per-Hydroxylated Prism[n]arenes: Supramolecularly Assisted Demethylation of Methoxy-Prism[5]arene

Supramolecular Exchange Reaction in the Cavity of Naphthalene Diimides Extended-Pillar[6]arene

A new naphthalene diimides extended-pillar[6]arene 1 with a large cavity and rich host-guest complexation properties was synthesized in high yield. It can not only form 1 : 2 complexes with large size polycyclic aromatic hydrocarbons but also form 1 : 1 : 1 ternary complex with perylene and 2,7-diazapyrenium. Moreover, the supramolecular exchange reaction from a 1 : 2 host-guest complex 1 ⋅ (G3)2 formed by 1 and perylene to a 1 : 1 : 1 ternary complex 1 ⋅ G3 ⋅ G5 formed by 1 with perylene and 2,7-diazapyrenium salt was also investigated by 1H NMR experiments as well as theoretically calculations.

Thermodynamically Templated Macrocyclizations: Enhancing the Synthesis of Prism[5]arenes with Tailor-Made Guests

The macrocyclization of 2,6-dialkoxynaphthalene monomers to prism[5]arenes is thermodynamically templated by DABCO cations. In this study, we demonstrate that a greater template affinity for prism[5]arene improves the macrocyclization yield. By using novel templating cations, the yield of alkoxy-prism[5]arenes increases significantly compared with those of previously reported procedures, while the purification process becomes easier and faster.

Under the Influence of Water: Molecular Recognition of Organic Hydrophilic Molecules in Water with a Prismarene Host Driven by Hydration Effects

A water-soluble prism[5]arene host can form endo-cavity complexes with hydrophilic organic substances in water by displacing frustrated water molecules from its deep cavity. Water molecules structured at both rims of the prismarene host can mediate hydrogen bonding interactions with the guest. Water-mediated hydrogen bonding interactions were invoked here to elucidate the elevated binding affinities and selectivity of the prismarene host toward hydrophilic organic guests. We show that water at the interface of a host-guest complex can act as an extension of the host structure, facilitating the accommodation of neutral guests within the binding site. This study highlights the crucial role of water in facilitating supramolecular interactions between a deep-cavity prismarene host and organic hydrophilic guests in aqueous medium.

Construction of hydrocarbon belts based on macrocyclic arenes

Hydrocarbon belts have garnered significant attention due to their intriguing structures, unique properties, and potential applications in supramolecular chemistry and materials science. However, their highly inherently strained structures pose challenges in their synthesis, and the resulting tedious synthesis strategies hinder their large-scale applications. Utilizing unstrained macrocyclic arenes as precursors presents an efficient strategy, allowing for a strain-induction step that mitigates the energy barrier associated with building strain in the formation of these belts. Accessible unstrained macrocyclic precursors play a pivotal role in enabling efficient and large-scale syntheses of highly strained belts, facilitating their broader practical applications. This review provides an overview of the recent advancements in the construction of hydrocarbon belts using accessible macrocyclic arenes as building blocks. The synthetic strategies for these partially and fully conjugated hydrocarbon belts are discussed, along with their unique properties. We hope that this review will inspire the development of novel nanocarbon molecules, opening pathways for emerging areas and applications.

Chirality Sensing of Cryptochiral Guests with Prism[n]arenes

Optical chirality sensing has gained significant attention in recent years. Within this field, the quest for stereodynamic chiroptical probes capable of detecting cryptochiral guests presents a formidable challenge. Macrocycles exhibiting planar chirality have emerged as promising candidates for amplifying the chirality of cryptochiral guests. In this study, we demonstrate that the formation of host-guest complexes between cryptochiral molecules and planar chiral prismarenes triggers electronic circular dichroism (ECD) signals via host-guest complexation-induced chirality amplification. The absolute configuration of the most stable chiral macrocyclic host-guest complex has been established by resorting to both exciton model and DFT computations. Furthermore, we demonstrated that this supramolecular chirality sensing system can be employed to determine the enantiomeric composition of scalemic mixtures by measuring the ECD bands intensity. The information described here opens the way for the use of prismarenes as stereodynamic probes for sensing of cryptochiral guests.

Charge-transfer inclusion complex formation of the tropylium cation with prism[6]arenes

Herein, we report that prism[6]arenes (PrS[6]R) can form charge-transfer (CT) inclusion complexes with tropylium tetrakis[3,5-bis(trifluoromethyl)-phenyl]borate (G) in chloroform solution with an obvious CT band at 560 nm. Moreover, the CT complex PrS[6]Et⊃G showed Cl-/Ag+ responsiveness which can be easily monitored by the naked eye.

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.

Confused-Prism[5]arene: a Conformationally Adaptive Host by Stereoselective Opening of the 1,4-Bridged Naphthalene Flap

The confused-prism[5]arene macrocycle (c-PrS[5]^Me ) shows conformational adaptive behavior in the presence of ammonium guests. Upon guest inclusion, the 1,4-bridged naphthalene flap reverses its planar chirality from pS to pR (with reference to the pS(pR)₄ enantiomer). Stereoselective directional threading is also observed in the presence of directional axles, in which up/down stereoisomers of homochiral (pR)₅ -c-PrS[5]^Me pseudorotaxanes are formed.

"Rim-Differentiated" Pillar[6]arenes

A "rim-differentiated" pillar[6]arene (RD-P[6]) was obtained successfully, with the assistance of a dimeric silver trifluoroacetate template, among eight different constitutional isomers in a direct and regioselective manner. The solid-state conformation of this macrocycle could switch from the 1,3,5-alternate to a truly rim-differentiated one upon guest inclusion. This highly symmetric RD-P[6] not only hosts metal-containing molecules inside its cavity, but also can form a pillar[6]arene-C₆₀ adduct through co-crystallization on account of donor-acceptor interactions. The development of synthetic strategies to desymmetrize pillararenes offers new opportunities for engineering complex molecular architectures and organic electronic materials.

Molecular Recognition in an Aqueous Medium Using Water-Soluble Prismarene Hosts

The synthesis of water-soluble prism[n]arenes (n = 5 and 6) bearing anionic carboxylato groups on the rims is described. The binding properties of this novel class of water-soluble hosts are studied by nuclear magnetic resonance and calorimetry. The complexation of singly and doubly charged ammonium guests with the more rigid pentamer is enthalpically driven by secondary interactions, while the thermodynamic fingerprint for the larger hexamer reveals driving forces that strongly depend on the guest charge and/or size.