The interaction between some diamines and CdSe quantum dots

The interaction of some diamines (ethylenediamine (EDA), 1,6-hexanediamine (HDA), o-phenylenediamine (OPD)) with CdSe quantum dots (QDs) is reported. With increasing concentration of EDA from 0 to 2.0 × 10−6 mol l−1, slight fluorescence enhancement is observed. However, the CdSe QDs fluorescence quenching is seen at relatively higher concentration of EDA. There is a red-shift of 0–7 nm in fluorescence emission spectra of CdSe QDs when the concentration of EDA is changed from 2.0 × 10−6 to 8.0 × 10−6 mol l−1. The resonance light scattering (RLS) spectra of CdSe QDs have little change when the concentration of EDA is less than 5.0 × 10−6 mol l−1. It indicates there are little large particles formed in the solution. However, a significant increase of the RLS is observed in the 300–500 nm wavelength range after adding higher concentration than 5.0 × 10−6 mol l−1 EDA, which could be attributed to the large particles formed. The interaction between HDA and CdSe QDs is similar to that of EDA. However, with the OPD, it is found that the interaction is much different from those of EDA, HDA, and that the quenching, even at low concentration, is effective for CdSe QDs emission. The quenching phenomenon could be explained by a surface bound complexation equilibrium model.