title: Synthesis and characterization of zinc sensors based on a monosubstituted fluorescein platform.
abstract: The synthesis of a new fluorescein carboxaldehyde asymmetrically substituted on the xanthene (top) ring is reported. This molecule is a key precursor for two of three monofunctionally derivatized fluorescein-based Zn(II) sensors presented in this work. Detailed preparative routes to, and photophysical characterization of, these sensors are described. The sensors are based on the previously reported ZP4 motif (Burdette, S. C.; Frederickson, C. J.; Bu, W.; Lippard, S. J. J. Am. Chem. Soc. 2003, 125, 1778-1787) and incorporate a di(2-picolyl)amine-containing aniline-derivatized ligand framework. By varying the nature of the substituent (X) para to the aniline nitrogen atom, which is responsible for PET quenching of the unbound ZP dye, we investigated the extent to which such electronic tuning might improve the fluorescent properties of asymmetrical ZP sensors. Although a comparison of probes with X = H, F, Cl, OMe reveals that the photophysical behavior of these dyes is not readily predictable, our methodology illustrates the ease with which aniline-based ligands may be linked to fluorescein dyes.
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Nolan
authors.forename: Shawn C
authors.initials: SC
authors.lastname: Burdette
authors.forename: Jessica H
authors.initials: JH
authors.lastname: Harvey
authors.forename: Scott A
authors.initials: SA
authors.lastname: Hilderbrand
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Lippard
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D018360:Crystallography, X-Ray; D005452:Fluoresceins / Q000138:chemical synthesis* / Q000737:chemistry; D005456:Fluorescent Dyes / Q000138:chemical synthesis* / Q000737:chemistry; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D013056:Spectrophotometry, Ultraviolet; D014966:Xanthenes / Q000737:chemistry; D015032:Zinc / Q000737:chemistry*
chemical_list: D005452:Fluoresceins; D005456:Fluorescent Dyes; D014966:Xanthenes; D015032:Zinc