Colloidally Prepared 3‑Mercaptopropionic Acid Capped Lead Sulfide Quantum Dots

Colloidally suspended PbS quantum dots stabilized with 3-mercaptopropionic acid (3-MPA) were prepared via solution ligand exchange. The optical properties of the as-prepared colloidal QDs were investigated by absorption and emission spectroscopy. The 3-MPA exchanged QDs luminesced with intensities comparable to oleate capped PbS QDs. The nanocrystal ligand chemistry was investigated by solution ¹H Nuclear Magnetic Resonance (NMR) spectroscopy, which indicated a dynamic ligand shell undergoing rapid exchange. Optical properties of the QD colloid evolved over time and were correlated to the oxidative conversion of 3-MPA into dithiodipropionic acid (DTDPA) in the presence of dimethyl sulfoxide (DMSO) observed by NMR