A Tale of Tails: Thermodynamics of CdSe Nanocrystal Surface Ligand Exchange

Orian Elimelech, Omer Aviv, Meirav Oded, Uri Banin*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

39 Scopus citations

Abstract

The surface ligands of semiconductor nanocrystals (NCs) are central for determining their properties and for their flexible implementation in diverse applications. Thus far, the thermodynamic characteristics of ligand exchange reactions were attained by indirect methods. Isothermal titration calorimetry is utilized to directly and independently measure both the equilibrium constant and the reaction enthalpy of a model ligand exchange reaction from oleate-capped CdSe NCs to a series of alkylthiols. Increased reaction exothermicity for longer chains, accompanied by a decrease in reaction entropy with an overall enthalpy-entropy compensation behavior is observed, explained by the length-dependent interchain interactions and the organization of the bound ligands on the NCs' surface. An increase in the spontaneity of the reaction with decreasing NC size is also revealed, due to their enhanced surface reactivity. This work provides a fundamental understanding of the physicochemical properties of the NC surface with implications for NC surface ligand design.

Original languageAmerican English
Pages (from-to)6396-6403
Number of pages8
JournalNano Letters
Volume20
Issue number9
DOIs
StatePublished - 9 Sep 2020

Bibliographical note

Publisher Copyright:
Copyright © 2020 American Chemical Society.

Keywords

  • CdSe nanocrystals
  • enthalpy-entropy compensation
  • isothermal titration calorimetry
  • ligand exchange
  • nanocrystal surface analysis

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