Ligand-exchange of TOPO-capped CdSe quantum dots with quinuclidines

Abstract

A series of tertiary amine quinuclidine-capped cadmium selenide (Q-CdSe) quantum dots (QDs) of ~4 nm in diameter was successfully synthesized via ligand exchange process in which the original hydrophobic trioctylphosphine oxide (TOPO) ligand bound to QDs was replaced with stronger quinuclidine derivatives, quinuclidine (Q1), 3-quinuclidinone (Q2) and 3-quinuclidinol (Q3). The ligand exchange of TOPO by Q probed using the combined fluorescence and absorption spectroscopy was achieved in just only a few minutes. Moreover, disappearance of prominent C-H aliphatic stretching (~2900 cm ^-1 ) and phosphate signal (35 ppm) of TOPO-capped CdSe after replacement with Q as revealed in FT-IR and solid state ³¹ P-NMR spectra was observed indicating efficient fast ligand exchange.