Interaction of β-cyclodextrin-capped CdSe quantum dots with inorganic anions and cations.
A facile method was developed for the preparation of water soluble β-Cyclodextrin (β-CD)-modified CdSe quantum dots (QDs) (β-CD-QDs) by directly replacing the oleic acid ligands on the QDs surface with β-CD in an alkaline aqueous solution. The as-prepared QDs show good stability in aqueous solution for several months. Oxoanions, including phosphoric acid ion, sulphite acid ion and carbonic acid ion, affect the fluorescence of β-CD-QDs. Among them, H(2)PO(4)(-) exhibited the largest quenching effect. For the polyprotic acids (HO)(3)AO, the effect of acidic anions on the fluorescence of β-CD-QDs was in the order: monoanion (HO)(2)AO(2)(-) > dianion (HO)AO(3)(2-) >> trianion AO(4)(3-). After photoactivation for several days in the presence of anions at alkaline pH, the β-CD-QDs exhibited strong fluorescence emission. The effect of various heavy and transition metal ions on the fluorescence properties of the β-CD-QDs was investigated further. It was found that Ag(+), Hg(2+) and Co(2+) have significant quenching effect on the fluorescence of the β-CD-QDs. The Stern-Volmer quenching constants increased in the order: Hg(2+) < Co(2+) <Ag(+). The adsorption model of metal ions on β-CD-QDs was explored.
School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, People's Republic of China.
Zhuo Bin
ZB
Shang
Shuang
S
Hu
Yu
Y
Wang
Wei Jun
WJ
Jin
D000838:Anions; D019187:Cadmium Compounds / Q000737:chemistry*; D002412:Cations; D046529:Microscopy, Electron, Transmission; D045663:Quantum Dots; D018036:Selenium Compounds / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D047392:beta-Cyclodextrins / Q000737:chemistry*
D000838:Anions; D019187:Cadmium Compounds; D002412:Cations; D018036:Selenium Compounds; D047392:beta-Cyclodextrins; C058667:cadmium selenide; C031215:betadex