Chiral CdTe Quantum Dots
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1241-XX02-10
Chiral CdTe quantum dots Mícheál P. Moloney, Shane A. Gallagher and Yurii K. Gun’ko* The School of Chemistry and CRANN Institute, Trinity College, University of Dublin, Dublin 2, Ireland
ABSTRACT
Quantum dots (QDs) are fluorescent semiconductor (e.g. II-VI) nanocrystals, which have a strong characteristic spectral emission. This emission is tunable to a desired energy by selecting variable particle size, size distribution and composition of the nanocrystals. QDs have recently attracted enormous interest due to their unique photophysical properties and range of potential applications in photonics and biochemistry.The main aim of our work is develop new materials based chiral quantum dots (QDs) and establish fundamental principles influencing the structure and properties of chiral QDs. Here we report the quantum efficiency control in cystein capped CdTe quantum dots (QDs) by varying ratios of enantiomeric stabilizers. We also demonstrate that the circular dichroism (CD) of CdTe QDs can be introduced by utilizing the mixture of penicillamine and cystein stabilizers of the same chirality. This approach results in QDs with the enhanced CD activity, but causes a decrease in the quantum yield and widening of the emission due to the presence of chiral defects at the nanoparticle surface.
We believe that these new QDs
could find important applications as fluorescent assays and sensors (or probes) in asymmetric synthesis, catalysis, enantioseparation, biochemical analysis and medical diagnostics.
INTRODUCTION
Symmetry and chirality are common occurrences in the natural world. Chirality is one of the most important factors of molecular recognition and therefore chiral compounds play a very significant role in chemistry, biology, and medicine. Chirality has also been envisaged to have a
great impact to nanotechnology.1-3 The understanding of the fundamental concepts relevant to chirality in nanosystems is very important for the advance of nanoscience and nanotechnology in general. Most of the research in this field was focused on chiral organic and metallorganic molecules and their supramolecular structures.4 However, the area of chiral inorganic nanoparticles is currently in the very early stage of its development. There have been a few publications on the preparation of chiral gold
5-7
and silver 8-10 nanoparticles, and recently chiral
luminescent CdS quantum dots were reported by our group.11, 12 Highly luminescent quantum confined semiconductor nanocrystals (quantum dots or QDs) are a unique class of nanomaterials which have generated a huge amount of interest in the fields of optoelectronics, photovoltalics, chemo- and biosensing.13-18 Their combination of photostability, small size and ease of surface modification19-23 makes quantum dots ideal candidates for the roles of biological probes and fluorescent sensors.19, 21, 22, 24-26 The main goal of our research is to develop new chiral QDs with unique properties by combining chiral stabilizer molecules and QDs in one species. Here we report the synt
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