L1-L4), comprising a rhodamine scaffold and a pseudo azacrown cation-binding subunit, have been proposed and characterized as a fluorescent chemosensor for Hg(2+). An on-off type fluorescent enhancement was observed by the formation of the ring-opened amide form of the rhodamine moiety, which was induced by the interactions between Hg(2+) and the chemosensor. Upon the addition of Hg(2+), an overall emission change of 350-fold was observed, and the selectivity was calculated to be 300 times higher than Cu(2+) for receptors L2-L4. A polymeric thin film can be obtained by doping poly(methyl methacrylate) or PMMA with chemosensor L2. Such a thin film sensor can be used to detect Hg(2+) with high sensitivity and can be recovered using diluted NaOH.