Investigation of Ligand Exchange on CdSe Quantum Dots via DART-MS

Abstract

Quantum dots (QDs) are an important part of many aspects of modern chemistry. Ligands play a large part in the ability to functionalize QDs. Specialized ligands, however, are ill-equipped to withstand the high temperatures of colloidal synthesis used to synthesize QDs. Ligand exchange is often used to remove the ligands used in synthesis to place ligands that are more suited to the purpose needed. One issue with ligand exchange is tracking the change of the ligands from the beginning ligand to the new ligand. NMR is sometimes used to track the exchange but it has its drawbacks. In this thesis, a method of Direct Analysis in Real-Time Mass Spectrometry (DART-MS) will be used to track the exchange for the first time. Oleate-capped CdSe QDs are made before being exchanged with dodecylamine (DDA) in increasing amounts. DART-MS is then successfully used to examine the progress of the exchange as oleate is lost from the surface and DDA is increasingly added.