title: N-(3-Imidazolyl)propyl dansylamide as a selective Hg(2+) sensor in aqueous media through electron transfer.
abstract: N-Imidazolylpropyl dansylamide 1 was synthesized for the sensing of metal ions and found to be selective and sensitive toward Hg(2+) ions in a PBS-EtOH (1:4, pH=7.4) solution. The sensing ability of probe 1 was examined by UV-Vis, fluorescence, and (1)H NMR spectroscopy. The sensing of Hg(2+) exhibited a quenching of emission band at λmax=515 nm of probe 1, which was associated with quenching of green fluorescence emission under 365 nm illumination. Probe 1 showed a good association constant with Hg(2+) (Ka=6.48×10(4) M(-1)) with a stoichiometry of 1:1 in PBS-EtOH (1:4, pH=7.4) having the lowest detection limit of 1 μM for Hg(2+); on the other hand, probe 2, which has no imidazole moiety, was not able to detect any metal ion. In the case of probe 1, electrons on the imidazole nitrogen are available for electron transfer (ET), which was responsible for its green emission band that was quenched on addition of Hg(2+); this clearly indicates that these electrons were used for the formation of a coordinate bond with Hg(2+) and that ET was switched off.
authors.affiliation: Department of Applied Chemistry, School of Applied Chemical Engineering, Kyungpook National University, Daegu 702-701, Republic of Korea.
authors.forename: Ashwani
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Department of Applied Chemistry, School of Applied Chemical Engineering, Kyungpook National University, Daegu 702-701, Republic of Korea. Electronic address: kimhs@knu.ac.kr.
authors.forename: Hong-Seok
authors.initials: HS
authors.lastname: Kim
mesh_terms: D002413:Cations, Divalent / Q000032:analysis; D003619:Dansyl Compounds / Q000737:chemistry*; D004579:Electron Transport; D005456:Fluorescent Dyes / Q000737:chemistry*; D008628:Mercury / Q000032:analysis*; D013050:Spectrometry, Fluorescence; D014867:Water / Q000032:analysis*
chemical_list: D002413:Cations, Divalent; D003619:Dansyl Compounds; D005456:Fluorescent Dyes; D014867:Water; C001026:5-dimethylaminonaphthalene-1-sulfonamide; D008628:Mercury
keywords: Dansylamide; ET; Fluorogenic probe; Hg(2+) ion sensor; Quenching