Plasmon-Assisted Chemistry Using Chiral Gold Helicoids: Toward Asymmetric Organic Catalysis

Abstract

High Resolution Image Download MS PowerPoint Slide Gold nanoparticles with shape-determined chirality enable the attainment of plasmon-associated optical activities exceeding those exhibited by all previously known natural objects. These nanoparticles, together with their subdiffraction light focusing and excitation of chiral, plasmon-related near-fields, offer a range of very interesting applications. Herein, we propose the use of these chiral plasmon nanoparticles for asymmetric organic catalysis with the implementation of optically active organic probes (alkoxyamines). Plasmon triggering causes the homolysis of the C–ON bond in the structure of the employed organic molecules, forming stable radicals, which can be easily detected using electron paramagnetic resonance spectroscopy. Our investigation delves into the influence of various parameters on the catalytic process, such as the chirality of the nanoparticles, the not-required circular polarization of the incident light, and the optical activity of the probes used. The results clearly show that the efficiency of a chemical reaction depends on all of these factors but to different extents. The “correct” combination of these parameters facilitates the attainment of the highest chemical reaction rate. To the best of our knowledge, this study pioneers the use of inherently chiral plasmon-based nanoparticles for asymmetric organic transformations. The proposed route of chiral plasmon catalysis can be used in various fields, including polarization-controlled chemistry, asymmetric catalysis, and the enantioselective separation of organic compounds (through the preferential elimination of one enantiomer).