IntroductionQuantum dots (QDs), due to their variety of size-and shape-dependent optical and electrical properties [1,2], have been attracting extensive attention for numerous applications such as in biological labels, photovoltaic devices, and optoelectronic devices [3 5]. In particular, they are very attractive as QD-based optical sensors for detecting biomolecules, small molecules, and cations or anions due to their high fluorescence quantum yields, good photostability, and negligible photobleaching in comparison with dyes [6 10]. CdTe is an important semiconductor material and CdTe QDs show increasing promise due to their large exciton Bohr radius (7.3 nm) and narrow ABSTRACTA facile one-pot microwave irradiation reduction route has been developed for the synthesis of highly luminescent CdTe quantum dots using Na 2 TeO 3 as the Te source in an aqueous environment. The synthesis parameters of this simple and rapid approach, including the reaction temperature and time, the pH of the reaction solution and the molar ratio of the 3-mercaptopropionic acid (MPA) stabilizer to Cd 2+ , have considerable infl uence on the particle size and photoluminescence quantum yield of the CdTe quantum dots. The photoluminescence quantum yield of CdTe quantum dots prepared using relatively short reaction times (10 40 min) reached 40% 60% (emission peaks at 550 640 nm). Furthermore, the resulting products could be used as fl uorescent probes to detect Hg 2+ ions in aqueous media. The response was linearly proportional to the concentration of Hg 2+ ion in the range 8.0×10 9 mol/L to 2.0×10 6 mol/L with a detection limit of 2.7×10 9 mol/L.

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Highly defect-related luminescent aqueous CdSe quantum dots (QDs) were successfully synthesized by using sulfanylsuccinic acid (SSA) as capping ligands at low temperature by water bath. The photoluminescence quantum yields (PL QYs) of as-prepared CdSe QDs could reach up to 30%. XRD and HRTEM characterization suggest an amorphous state.

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The molecular structures and vibrational frequencies of [C 6 H 5 SH-(H 2 O) n ]•ϩ (n ϭ 1-4) clusters are studied employing B3LYP density functional theory (DFT) with a 6-311ϩϩG** basis set. The features related to structures of the SH stretching vibrational spectrum of the thiophenol and of the intermolecular stretching vibration of S . . . HOO are also obtained and discussed in detail. The stable structures show that the hydrogen bonds between the thiophenol cation radical and water molecules are stronger than that between neutral thiophenol and water molecules and become stronger along with the increased water number n. Thus, the possibility of proton transfer depends on the water number; that is, the position of the proton of the thiophenol cation radical lies on the water number n. The theoretically obtained charge distribution and energy indicate simultaneously that (i) the cluster ions with n ϭ 1-2 have the proton-nontransferred form; (ii) the cluster ion with n ϭ 3 settles mainly on the proton-transferred branched form; and (iii) in the case of n ϭ 4 cluster ions, can be a mixture of proton-transferred ringed and branched forms.