Nisha Shukla, Institute for Complex Engineered Systems, Carnegie Mellon Univeristy, 5000 Forbes Ave., Pittsburgh, PA 15213, Andrew J. Gellman, Chemical Engineering, Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh, PA 15213, and Melissa Bartel, Chemical Engineering, Carnegie Mellon Univeristy, 5000 Forbes Ave., Pittsburgh, PA 15213.
Layers of organic ligands on the surfaces of nanoparticles dictate many of their properties. Chiral Au nanoparticles have been synthesized by coating with chiral ligands. These ligands render the surface of the particles chiral and active for enantioselective adsorption and other enantioselective processes.
The chirality of the Au nanoparticles has been probed by exposing them to racemic mixtures of propylene oxide. Optical polarization has been used to detect enantiospecific interactions between the propylene oxide and the chiral Au nanoparticles. These measurements show that the chiral Au nanoparticles do selectively adsorb one of the two enantiomers form the racemic mixture, resulting in a net polarization of light passing through the solution of chiral Au nanoparticles and racemic propylene oxide. The polarization depends on the concentration of racemic propylene oxide in solution.