Metal ion complexation in acetonitrile by upper-rim allyl-substituted, di-ionized calix[4]arenes bearing two dansyl fluorophores |
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Authors: | Ümmühan Ocak Miraç Ocak Xiaodong Liu |
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Institution: | a Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409-1061, USA b Department of Chemistry, Faculty of Arts and Sciences, Karadeniz Technical University, 61080 Trabzon, Turkey |
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Abstract: | The influence of Li+, Na+, K+, Rb+, Cs+, Mg2+, Ca2+, Sr2+, Ba2+, Ag+, Cd2+, Co2+, Fe2+, Hg2+, Mn2+, Pb2+, Zn2+ and Fe3+ on the spectroscopic properties of two dansyl (1-dimethylaminonaphthalene-5-sulfonyl) groups linked to the lower rims of a series of three, structurally related, di-ionized calix4]arenes is investigated by means of absorption and emission spectrophotometry. Di(tetramethylammonium) salts of the di-ionized ligands, L, L1, and L2, which differ in having no, two and four allyl groups, respectively, on the upper rim of the calix4]arene scaffold, are utilized for the spectrofluorimetric titration experiments in MeCN. On complexation by alkaline earth metal cations, the emission spectra undergo marked red shifts and quenching of the dansyl fluorescence. These effects are weaker with alkali metal cations. Transition metal cations and Pb2+ interact strongly with the ligands. In particular, Fe3+, Hg2+ and Pb2+ cause greater than 99% quenching of the dansyl fluorescence. |
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Keywords: | Calixarene ligand Fluorescence spectroscopy Stability constant Metal ion complexation |
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