Synthesis of highly luminescent POSS-coated CdTe quantum dots and their application in trace Cu2+ detection

CdTe quantum dots coated by octamercaptopropyl polyhedral oligomeric silsesquioxane (OM-POSS) were applied to detect trace Cu2+. This detection method is based on selectively quenching the fluorescence originating from the CdTe QDs in the presence of Cu2+. The research showed a low interference response of the POSS-coated CdTe QDs towards other metal ions. The POSS-coated CdTe QDs obtained a higher sensitivity than NAC-coated CdTe QDs. The quenching mechanism is discussed on the basis of the competitive binding of the thiol groups of the OM-POSS between the CdTe QDs and the metal ions. The Stern-Volmer plots at different temperatures show that the fluorescence of the POSS-coated CdTe QDs was quenched by Cu2+ through a static quenching mechanism. The response of the QDs fluorescence intensity is linearly proportional to the Cu2+ concentration ranging from 1 x 10(-8) to 1 x 10(-6) mol L-1 with a detection limit of 2.3 x 10(-9) mol L-1. Furthermore, the method has been successfully applied to the detection of Cu2+ in water samples.