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Circular dichroism of surface complexes based on quantum dots and azo dye
Evgeny V Kundelev1, Anna O Orlova1, Vladimir G Maslov1
1Department of Optical Physics and Modern Natural Science, ITMO University, Saint Petersburg, Russia.
Chirality
|November 28, 2017
Summary
Chiral surface complexes were created using cadmium selenide/zinc sulfide quantum dots (QDs) and a dye. These complexes exhibit strong circular dichroism, useful for sensing applications.
Area of Science:
- Materials Science
- Spectroscopy
- Quantum Chemistry
Background:
- Quantum dots (QDs) are semiconductor nanocrystals with tunable optical and electronic properties.
- Chirality is a crucial property in various scientific fields, including chemistry and biology.
- Surface functionalization of QDs allows for the creation of novel hybrid materials with tailored characteristics.
Purpose of the Study:
- To investigate the chiral properties of surface complexes formed by CdSe/ZnS quantum dots (QDs) and 1-(2-pyridylazo)-2-naphthol (PAN) azo dye.
- To synthesize water-soluble chiral QD-PAN complexes using L-cysteine (Lcys) and D-cysteine (Dcys) capping ligands.
- To understand the origin of chirality in these complexes through spectroscopic and computational methods.
Main Methods:
- Circular dichroism (CD) spectroscopy was employed to study the chiral properties.
- UV-vis, Fourier-transform infrared (FTIR), and CD spectroscopy were used for complex characterization.
- Time-dependent density-functional theory (TDDFT) calculations were performed to simulate CD spectra.
Main Results:
- Water-soluble chiral QD-PAN complexes were successfully synthesized using Lcys and Dcys ligands.
- Experimental and TDDFT-calculated CD spectra showed consistent sign patterns, confirming the induced chirality.
- The binding of Lcys/Dcys and PAN to the same Zn atom on the QD surface was identified as the source of chirality.
- The QD-PAN complexes exhibited significantly larger circular dichroism compared to QDs functionalized solely with cysteine.
Conclusions:
- The study successfully demonstrates the creation of chiral surface complexes with enhanced circular dichroism using CdSe/ZnS QDs and PAN.
- The binding configuration of ligands and dye on the QD surface dictates the observed chirality.
- These chiral QD-PAN complexes hold potential for applications in chiral sensing and optical devices.
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