2 research outputs found
Ratiometric Fluorescence Detection of Mercury Ions in Water by Conjugated Polymer Nanoparticles
We present dye-doped polymer nanoparticles that are able
to detect
mercury in aqueous solution at parts per billion levels via fluorescence
resonance energy transfer (FRET). The nanoparticles are prepared by
reprecipitation of highly fluorescent conjugated polymers in water
and are stable in aqueous suspension. They are doped with rhodamine
spirolactam dyes that are nonfluorescent until they encounter mercury
ions, which promote an irreversible reaction that converts the dyes
to fluorescent rhodamines. The rhodamine dyes act as FRET acceptors
for the fluorescent nanoparticles, and the ratio of nanoparticle-to-rhodamine
fluorescence intensities functions as a ratiometric fluorescence chemodosimeter
for mercury. The light harvesting capability of the conjugated polymer
nanoparticles enhances the fluorescence intensity of the rhodamine
dyes by a factor of 10, enabling sensitive detection of mercury ions
in water at levels as low as 0.7 parts per billion
Thermodynamic Control of Isomerizations of Bicyclic Radicals: Interplay of Ring Strain and Radical Stabilization
The
rearrangements of 4-substituted bicyclo[2.2.2]Âoct-5-en-2-yl
radicals, generated from the corresponding Diels–Alder adducts
with phenylseleno acrylates by radical-induced reductive deselenocarbonylations,
give the 2-substituted bicyclo[3.2.1]Âoct-6-en-2-yl radicals with some
substituents, e.g., alkoxy and phenyl, but not for silyloxymethyl
or benzyl substituents. Theoretical calculations with DFT give the
thermodynamics of these reactions and the origins of these processes