Inorganic Chiral Nanoparticles—A Promising Chiral Trigger to Induce Homochirality

Origin of homochirality is a fundamentally important but yet unanswered question. One of the keys to answer this question is to understand external chiral forces to trigger symmetry breaking, which has been believed to induce the homochirality. Diverse chiral forces have been proposed, but one is missing: inorganic chiral surfaces have an enantiospecific interaction with prochiral molecules, considering the fact when the Earth formed about 4.5 billion years ago, it was prebiotically composed of inorganic minerals, mostly crystalline in nature and some are chiral, followed by the existence of organic life. We are studying chiral forces contributed from inorganic atomically chiral surfaces.<br/><br/>We use glancing angle physical vapour deposition to fabricate inorganic chiral nanoparticles (or CNPs), which have adjustable optical activities in the UV-visible-near infrared region. Inorganic CNPs are made of diverse metals, alloys and oxides, and composed of chiral structures at the atomic scale, including chiral twisting of multi-layers of achiral facets, high-index chiral facets, and chiral defects. Inorganic CNPs enantiospecifically interact with prochiral molecules, leading to an enantiospecific amplification of molecular optical activity, an enantioselective photoinduced cyclodimerization of a prochiral anthracene derivative, and reliable manipulation of symmetry breaking of prochiral helicenes. Our works shed light on the origin of homochirality (or life) stemming from the atomically chiral surfaces of minerals through the enantiospecific interactions with prochiral molecules.