Organic-to-Aqueous Phase Transfer of Alloyed AgInS2-ZnS Nanocrystals Using Simple Hydrophilic Ligands: Comparison of 11-Mercaptoundecanoic Acid, Dihydrolipoic Acid and Cysteine

Patrycja Kowalik; Piotr Bujak; Mateusz Penkala; Adam Pron

doi:10.3390/nano11040843

Organic-to-Aqueous Phase Transfer of Alloyed AgInS₂-ZnS Nanocrystals Using Simple Hydrophilic Ligands: Comparison of 11-Mercaptoundecanoic Acid, Dihydrolipoic Acid and Cysteine

Nanomaterials (Basel). 2021 Mar 25;11(4):843. doi: 10.3390/nano11040843.

Authors

Patrycja Kowalik^{1

2}, Piotr Bujak¹, Mateusz Penkala³, Adam Pron¹

Affiliations

¹ Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland.
² Faculty of Chemistry, University of Warsaw, Pasteura 1 Str., PL-02-093 Warsaw, Poland.
³ Institute of Chemistry, Faculty of Mathematics, Physics and Chemistry, University of Silesia, Szkolna 9, 40-007 Katowice, Poland.

Abstract

The exchange of primary hydrophobic ligands for hydrophilic ones was studied for two types of alloyed AgInS₂-ZnS nanocrystals differing in composition and by consequence exhibiting two different emission colors: red (R) and green (G). Three simple hydrophilic ligands were tested, namely, 11-mercaptoundecanoic acid, dihydrolipoic acid and cysteine. In all cases, stable aqueous colloidal dispersions were obtained. Detailed characterization of the nanocrystal surface before and after the ligand exchange by NMR spectroscopy unequivocally showed that the exchange process was the most efficient in the case of dihydrolipoic acid, leading to the complete removal of the primary ligands with a relatively small photoluminescence quantum yield drop from 68% to 40% for nanocrystals of the R type and from 48% to 28% for the G ones.

Keywords: 11-mercaptoundecanoic acid; AgInS2-ZnS alloyed nanocrystals; cysteine; dihydrolipoic acid; hydrophilic ligands; ligand exchange.