Lewis acidic stiborafluorenes for the fluorescence turn-on sensing of fluoride in drinking water at ppm concentrations

摘要: Prompted by the importance of fluoride in fields such as drinking water analysis and 18F-positron emission tomography, we have synthesized investigated three Lewis acidic organostiboranes containing (2,2′-biphenylene)phenylantimony(V) moiety a common subunit catecholate (1), tetrachlorocatecholate (2) or an alizarin (alizarin = 1,2-dihydroxyanthraquinone) ligand (3). DFT calculations show that acidity these stiboranes arises from presence low lying antimony-centered orbital. While 1 shows no measurable anion affinity 7/3 vol. THF–water mixtures, spectrophotometric titrations more electron deficient 2 3 bind anions same medium with binding constants (K) 13 500 (±1400 M−1) for 16 100 (±1100) M−1 3. Formation complexes has been confirmed isolation TAS[2–F] TAS[3–F] (TAS tris(dimethylamino)sulfonium), structures which also determined. formation [2–F]− does not trigger marked photophysical response, color change yellow to dark red is observed upon conversion into [3–F]− CH2Cl2. This change, using TD-DFT calculations, accompanied increase fluorescence chromophore at 616 nm. Owing its high turn-on properties, can be used biphasic water–CH2Cl2 mixtures assay sub-ppm fluoridation levels tap bottled infant waters.