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Fluoride Ion Sensing and Caging by a Preformed Molecular D4R Zinc Phosphate Heterocubane

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Title Fluoride Ion Sensing and Caging by a Preformed Molecular D4R Zinc Phosphate Heterocubane
 
Creator KALITA, AC
MURUGAVEL, R
 
Subject TERT-BUTYL PHOSPHATE
FLUORINATED GALLIUM PHOSPHATE
RAY CRYSTAL-STRUCTURE
HIGHER YIELDING ROUTE
TURN-ON SENSOR
SOLID-STATE
FLUOROGALLOPHOSPHATE MU-2
OCTASILSESQUIOXANE CAGES
HYDROTHERMAL SYNTHESIS
SILSESQUIOXANE CAGES
 
Description Double-4-ring (D4R) zinc phosphate [Zn(dipp)(DMSO)](4) (1, dipp = 2,6-di-iso-propylphenylphosphate, DMSO = dimethyl sulfoxide), on treatment with a free fluoride ion source, exhibited ability to sense and capture fluoride ions from a variety of sources, as evidenced by extensive solution P-31 and F-19 NMR spectral titration studies. The fluoride ion-encapsulated cage [(Bu4N)-Bu-n][F@{Zn(dipp)(DMSO)}(4)] (2) was isolated in good yield from an equimolar reaction between 1 and (Bu4NF)-Bu-n in methanol and characterized by analytical and spectroscopic methods. When 1-methyl-4,4'-bipyridin-l-ium fluoride (MeQ-F) was used as the fluoride ion source a zwitterionic cage [F@{Zn-4(dipp)(4)(MeQ)(DMSO)(3)}] (3) was isolated. Crystal structure determination for 3 confirmed not only fluoride incorporation inside the D4R cage but also a weak interaction of the central fluoride ion with all four zinc centers of the cubane, resulting in a trigonal bipyramidal geometry around the zinc centers. To establish the selectivity, cubane 1 was treated with 2 equiv of MeQ-X (X = various anions) under similar conditions to isolate [F@{Zn-4(dipp)(4)(MeQ)(2)(MeOH)(2)}][X] (X = I 4; BF4 5; PF6 6) in good yields. The crystal structure determination of 4 and 5 showed that the iodide and tetrafluoroborate anions are found outside the cage while fluoride ion has entered the cavity. The final fluoride encapsulated D4R cage is anionic in 2, neutral in 3, and cationic in 4-6, showing the versatility of the cubane framework to stabilize fluoride ions in all three forms. NMR titrations showed that 1 can sense even 1 ppm level of fluoride ions and sequester them from fluoridated water and toothpaste extract.
 
Publisher AMER CHEMICAL SOC
 
Date 2014-12-28T12:25:41Z
2014-12-28T12:25:41Z
2014
 
Type Article
 
Identifier INORGANIC CHEMISTRY, 53(7)3345-3353
0020-1669
1520-510X
http://dx.doi.org/10.1021/ic500193n
http://dspace.library.iitb.ac.in/jspui/handle/100/16513
 
Language English