title: Anthryl-1,2,4-oxadiazole-substituted calix[4]arenes as highly selective fluorescent chemodosimeters for Fe(3+).
abstract: Fluorescent chemosensors 1 and 2, with 1,2,4-oxadiazoles as the binding ligands and anthracene as the fluorophore, were synthesized through sequential 1,3-dipolar cycloaddition reactions of 25,27-dioxyacetonitrilecalix[4]arenes 8 and 11. The fluorescence of 1 was severely quenched by both Fe(3+) and Cu(2+) , whereas that of 2 was selectively quenched only by Fe(3+) . Control compound 4 was also selectively quenched by Fe(3+) , which implied the importance of anthryl-1,2,4-oxadiazole core; furthermore, it was shown to give various oxidation products such as oxanthrone 13, anthraquinone 14, and imidazolyl oxanthrone 15. In addition to product separation and identification, the fluorescent quenching mechanism of these 9-anthryl-1,2,4-oxadiazolyl derivatives by Fe(3+) is also discussed. Furthermore, it should be noted that the oxadiazole-substituted anthracene 4 and calix[4]arene 2 are Fe(3+) -selective fluorescent chemodosimeters without the interference by Cu(2+) .
authors.affiliation: Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan 30050 (P.R. China).
authors.forename: Ying-Jung
authors.initials: YJ
authors.lastname: Chen
authors.forename: Shun-Chieh
authors.initials: SC
authors.lastname: Yang
authors.forename: Chia-Chen
authors.initials: CC
authors.lastname: Tsai
authors.forename: Kai-Chi
authors.initials: KC
authors.lastname: Chang
authors.forename: Wen-Han
authors.initials: WH
authors.lastname: Chuang
authors.forename: Wei-Lun
authors.initials: WL
authors.lastname: Chu
authors.forename: Vladimir
authors.initials: V
authors.lastname: Kovalev
authors.forename: Wen-Sheng
authors.initials: WS
authors.lastname: Chung
keywords: calixarenes; cycloaddition; fluorescence; iron; sensors