Chiral Inorganic Nanostructures

Abstract

The field of chiral inorganic nanostructures is rapidly expanding. It started from the observation of strong circular dichroism during the synthesis of individual nanoparticles (NPs) and their assemblies and expanded to sophisticated synthetic protocols involving nanostructures from metals, semiconductors, ceramics, and nanocarbons. Besides the well-established chirality transfer from bioorganic molecules, other methods to impart handedness to nanoscale matter specific to inorganic materials were discovered, including three-dimentional lithography, multiphoton chirality transfer, polarization effects in nanoscale assemblies, and others. Multiple chiral geometries were observed with characteristic scales from ångströms to microns. Uniquely high values of chiral anisotropy factors that spurred the development of the field and differentiate it from chiral structures studied before, are now well understood; they originate from strong resonances of incident electromagnetic waves with plasmonic and excitonic states typical for metals and semiconductors. At the same time, distinct similarities with chiral supramolecular and biological systems also emerged. They can be seen in the synthesis and separation methods, chemical properties of individual NPs, geometries of the nanoparticle assemblies, and interactions with biological membranes. Their analysis can help us understand in greater depth the role of chiral asymmetry in nature inclusive of both earth and space. Consideration of both differences and similarities between chiral inorganic, organic, and biological nanostructures will also accelerate the development of technologies based on chiroplasmonic and chiroexcitonic effects. This review will cover both experiment and theory of chiral nanostructures starting with the origin and multiple components of mirror asymmetry of individual NPs and their assemblies. We shall consider four different types of chirality in nanostructures and related physical, chemical, and biological effects. Synthetic methods for chiral inorganic nanostructures are systematized according to chirality types, materials, and scales. We also assess technological prospects of chiral inorganic materials with current front runners being biosensing, chiral catalysis, and chiral photonics. Prospective venues for future fundamental research are discussed in the conclusion of this review.

Multiscale Nanoparticle Assembly: From Particulate Precise Manufacturing to Colloidal Processing

“…The right branch in Figure 2 displays disordered arrangements of nanoparticles, which basically exhibit the analogous behavior like the ordered ones, i.e., arrays with or without aligned atomic lattice and coalescence. [34]). On the contrary, disorder in the system might lead to additional porosity, which can be beneficial.…”

Spectroscopy for model heterogeneous asymmetric catalysis

“…Ma and coworkers summarized most of the works related to chirality transfer in 2017 where they considered four types of chirality in nanoparticles and gave examples of each . The four types are the following: (1) geometrical chirality of the inorganic core, (2) geometrical chirality of the inorganic surface (also called chiral footprint), (3) geometrical chirality of the protecting shell, and (4) chiral field effect.…”

Chiral Perovskites: Promising Materials toward Next‐Generation Optoelectronics

“…The unique attribute of chiral photonics lies on the ability of differently rotating and controlling the plane of polarization of linear and nonlinear optical functions. Chiral systems are thus of great importance in various aspects, from biological science to the optical and electronic device applications . It is well known that the addition of chiral ligands can break the symmetric alignment of centric perovskites .…”