Triptycene-Derived Macrocyclic Arenes: From Calixarenes to Helicarenes

Abstract

The development of new types of synthetic macrocyclic hosts is always one of the most important and attractive topics in macrocyclic and supramolecular chemistry. Calixarenes, resorcinarenes, cyclotriveratrylenes, pillararenes, and their analogues are all composed of hydroxy-substituted aromatic rings bridged by methylene or methenyl groups and thus can be considered a type of macrocyclic arenes. Because of their unique structural features, easy functionalization, and wide applications in many research areas, such macrocyclic arenes have become some of the most important and studied synthetic macrocyclic hosts during the last decades. Triptycene and its derivatives are a class of organic molecules having unique three-dimensional rigid structures, and they have proved to be useful building blocks for constructing new synthetic macrocyclic hosts with specific structures and properties. Dihydroxy-substituted triptycene derivatives are readily available compounds, which encouraged us to conduct studies of triptycene-derived macrocyclic arenes about 10 years ago. Consequently, a series of triptycene-derived calixarenes and analogues containing 1,8-dihydroxy-substituted triptycene subunits were conveniently synthesized. With 2,7-dihydroxy-substituted triptycene as a precursor, new types of calixarene, oxacalixarene, and homooxacalixarene analogues were also obtained. These triptycene-derived macrocyclic hosts all showed fixed conformations in solution and exhibited expanded cavities compared with the corresponding typical calixarenes and analogues. The special structural features also make these triptycene-derived macrocycles show wide potential applications in molecular recognition and self-assembly. In particular, it was found that the threading direction and the orientation based on macrocycles with nonsymmetric structures could be finely controlled by adjusting the electrostatic and steric effects of the guests, which could form the oriented [2]rotaxane by unidirectional threading. We recently developed a new kind of chiral macrocyclic arenes named helicarenes that are composed of chiral 2,6-dihydroxy-substituted triptycene subunits bridged by methylene groups. It was found that the helicarenes not only exhibited convenient synthesis, high stability, good solubility, fixed conformations, and easy functionalization but also showed complexation abilities with various chiral and achiral organic guests. In particular, the switchable complexation based on these macrocycles could be efficiently controlled by multiple stimuli, including acid/base, redox, anion, or light stimuli under a photoacid. Moreover, the helicarenes have also found applications in the construction of interlocked molecules and molecular machines. This Account summarizes our recent research results on the synthesis and structures of the triptycene-derived macrocyclic arenes and analogues and their applications in host-guest chemistry and molecular assembly. We believe that these macrocyclic arenes, especially helicarenes, could be utilized as new synt...

Effect of Chirality on the Binding of Viologen Guests in Porphyrin Macrocycles

“…Furthermore, we show that ( R , S p * )‐ H 2 4 and ( R , R p * )‐ H 2 5 have different affinities for chiral viologen guest molecules. (for recent other chiral cage compounds, see refs …”

“…NMR (126 MHz,[D 3 ]acetonitrile) δ 150.81(12), 146.59 (10), 128.17(11), 61.64 (1), 39.83(7), 39.13 (2), 37.48 (5), 31.28(3), 28.71 (8), 25.25 (6), 22.93 (9), 22.83 (9), 19.48 (4). HRMS (m/z): [M -PF 6 ] + calcd.…”

Prismarene: An Emerging Naphthol‐Based Macrocyclic Arene

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“…Another feature of these macrocycles is that they are fluorescent and may be used as fluorescent sensors. [11] In view of the successes achieved with phenol-based macrocyclic arenes, [2,3,14] it can be anticipated that there will be ab right future for prism-[n]arenes.…”

Synthesis of Distorted 1,8,13‐Trisilyl‐9‐hydroxytriptycenes by Triple Cycloaddition of Ynolates to 3‐Silylbenzynes

“…The 1,8,13-trihalogenatedt riptycenes were then converted to 1,8,13-functionalized triptycenes. Triptycenei sarigid and symmetric propeller shaped organic molecule with ab icyclo [2.2.2]octatriene skeleton. [1] Because of these special properties,t riptycenes have been used as basic units of host molecules in the field of molecularr ecognition, [2] supramolecular chemistry, [3] macromolecules, [4] materials ciences, [5] and metal ligands. [6] However, functionalized triptycenes are not easily obtained because major synthetic methodsf or triptycenes are limited to cycloaddition of benzyne [7] or benzoquinone [8] to anthracenes.…”