Synthesis of a large-cavity carbazole macrocycle for size-dependent recognition

Efficient macrocyclization facilitated by skeleton preorganization

Reported here is the efficient macrocyclization facilitated by skeleton preorganization. A pyridylcarbazole macrocycle and a phenylpyridylcarbazole macrocycle was synthesized in yield up to 75%. Single-crystal structures and theoretic computation uncovered that the skeleton preorganization promoted the formation of cyclization-favorable conformation of noncyclic precursors via π⋯π interactions. This result provided a new approach for the efficient syntheses of macrocycles.

Giant Cavity Macrocycle: Synthesis, Structure, and Its Complexation with Pagoda[5]arene

A novel stretched hexagon structure naphthalene diimides-extended-pillar[6]arene 1 with a giant cavity size of 18.769 Å in width and 17.109 Å in height is reported. 1 exhibits highly selective binding of pagoda[5]arene compared to pillar[5]arene and prism[5]arene. Size matching and charge transfer interactions play a key role in the formation of the ring-in-ring stable complex.

Recent advances in the synthesis and applications of macrocyclic arenes

Macrocyclic arenes including calixarenes, resorcinarenes, cyclotriveratrylene, pillararenes and so on have emerged as highly attractive synthetic macrocyclic hosts due to their unique structures, facile functionalization, and broad range of applications. In recent years, there has been growing interest in the development of novel macrocyclic arenes composed of various aromatic building blocks bridged by methylene groups, which have found applications in various research areas. Consequently, the development of novel macrocyclic arenes has become a frontier and hot topic in supramolecular and macrocyclic chemistry. In this review, we feature the recent advances in the synthesis and applications of novel macrocyclic arenes that have emerged in the last decade. The general synthetic strategies employed for these macrocyclic arenes are systematically summarized, and their wide applications in molecular recognition and assemblies, molecular machines, biomedical science and functional materials are highlighted.

Biphen[n]arenes: Modular Synthesis, Customizable Cavity Sizes, and Diverse Skeletons

Macrocyclic compounds are fundamental tools in supramolecular chemistry and have been widely used in molecular recognition, biomedicine, and materials science. The construction of new macrocycles with distinctive structures and properties would unleash new opportunities for supramolecular chemistry. Traditionally popular macrocycles, e.g., cyclodextrins, calixarenes, cucurbiturils, and pillararenes, possess specific cavities that are usually less than 10 Å in diameter; they are normally suitable for accommodating small- or medium-sized guests but cannot engulf giant molecules or structures. Furthermore, the skeletons of traditional macrocycles are impoverished and incapable of being changed; functional substituents can be introduced only on their portals.Thus, it is very challenging to construct macrocycles with customizable cavity sizes and/or diverse backbones. We have developed a versatile and modular strategy for synthesizing macrocycles, namely, biphen[n]arenes (n = 3-8), based on the structure- or function-oriented replacement of reaction modules, functional modules, and linking modules. First, two reaction modules and one functional module are connected by Suzuki-Miyaura coupling to obtain a monomer having two reaction sites. Then Friedel-Crafts alkylation between the monomer and an aldehyde (linking module) serves to afford diversely functionalized macrocycles. Moreover, large macrocycles can be achieved by using long and rigid oligo(para-phenylene) monomers. Because of the modular synthesis and plentiful molecular supplies, the biphen[n]arenes showed interesting recognition properties for both small molecules and large polypeptides. Customizable functional backbones and binding sites endowed this new family of macrocycles with peculiar self-assembly properties and potential applications in gas chromatography, pollutant capture, and physisorptive separation. Biphen[n]arenes would be a promising family of workhorses in supramolecular chemistry.In this Account, we summarize our recent work on the chemistry of biphen[n]arenes. We introduce their design and modular synthesis, including systematic exploration for reaction modules, customizable cavity sizes, skeleton functionalization, pre- and postmodification, and molecular cages. Thereafter, we discuss their host-guest properties, involving the binding for small guests by cationic/anionic/neutral biphen[n]arenes, as well as the complexation of polypeptides by large quaterphen[n]arenes. In addition, we outline the self-assembly and potential applications of this new family of macrocycles. Finally, we forecast their further development. The chemistry of biphen[n]arenes is still in its infancy. Continued exploration will not only further expand the supramolecular toolbox but also open new avenues for the use of biphen[n]arenes in the fields of biology, pharmaceutical science, and materials science.

Fullerene-containing pillar[n]arene hybrid composites

The construction and application of fullerene-containing pillar[n]arene organic–inorganic hybrid composites/systems has been discussed and summarized.