Fabrication of a novel natural cellulose-based paper chemodosimeter via grafting-to of Rhodamine B moieties for detection of Hg2+

A cellulose-based paper chemodosimeter was designed and prepared by reactions of Rhodamine B with natural cellulose paper. Its sensing property to Hg2+ was investigated by fluorescence spectroscopies. While the Hg2+-indicating paper was immersed into the Hg2+ solution, the ring of the rhodamine spirolactam opened and the thiosemicarbazide moiety would undergo an irreversible desulfurization reaction to form its corresponding oxadiazole structure, a colorful and fluorescent product. The color change can be discerned by a naked eye under the irradiation of 365 nm UV light. The Hg2+-indicating paper displayed excellent selective toward Hg2+ over other commonly metal ions and the sensitive detection of Hg2+ was not interfered by other heavy metal ions. The results suggested that the Hg2+-indicating paper would serve as a practical fluorescent chemodosimeter for rapid and convenience detection of Hg2+.