Pagoda[5]arene: An Emerging Anthracene-Based Macrocyclic Arene with a Deep and Well-Defined Cavity

Fluorescent Macrocyclic Arenes: Synthesis and Applications

Fluorescent macrocyclic arenes have attracted increasing interest in macrocyclic and supramolecular chemistry due to their exceptional photophysical properties and versatile applications. Classical macrocyclic arenes modified with fluorescent groups at the upper or bottom rims have long provided valuable platforms across various fields. Recently, a large number of novel fluorescent macrocyclic arenes directly composed of polycyclic aromatic or heteroaromatic building blocks including naphthalene, anthracene, tetraphenylethene, pyrene, fluorene, carbazole, acridan, phenothiazine, coumarin, triphenylamine, benzothiadiazole and so on, have been reported, and they have shown specific fluorescent property, and also exhibited broad applications in molecular recognition, sensing, bioimaging and functional materials. In this review, we focus on the recent advances in the synthesis and applications of fluorescent macrocyclic arenes containing polycyclic aromatic or heteroaromatic skeletons emerged in the past decade. By categorizing these fluorescent macrocyclic arenes based on the different building blocks, this review provides a comprehensive summary of their synthesis, properties and applications.

One-step Macrocycle-to-Macrocycle Conversion Towards Two New Macrocyclic Arenes with Different Structures and Properties

Two new macrocyclic arenes H1 and H2 were conveniently synthesized by the one-step reaction of carboxylic acid substituted octopus[3]arene. It was found that H1 was composed of three ethenoanthracene subunits with a rigid hexagonal structure and H2 contained two ethenoanthracene subunits and one anthracene subunit with a rigid house-shaped structure. Among them, H2 exhibited strong blue fluorescence due to the existence of an anthracene subunit. Moreover, both H1 and H2 showed large and electron-rich cavities, which enable them to effectively complex different nitrogen-containing heterocyclic salt guests in solution and the solid state. It was further found that H2 exhibited stronger complexation towards the tested guests than H1 probably due to the stronger charge-transfer interactions between H2 and the guests.