title: An excimer-based, binuclear, on-off switchable calix[4]crown chemosensor.
abstract: A new fluorescent chemosensor with two different types of cation binding sites on the lower rims of a 1,3-alternate calix[4]arene (1) is synthesized. Two pyrene moieties linked to a cation recognition unit composed of two amide groups form a strong excimer in solution. For 1, the excimer fluorescence is quenched by Pb2+, but revived by addition of K+ to the Pb2+ ligand complex. Thus, metal ion exchange produces an on-off switchable, fluorescent chemosensor. Computational results show that the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbitals (LUMO) of the two pyrene moieties interact under UV irradiation of 1 and its K+ complex, while such HOMO-LUMO interactions are absent in the Pb2+ complex.
authors.affiliation: Department of Chemistry, Institute of Nanosensor and Biotechnology, Dankook University, Seoul 140-714, Korea.
authors.forename: Sung Kuk
authors.initials: SK
authors.lastname: Kim
authors.forename: Seoung Ho
authors.initials: SH
authors.lastname: Lee
authors.forename: Ji Yeon
authors.initials: JY
authors.lastname: Lee
authors.forename: Jin Yong
authors.initials: JY
authors.lastname: Lee
authors.forename: Richard A
authors.initials: RA
authors.lastname: Bartsch
authors.forename: Jong Seung
authors.initials: JS
authors.lastname: Kim
mesh_terms: D047250:Calixarenes / Q000138:chemical synthesis / Q000737:chemistry*; D002412:Cations; D005456:Fluorescent Dyes / Q000138:chemical synthesis / Q000737:chemistry*; D007854:Lead / Q000737:chemistry; D008670:Metals / Q000032:analysis / Q000737:chemistry; D008958:Models, Molecular; D010636:Phenols / Q000138:chemical synthesis / Q000737:chemistry*; D011188:Potassium / Q000737:chemistry; D011721:Pyrenes / Q000138:chemical synthesis / Q000737:chemistry; D013050:Spectrometry, Fluorescence
chemical_list: D002412:Cations; D005456:Fluorescent Dyes; D008670:Metals; D010636:Phenols; D011721:Pyrenes; C121325:calix(4)arene; D047250:Calixarenes; D007854:Lead; D011188:Potassium