Chiral Surface and Geometry of Metal Nanocrystals

Abstract

and their microscopic assembling and folding gradually give rise to chirality and left-right asymmetry from supramolecules to organelles, cells, and macroscopic organisms. Although the origin of homochirality is still unexplained and opens to arguments, investigating the chirality of matter and its origination is a central part of understanding asymmetric physical and chemical phenomena. The importance of chirality in chemistry lies in the asymmetric biochemical reactions with different physiological effect, which has paramount importance in biochemistry and pharmaceutical industry. [3,14,15] A mirror image of chiral objects can be determined into one of the left-handed or right-handed forms of geometry, called enantiomer or enantiomorph. Both enantiomers of a chiral object consist of identical chemical compositions but indeed are significantly different in their light-matter interaction, catalysis, and biological functions. The enantioselective signaling and enzymatic reaction are attributed to the homochirality of the living organism and its biological receptors, which are only composed of l-form amino acids and d-form sugars in nature. [7,14,15] Thalidomide is often referred to as a representative but also the most tragic example. The R-form of this drug is harmless to the body and was released as a painkiller for pregnant women, but its enantiomer causes severe malformation in the limbs of infants. [15,16] Since then, it has been a requirement for drugs to be characterized as a single enantiomer to be approved. 3D chirality is a unique characteristic of life, and the stereochemical aspect of molecular materials has come to fore of modern chemistry and biology. The optical property of chiral compounds, the so-called chiroptical effect, is highly effective for observing chirality in a nondestructive manner. [17] Chiroptical effects can be used for determination of the absolute configuration and enantiomeric excess of chiral molecules and as an optical probe for estimating the 3D structure of biomacromolecules such as proteins and DNA. [18] However, in most chiral organic molecules and biomolecules, chiroptical effects are typically very weak due to the much smaller size of molecules than the wavelength of exciting light. Integration of inorganic nanomaterials is one promising method for increasing the chiroptical signal of molecules; it focuses the light into nanoscale area to maximize the lightmatter interaction. [19-22] For example, a complex spatial profile Chirality is a basic property of nature and has great importance in photonics, biochemistry, medicine, and catalysis. This importance has led to the emergence of the chiral inorganic nanostructure field in the last two decades, providing opportunities to control the chirality of light and biochemical reactions. While the facile production of 3D nanostructures has remained a major challenge, recent advances in nanocrystal synthesis have provided a new pathway for efficient control of chirality at the nanoscale by transferring molecular chirality to the geo...

Electromagnetic chirality: from fundamentals to nontraditional chiroptical phenomena

“…Furthermore, we anticipate that the concept of machine learning will be utilized for the automatic design and optimization of chiral structures with desired optical properties 172 – 175 . This will provide a new perspective to understand and facilitate chiroptical phenomena and devices, and further promote the applications of chiroptical platforms, especially in the fields of, but not limited to, metamaterials 176 , 177 , sensing 178 , spintronics 179 , and stereochemistry 180 .…”

Chirality communications between inorganic and organic compounds

“…The D-cysteine would bind~0.3 kcal/mol stronger than L-cysteine on an S-type Au (17,11,9) surface ( Figure 6B), 100 and such asymmetric adsorption has been confirmed by X-ray photoelectron spectroscopy. 96 Gellman et al 101 used temperature-programmed desorption (TPD) to measure the R-3-methylcyclohexanone desorption on different chiral Cu surfaces, such as (643), (653), (651), (13,9,1), (17,5,1), (821), and (531). The |ΔΔE des | was found to range from~0.63 to 1.08 kcal/mol.…”

“…(C1) asymmetric shapes; (C2) crystals of chiral lattice, the lattices here show enantiomorphic α‐quartz crystal and corresponding crystal structure. Adapted with permission 5 . Copyright 2019, Wiley‐VCH.…”

“…Chiral molecules are found important in life science, agrochemicals, pharmaceutical industries, biosensing, display materials, and so forth. [1][2][3][4][5] Chirality stems from a structure lacking symmetry elements of inversion symmetry and mirror-plane, which makes the structure not superimposable with its mirror image. Without these two kinds of symmetries, any structure is chiral, besides conventional chiral organics or spiral inorganic structures.…”

Single Nanoparticle Chiroptics in a Liquid: Optical Activity in Hyper-Rayleigh Scattering from Au Helicoids

“…Within this context, a new type of 3D chiral nanomaterials has emerged, namely, chiral metal nanocrystals (also known as helicoids), 17 − 19 where the chirality of the nanoparticles has purely crystallographic (high Miller index) origin and is obtained by chirality transfer from molecules. 19 Although high Miller index surfaces are well-known for exhibiting chirality, the uniqueness of the helicoids is that this “surface chirality” develops into a morphological/crystallographic chirality in the full three-dimensional (3D) nanoparticle. The solution-based, bottom-up fabrication process is inherently scalable and compatible with liquid phase applications in chemical and biological processes.…”