Synthesis Of Cdte Nanocrystals Assisted By Ionic Liquids And Responsive Selectivity Toward Ions / Molecules

Cd Te nanocrystals(NCs) have been widely applied in many fields including solar cell, analysis and detection, fluorescence imaging and so on. They are usually synthesized in aqueous solutions using mercapto-carboxylic acid as surface stabilizer such as mercapto-propionic acid(MPA) and thioglycolic acid. In this paper, the thio-functionalized ionic liquids were employed as surface stabilizer,and the ligand functionalized Cd Te NCs were synthesized by hydrothermal routes. The as-synthesized Cd Te NCs exhibit excellent selectivity and sensitivity toward the specified ions and molecules. The main contents are as follows:1. Cd Te NCs were synthesized in the water-ethylenediamine-ionic liquid systems by optimizing systematically the reaction conditions. Four kinds of thio-functionalized ionic liquid with different alkyl chain length in imidazolium were used as surface stabilizer to prepare Cd Te NCs(Cd Te@[EMIm]MPA, Cd Te@[BMIm]MPA and Cd Te@[OMIm]MPA) by the hydrothermal routes. The optimal reaction conditions to prepare the Cd Te NCs were determined including reaction temperature, reaction time, the concentration of ethylenediamine, the concentration of ionic liquid and the ratio of HTe-/Cd2+.2. The influence of p H on the fluorescence intensity was shown for the aqueous solutions of Cd Te NCs. The fluorescence intensity of Cd Te@[EMIm]MPA、Cd Te@[BMIm]MPA and Cd Te@[OMIm]MPA NCs present a trend that first increases and then decreases with increasing p H, and respectively the strongest fluorescence intensity at p H values of 9.7, 10.2 and 10.5.3. Compared with the results of literature reported, the thio-functionalized ionic liquid capped Cd Te NCs exhibit the outstanding selectivity and sensitivity in detecting Co2+ and Mn2+ in aqueous solutions. It is shown that the detecting limits of Cd Te@[EMIm]MPA NCs toward Co2+ and Mn2+ respectively are 2.5×10-10-2.5×10-5 M and 2.5×10-8-5×10-4 M; Cd Te@[BMIm]MPA NCs respectively are 2.5×10-7-2.5×10-5 M and 2.5×10-6-2.5×10-4 M; Cd Te@[OMIm]MPA NCs respectively are 2.5×10-9-2.5×10-5 M and 2.5×10-9-2.5×10-5 M.4. The studied results show that the concentration ranges of organic molecules, which are detected by the thio-functionalized ionic liquid capped Cd Te NCs, have nothing to do with the alkyl chain length in imidazolium ring. For p-nitropheno and VB12, the detecting ranges of the molecules by the Cd Te NCs are 2.5×10-5-5×10-3 M and 2.5×10-6-1.8×10-5 M, respectively.