Making a Right or Left Choice: Chiral Self-Sorting as a Tool for the Formation of Discrete Complex Structures

Abstract

This review discusses chiral self-sorting-the process of choosing an interaction partner with a given chirality from a complex mixture of many possible racemic partners. Chiral self-sorting (also known as chiral self-recognition or chiral self-discrimination) is fundamental for creating functional structures in nature and in the world of chemistry because interactions between molecules of the same or the opposite chirality are characterized by different interaction energies and intrinsically different resulting structures. However, due to the similarity between recognition sites of enantiomers and common conformational lability, high fidelity homochiral or heterochiral self-sorting poses a substantial challenge. Chiral self-sorting occurs among natural and synthetic molecules that leads to the amplification of discrete species. The review covers a variety of complex self-assembled structures ranging from aggregates made of natural and racemic peptides and DNA, through artificial functional receptors, macrocyles, and cages to catalytically active metal complexes and helix mimics. The examples involve a plethora of reversible interactions: electrostatic interactions, π-π stacking, hydrogen bonds, coordination bonds, and dynamic covalent bonds. A generalized view of the examples collected from different fields allows us to suggest suitable geometric models that enable a rationalization of the observed experimental preferences and establishment of the rules that can facilitate further design.

Chiral Self‐Discrimination and Guest Recognition in Helicene‐Based Coordination Cages

“…[5] More recently, chiral metallo-supramolecular self-assembled rings and cages have been introduced as selective receptors and enzyme-like nanoreactors based on chiral backbones, auxiliaries, the inherent chirality of stereogenic metal centers, or the overall architecture. [6] Upon metal coordination, racemic mixtures of ligands may undergo chiral self-sorting, [7] leading to homochiral [8][9][10] or heterochiral [10,11] assemblies. Beyond their use in enantioselective recognition, chiral cages based on luminescent metal centers have been shown to exhibit unique chiroptical properties.…”

Self‐Sorting Double‐Network Hydrogels with Tunable Supramolecular Handedness and Mechanical Properties

“…Most of the constructed self‐sorting systems are manipulated by noncovalent interactions, such as hydrogen‐bonding interactions, solvophobic effects, host–guest interactions, and metal–ligand interactions . However, self‐sorting in biological systems and bioinspired self‐assembly processes often rely on chiral molecules . By mimicking self‐sorting with hierarchical chirality and programmable functions in nature, molecular self‐assembly serves as a universal and efficient strategy for bottom‐up fabrication of nanostructures, because small synthetic molecules could be readily designed and endowed with functionality, and their self‐assembly could also be readily controlled by intermolecular noncovalent forces .…”

One‐step Access to Resorcinsalens—Solvent‐Dependent Synthesis, Tautomerism, Self‐sorting and Supramolecular Architectures of Chiral Polyimine Analogues of Resorcinarene

“…The use of racemic substrates in cycloimination reactions often provides complex mixtures of diastereoisomers. Chiral self‐sorting is achieved in those DCC‐based reactions for which the products significantly differ in symmetry and hence in rotational entropy …”

“…Chiral self-sorting is achieved in those DCC-based reactions for which the products significantly differ in symmetry and hence in rotationale ntropy. [6,7] Due to the diequatorial position of amino groups and skeleton rigidity, trans-1,2-diaminocyclohexane (DACH, 1)i st he amine of choice for cycloimination. Although the quantitative [3+ +3] cyclocondensationr eactions between 1 and variousa romatic 1,4-dialdehydes provide triangularm acrocycles( trianglimines) of symmetry and shape depending on the aldehyde structure, [8,9] the reactions utilizing 1,3-dialdehydes are less selective.…”