Optically-Based Array Sensors for Selective In Situ Analysis of Tank Waste Page: 3 of 4
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The emission of I in a CH2Cl2:MeOH mixture (1:1) is only slightly affected by the
presence of either Li' or Na' ions at concentrations as high as 0.1 M ruling out the
possibility of strong complexation of these ions by I. In the presence of K+ ions, the
emission of I experiences a slight enhancement. The most dramatic change in the emission
of I is observed in the presence of Cs+ ions (11.7 fold increase in the emission). The
association constants Ki and K12 (for the first and second metal ion complexation)
determined from fluorescence data suggest 1:2 stoichiometery for I : Cs+ in good
agreement with the reported values for other systems that accommodate two metal ions at
the complexing sites.
Two derivatives of alkylanthracene covalently bonded to 1,3-alternate calix[4]-diaza crown-6
at the nitrogen position were synthesized as the second class of cesium selective fluorescent
probes to study the effect of alkali metal ion complexation on the emission properties of
reporter fluorophore anthracene. The main difference between the newly synthesized probes
and the one mentioned above is in the composition of crown moiety that contains two
nitrogen atom in its ring bearing the fluorophore reporters. Furthermore, the mono and diaza
crown-6 probes bear only one crown ring in their core and can host only one cesium ion
compared to two crown rings that could host two cesium ions in 1,3-calix[4]bis-(9-cyano-10-
anthrylmethyl)-o-benzocrown-6. Besides good sensitivity (8.5 and 11.5 fold increase in the
emission intensity of mono and diaza crown-6 upon cesium complexation, respectively), both
probes exhibit much better tolerance for potassium ion interference without compromising
their sensitivity for cesium ion detection. These attractive features of mono and diaza crown-
6 fluorescent probes render them more effective for the detection of cesium ions in the
presence of interfering potassium ions.
PLANNED ACTIVITIES
Research will continue in an effort to find a more sensitive PET-based flourescent turn-on
indicators of alkali metal ion complexation. We will begin evaluation of the polymeric
organic matrix that will be used to attach the ionophores to the fiber optic including the
necessity of adding modifiers. The objective is to maximize both selectivity and loading as
a function of matrix variation. After metal ion binding has been characterized in solution,
studies will begin with the materials embedded in the optimized polymeric matrix. At this
stage pattern recognition analysis of the response to complex solutions will begin using an
array of selective ligands attached to an imaging fiber optic bundle. If appropriate,
different modifiers/polymers will be utilized for different selectivities/loading. If the
research proceeds as expected, the goal is to test an imaging fiber with an array of sensor
sites selective for Cs, Na, and K.
INFORMATION ACCESS
Presentations:
Hai-Feng Ji, R.Dabestani, and G.M.Brown, "Fluorescence Probes for the Detection of
Potassium Ions," presented at the American Chemical Society National Meeting, Boston,
MA, August 1998.
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Brown, Gilbert M.; Walt, David R.; Dabestani, Reza & Bonnesen, Peter V. Optically-Based Array Sensors for Selective In Situ Analysis of Tank Waste, report, June 1, 1999; Oak Ridge, Tennessee. (https://digital.library.unt.edu/ark:/67531/metadc785727/m1/3/?rotate=270: accessed May 4, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.