title: Development of a fluorescent chelating ligand for gallium ion having a quinazoline structure with two Schiff base moieties.
abstract: A novel chelating ligand, 2,4-[bis-(2,4-dihydroxybenzylidene)]-dihydrazinoquinazoline (DBHQ), was synthesized, and the fluorescence characteristics of its complex with metal ions were investigated. Thirty-five different metal ions were tested for the emission of fluorescence in the presence of DBHQ in aqueous solutions in a pH range of 3.0-10.5 (at a difference of 0.5 for each metal). It was observed that DBHQ fluoresces intensely at 470nm with an excitation wavelength of 405nm in the presence of Ga(3+) or Al(3+) in the pH range 3.0-4.0. The other metal ions did not show fluorescence with DBHQ. Although the presence of Cu(2+), Co(2+) and Fe(3+) decreased the fluorescence intensity of DBHQ-Ga(3+), the addition of a fluoride ion (NaF) recovered the fluorescence by masking the interfering ions. In addition, the fluoride ions were found to enhance the sensitive determination of Ga(3+) because the fluorescence intensity of DBHQ-Ga(3+) was further increased approximately 2.5-fold in the presence of F(-) (phi=0.658) from that in the absence of F(-) (phi=0.401). The fluoride ions also masked the Al(3+) ions, which emit fluorescence on chelation with DBHQ. Therefore, a selective and sensitive detection of Ga(3+) was achieved by using DBHQ in the presence of F(-). The detection limit of Ga(3+) was approximately 50nmolL(-1) (3.5ppb). The proposed method was applicable to determine Ga(3+) in river water.
authors.affiliation: Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Toho University, 2-2-1 Miyama, Funabashi-shi, Chiba 274-8510, Japan.
authors.forename: Junko
authors.initials: J
authors.lastname: Kimura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yamada
authors.forename: Hayato
authors.initials: H
authors.lastname: Ogura
authors.forename: Takehiko
authors.initials: T
authors.lastname: Yajima
authors.forename: Takeshi
authors.initials: T
authors.lastname: Fukushima
mesh_terms: D001597:Benzylidene Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D002614:Chelating Agents / Q000138:chemical synthesis / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000138:chemical synthesis / Q000737:chemistry*; D005708:Gallium / Q000032:analysis*; D008670:Metals / Q000737:chemistry; D011799:Quinazolines / Q000138:chemical synthesis / Q000737:chemistry*; D045483:Rivers; D012545:Schiff Bases / Q000737:chemistry; D013050:Spectrometry, Fluorescence / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: C539304:2,4-(bis-(2,4-dihydroxybenzylidene))-dihydrazinoquinazoline; D001597:Benzylidene Compounds; D002614:Chelating Agents; D005456:Fluorescent Dyes; D008670:Metals; D011799:Quinazolines; D012545:Schiff Bases; D014874:Water Pollutants, Chemical; D005708:Gallium