Post-synthetic phase transfer ligand exchange has been established as a simple, reliable, and versatile method for the synthesis of chiral, optically active colloidal nanocrystals displaying circular dichroism (CD) and circularly polarized luminescence (CPL). Herein we present a water-free and purification-free cyclohexane → methanol ligand exchange system that led to the synthesis of stable, non-aggregating chiral and fluorescent cadmium sulfide quantum dots (CdS QDs). Absorption and emission studies revealed that the carboxylate capping ligands can tune the band gap by up to 65 meV as well as control the band gap and deep trap emission pathways. The CD data revealed that the addition of a 2nd stereogenic center did not automatically lead to an increase of the CD anisotropy of QDs, but rather match/mismatch cooperativity effects must be considered in the transfer of the chirality from the capping ligands to the achiral nanocrystals. Variation in position of the functional groups as well as the chemical identity of the functional groups impacted both the shape and anisotropy of the induced CD spectra and revealed the importance of the functional groups’ coordination and polarity on the binding geometry and induced chiroptical properties. Finally, we describe the first example where CD spectra of QDs capped with the same ligand and dissolved in the same solvent displayed very different spectral profiles. This work provides deeper insight into induced CD of QDs and paves the path to rational design of chiral nanomaterials.
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This content will become publicly available on February 2, 2024
Anionic ligand-induced chirality in perovskite nanoplatelets
Perovskite materials passivated by chiral ligands have recently shown unique chiroptical activity with promising optoelectronic applications. However, the ligands have been limited to chiral amines. Here, chiral phosphate molecules have been exploited to synthesize CsPbBr 3 nanoplatelets. The nanoplatelets showed a distinct circular dichroism signal and maintained their chiroptical properties after purification with anti-solvent.
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- NSF-PAR ID:
- 10419956
- Date Published:
- Journal Name:
- Chemical Communications
- Volume:
- 59
- Issue:
- 11
- ISSN:
- 1359-7345
- Page Range / eLocation ID:
- 1485 to 1488
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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