CdSe Quantum Dots Functionalized with Chiral, Thiol-Free Carboxylic Acids

Unraveling Structural Requirements for Ligand-Induced Chirality

Krisztina Varga, Shambhavi Tannir, Benjamin E. Haynie, Brian M. Leonard, Sergei V. Dzyuba, Jan Kubelka, Milan Balaz

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Functionalization of colloidal quantum dots (QDs) with chiral cysteine derivatives by phase-transfer ligand exchange proved to be a simple yet powerful method for the synthesis of chiral, optically active QDs regardless of their size and chemical composition. Here, we present induction of chirality in CdSe by thiol-free chiral carboxylic acid capping ligands (l- and d-malic and tartaric acids). Our circular dichroism (CD) and infrared experimental data showed how the presence of a chiral carboxylic acid capping ligand on the surface of CdSe QDs was necessary but not sufficient for the induction of optical activity in QDs. A chiral bis-carboxylic acid capping ligand needed to have three oxygen-donor groups during the phase-transfer ligand exchange to successfully induce chirality in CdSe. Intrinsic chirality of CdSe nanocrystals was not observed as evidenced by transmission electron microscopy and reverse phase-transfer ligand exchange with achiral 1-dodecanethiol. Density functional theory geometry optimizations and CD spectra simulations suggest an explanation for these observations. The tridentate binding via three oxygen-donor groups had an energetic preference for one of the two possible binding orientations on the QD (111) surface, leading to the CD signal. By contrast, bidentate binding was nearly equienergetic, leading to cancellation of approximately oppositely signed corresponding CD signals. The resulting induced CD of CdSe functionalized with chiral carboxylic acid capping ligands was the result of hybridization of the (achiral) QD and (chiral) ligand electronic states controlled by the ligand's absolute configuration and the ligand's geometrical arrangement on the QD surface.

Original languageEnglish
Pages (from-to)9846-9853
Number of pages8
JournalACS Nano
Volume11
Issue number10
DOIs
Publication statusPublished - 2017 Oct 24

Fingerprint

Chirality
Carboxylic Acids
Carboxylic acids
chirality
Sulfhydryl Compounds
thiols
carboxylic acids
Semiconductor quantum dots
Ligands
quantum dots
requirements
ligands
Dichroism
dichroism
induction
Oxygen
optical activity
cysteine
Electronic states
oxygen

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

Cite this

Varga, Krisztina ; Tannir, Shambhavi ; Haynie, Benjamin E. ; Leonard, Brian M. ; Dzyuba, Sergei V. ; Kubelka, Jan ; Balaz, Milan. / CdSe Quantum Dots Functionalized with Chiral, Thiol-Free Carboxylic Acids : Unraveling Structural Requirements for Ligand-Induced Chirality. In: ACS Nano. 2017 ; Vol. 11, No. 10. pp. 9846-9853.
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CdSe Quantum Dots Functionalized with Chiral, Thiol-Free Carboxylic Acids : Unraveling Structural Requirements for Ligand-Induced Chirality. / Varga, Krisztina; Tannir, Shambhavi; Haynie, Benjamin E.; Leonard, Brian M.; Dzyuba, Sergei V.; Kubelka, Jan; Balaz, Milan.

In: ACS Nano, Vol. 11, No. 10, 24.10.2017, p. 9846-9853.

Research output: Contribution to journalArticle

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AU - Tannir, Shambhavi

AU - Haynie, Benjamin E.

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