title: An NBD-armed thiacalix[4]arene-derived colorimetric and fluorometric chemosensor for Ag+: a metal-ligand receptor of anions.
abstract: A new type of thiacalix[4]arene-based chemosensor 2a and 2b containing amino groups as a binding site and 7-nitrobenzo-2-oxa-1,3-diazole (NBD) as a chromophore have been synthesized and characterized by single crystal X-ray diffraction and by NMR spectroscopic methods. Each receptor acted as a strong colorimetric and fluorometric sensor for silver ions and exhibited significant stepwise deprotonation of NH as evidenced by a bathochromic shift in both the UV-vis absorption and fluorescence emission spectra after addition of an Ag(+) cation. Furthermore, the metal-ligand complex 2a·Ag(+) can be exploited as an ion-pair receptor for the recognition of F(-), AcO(-) or I(-) anions through switching the detection signal output (can been distinguished by 'naked eye'). However, receptor 2b·Ag(+) displays a selective response only to iodide ion. These results could be attributed to the slightly different structural conformation between receptors 2a and 2b, which are derived from a 1,3-alternate-thiacalix[4]arene scaffold, suggesting they play a key role in the selective and binding ability of the host chemosensors.
authors.affiliation: Key Laboratory of Macrocyclic and Supramolecular Chemistry of Guizhou Province, Guizhou University, Guiyang 550025, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Fu
authors.forename: Lan
authors.initials: L
authors.lastname: Mu
authors.forename: Xi
authors.initials: X
authors.lastname: Zeng
authors.forename: Jiang-Lin
authors.initials: JL
authors.lastname: Zhao
authors.forename: Carl
authors.initials: C
authors.lastname: Redshaw
authors.forename: Xin-Long
authors.initials: XL
authors.lastname: Ni
authors.forename: Takehiko
authors.initials: T
authors.lastname: Yamato
mesh_terms: D000838:Anions / Q000737:chemistry; D003124:Colorimetry; D018360:Crystallography, X-Ray; D005470:Fluorometry; D007477:Ions / Q000737:chemistry; D008024:Ligands; D008670:Metals / Q000737:chemistry*; D008968:Molecular Conformation; D010069:Oxadiazoles / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry*; D012834:Silver / Q000032:analysis*; D013440:Sulfides / Q000737:chemistry*
chemical_list: C526864:7-nitrobenz-2-oxa-1,3-diazole; D000838:Anions; D007477:Ions; D008024:Ligands; D008670:Metals; D010069:Oxadiazoles; D010636:Phenols; D013440:Sulfides; C500450:thiacalix(4)arene; D012834:Silver