Supramolecular chirality of multicomponent self-assembled systems and their applications

Abstract

<p indent=0mm>Chirality is closely associated with life, such as amino acids at the molecular level, secondary structures of proteins (DNA, RNA), nanoscale helices and macroscopic conches. Due to the dynamic property of non-covalent bond, self-assembly of molecule shows environmental adaptability. The stacking form of molecule can be regulated via tunning non-covalent interaction. The asymmetric aggregation of molecular building blocks is called supramolecular chirality which is not only related to the structure of molecule and molecular chirality, but also influenced by non-covalent interaction. Regulation of the emergence, amplification, transfer and inversion of supramolecular chirality is an important field. The assemblies with supramolecular chirality are usually driven by various non-covalent interactions with unique chiral micro-environment. Design and fabrication of supramolecular assemblies with two or more kinds of components are much more complex than the single component systems due to the complexity of possible pathways. Compared with single-component systems which have already matured, both basic and application research of multi-component supramolecular chiral assemblies are still limited. However, the study of supramolecular chirality of multicomponent self-assembled systems not only benefit to simulate complex biological systems, but also contribute to the deep understanding of the origin of homochirality in nature to further apply in bionics, which is of great significance. Therefore, in this review article, we mainly discuss the construction of multicomponent self-assembled systems including solvent effect, hydrogen bond, structural analogues, organic/inorganic co-assembly. Solvent polarity has a great influence on self-assembled process of molecules especially for amphiphiles whose molecular stacking layer that exposes to solvents should be solvophilic. Besides the effect of polarity, solvent molecules also could act as an active component to participate self-assembled process generating significant influence on self-assembly behavior and even supramolecular chirality. Due to the directionality and relatively strong intensity compared with other non-covalent interactions, hydrogen bonding has been considered as the important interaction to construct supramolecular assemblies. Hydrogen bonding could be widely observed among amide/imide, ureido and carboxylic acid groups which has been introduced in this review in detail. And the influence of hydrogen bond to supramolecular chirality also has been fully discussed. Introducing structural analogues into building block with chiral center is another effective method to construct multicomponent supramolecular assemblies. Two different paths upon the aggregation of structural analogues including self-sorting and coassembly might occur which are controlled via equilibrium of kinetically or thermodynamically. The realization of coassembly between structural analogues requires strong interactions between components or similarly staking mode. Because of the excellent properties of inorganic material especially in luminescence, inorganic/organic coassembled materials which could be applied in chiroptical with tunable chiral and optical properties have emerged. Moreover, a serial of three component supramolecular assemblies with tunable chiral and optical properties based on the research of double components have been developed. Strong non-covalent interactions including hydrogen bond and π-π stacking interaction are benefit for forming multicomponent supramolecular chiral assemblies. Besides design and fabrication multicomponent supramolecular chiral assemblies, we also introduced their applications in chiral recognition, circularly polarized luminescence (CPL), chiral catalysis and chiral template. Chiral recognition not only displays the interaction between achiral molecules with various chiral molecules, but also between supramolecular assemblies with chiral molecules. We mainly discussed the recognition of supramolecular assemblies to enantiomers. CPL is a nonnegligible application field of multicomponent supramolecular chiral assemblies which has attracted increasing attention due to its wide potential applications in optical displays, encryption and storage of information, photoelectric devices, chiroptical materials, and so on. Catalysts for asymmetric reactions under mild conditions have been widely studied based on different supramolecular assemblies including helical nanorods, nanotubes and vesicles. We expect this review will serve as an introduction and reference for researchers who are interested in exploring this field.