title: Isoquinoline-derivatized tris(2-pyridylmethyl)amines as fluorescent zinc sensors with strict Zn²⁺/Cd²⁺ selectivity.
abstract: Tris(2-pyridylmethyl)amine-based fluorescent ligands, N,N-bis(1-isoquinolylmethyl)-2-pyridylmethylamine (1-isoBQPA) and N,N-bis(7-methoxy-1-isoquinolylmethyl)-2-pyridylmethylamine (7-MeO-1-isoBQPA), have been prepared and the Zn(2+)-induced fluorescence enhancement has been investigated. Upon excitation at 324 nm, 1-isoBQPA exhibits a very weak emission (ϕ = ~0.010) in DMF-H2O (1 : 1). Upon Zn(2+) addition, the 1-isoBQPA fluorescence increases (ϕ(Zn) = 0.055) at 357 nm and 464 nm. The fluorescence enhancement at longer wavelengths is Zn(2+)-specific, whereas Cd(2+) induces a small emission increase at 464 nm (I(Cd)/I0 = 1.1, I(Cd)/I(Zn) = 14%). The Zn(2+)/Cd(2+) selectivity of the fluorescent response correlates with the Cd-N(isoquinoline) and Zn-N(isoquinoline) bond distances measured in the crystal structures. Introduction of methoxy groups into the 1-isoBQPA chromophore enhances the fluorescence significantly (ϕ(Zn) = 0.213), which affords 7-MeO-1-isoBQPA properties amenable for fluorescence microscopy in living cells.
authors.affiliation: KYOUSEI Science Center, Nara Women's University, Nara 630-8506, Japan. mikata@cc.nara-wu.ac.jp.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Mikata
authors.forename: Keiko
authors.initials: K
authors.lastname: Kawata
authors.forename: Saaya
authors.initials: S
authors.lastname: Takeuchi
authors.forename: Kaori
authors.initials: K
authors.lastname: Nakanishi
authors.forename: Hideo
authors.initials: H
authors.lastname: Konno
authors.forename: Saori
authors.initials: S
authors.lastname: Itami
authors.forename: Keiko
authors.initials: K
authors.lastname: Yasuda
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tamotsu
authors.forename: Shawn C
authors.initials: SC
authors.lastname: Burdette
mesh_terms: D002104:Cadmium / Q000032:analysis*; D018360:Crystallography, X-Ray; D005456:Fluorescent Dyes / Q000138:chemical synthesis* / Q000737:chemistry; D007546:Isoquinolines / Q000138:chemical synthesis* / Q000737:chemistry; D008024:Ligands; D008958:Models, Molecular; D015394:Molecular Structure; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence; D015032:Zinc / Q000032:analysis*
chemical_list: D005456:Fluorescent Dyes; D007546:Isoquinolines; D008024:Ligands; D002104:Cadmium; D015032:Zinc