title: A Novel Ratiometric Fluorescent Mercury Probe Based on Deprotonation-ICT Mechanism.
abstract: A new NBD-rhodamine dye (1) was developed as a colorimetric and ratiometric fluorescent chemosensor for Hg(2+) with good selectivity in aqueous ethanol solutions under neutral to basic conditions. Sensor 1 showed absorption at 468 nm and a weak emission at 529 nm (ϕ F  = 0.063) in ethanol/aqueous tris buffer (9:1, v/v) of pH 9.17 solution. Bathochromic shifts in both absorption (492 nm) and fluorescence spectra (569 nm, ϕ F  = 0.129), respectively upon addition of 2 equiv. of Hg(2+) were observed. The ring-opening reaction of the spirolactam form to the corresponding xanthene form was not found. The interaction of Hg(2+) with chemosensor 1 resulted in the deprotonation of the secondary amine conjugated to the NBD component so that the electron-donating ability of the N atom was enhanced. Deprotonation-ICT mechanism of secondary amines was suggested for the ratiometric fluorescent chemosensing for Hg(2+).
authors.affiliation: College of Sciences, Henan Agricultural University, Zhengzhou, 450002, People's Republic of China. phxie2013@163.com.
authors.forename: Puhui
authors.initials: P
authors.lastname: Xie
authors.affiliation: College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou, 450001, People's Republic of China. fqguo@zzu.edu.cn.
authors.forename: Fengqi
authors.initials: F
authors.lastname: Guo
authors.affiliation: College of Sciences, Henan Agricultural University, Zhengzhou, 450002, People's Republic of China.
authors.forename: Sen
authors.initials: S
authors.lastname: Yang
authors.affiliation: College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou, 450001, People's Republic of China.
authors.forename: Denghui
authors.initials: D
authors.lastname: Yao
authors.affiliation: College of Sciences, Henan Agricultural University, Zhengzhou, 450002, People's Republic of China.
authors.forename: Guoyu
authors.initials: G
authors.lastname: Yang
authors.affiliation: College of Sciences, Henan Agricultural University, Zhengzhou, 450002, People's Republic of China.
authors.forename: Lixia
authors.initials: L
authors.lastname: Xie
mesh_terms: D005456:Fluorescent Dyes / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008628:Mercury / Q000737:chemistry*; D011522:Protons; D013056:Spectrophotometry, Ultraviolet
chemical_list: D005456:Fluorescent Dyes; D011522:Protons; D008628:Mercury
keywords: Chemosensor; Deprotonation-ICT; Fluorescent sensing; Hg2+; NBD-rhodamine dye; Ratiometric sensing