title: Design and synthesis of highly photostable yellow-green emitting 1,8-naphthalimides as fluorescent sensors for metal cations and protons.
abstract: Two highly photostable yellow-green emitting 1,8-naphthalimides 5 and 6, containing both N-linked hindered amine moiety and a secondary or tertiary cation receptor, were synthesized for the first time. Novel compounds were configured as "fluorophore-spacer-receptor" systems based on photoinduced electron transfer. Photophysical characteristics of the dyes were investigated in DMF and water/DMF (4:1, v/v) solution. The ability of the new compounds to detect cations was evaluated by the changes in their fluorescence intensity in the presence of metal ions (Cu2+, Pb2+, Zn2+, Ni2+, Co2+) and protons. The presence of metal ions and protons was found to disallow a photoinduced electron transfer leading to an enhancement in the dye fluorescence intensity. Compound 5, containing secondary amine receptor, displayed a good sensor activity towards metal ions and protons. However the sensor activity of dye 6, containing a tertiary amine receptor and a shorter hydrocarbon spacer, was substantially higher. The results obtained indicate the potential of the novel compounds as highly photostable and efficient "off-on" pH switchers and fluorescent detectors for metal ions with pronounced selectivity towards Cu2+ ions.
authors.affiliation: Department of Organic Synthesis, University of Chemical Technology and Metallurgy, Kliment Ohridsky 8, 1756, Sofia, Bulgaria. vlbojinov@uctm.edu
authors.forename: Vladimir B
authors.initials: VB
authors.lastname: Bojinov
authors.forename: Nikolai I
authors.initials: NI
authors.lastname: Georgiev
authors.forename: Paula
authors.initials: P
authors.lastname: Bosch
mesh_terms: D002412:Cations / Q000032:analysis; D005456:Fluorescent Dyes / Q000138:chemical synthesis* / Q000737:chemistry; D019216:Metals, Heavy / Q000032:analysis*; D015394:Molecular Structure; D053644:Naphthalimides / Q000138:chemical synthesis* / Q000737:chemistry; D010777:Photochemistry; D011522:Protons
chemical_list: D002412:Cations; D005456:Fluorescent Dyes; D019216:Metals, Heavy; D053644:Naphthalimides; D011522:Protons