In situ spectroscopic characterization of a solution-phase X-type ligand exchange at colloidal lead sulphide quantum dot surfaces

Abstract

We employed quantitative NMR spectroscopy and spectrophotometric absorbance titration to study a quantum dot X-type ligand exchange reaction. We find that the exchange is highly cooperative, where at low extents of exchange the change in free energy of the reaction, ΔG_XC, is ∼11 kJ mol⁻¹ while at higher extents of exchange ΔG_XC saturates to ∼−4 kJ mol⁻¹. A modified Fowler binding isotherm is developed to describe the reaction.