Chiroptical Properties of Semiconductor QDs

Chiral quantum dots (QDs) are expected to have a range of potential applications in biosensing, labeling, environmental nanoassays, chiral memory, building blocks for the bottomup nanofabrication of chiroptical devices and nanoassemblies, and fluorescent chiral nanoprobes in biomedical and analytical technologies[1,2]. We studied the chiroptical properties of colloidal solution of quantum dots (QDs) which were initially prepared with use of chiral ligands (diaminocyclohexane molecules). We demonstrate completely different circular dichroism (CD) activities of QDs capped with different amount of ligands. We consider that the chiroptical activity is caused by coupling between electric field of the chiral molecules and QDs in case of small amount of ligands. On the contrary, in case of excess amount of ligands, the chiral aggregate of diaminocyclohexane molecules is a significant contributor to the CD activities. Moreover, circularly polarized luminescence (CPL) of chiral QDs is discussed in details. Such optimized design and modulation of chiroptical properties will likely lead to novel applications in chiral biosensing and chiroptical nanomaterials.

References:
1.Mícheál P Moloney, Joseph Govan, Alexander Loudon, Maria Mukhina & Yurii K Gun'ko, Preparation of chiral quantum dots, Nature Protocols 10, 558-573 (2015).
2.U. Tohgha, K. K. Deol, A. G. Porter, S. G. Bartko, J. Kyu Choi, B. M. Leonard, K. Varga, J. Kubelka, G. Muller, M. Balaz, Ligand Induced Circular Dichroism and Circularly Polarized Luminescence in CdSe Quantum Dots, ACS Nano 7 (12), 11094–11102 (2013).