Complexation of an Anthracene‐Triptycene Nanocage Host with Fullerene Guests through CH⋅⋅⋅π Contacts

Abstract

A bicyclic anthracene macrocycle containing two triptycene units at the bridgehead positions was synthesized by Nimediated coupling of the corresponding precursor as a cageshaped aromatic hydrocarbon host. This cage host formed an inclusion complex with C 60 or C 70 guest in 1 : 1 ratio in solution. The association constants (K a ) determined by the fluorescence titration method were 1.3 × 10 4 and 3.3 × 10 5 L mol À 1 for the C 60 and C 70 complexes, respectively, at 298 K in toluene. DFT calculations revealed that the guest molecules were included in the middle of the cavity with several CH•••π contacts. The strong affinity of the cage host for the fullerene guests and the high selectivity toward C 70 are discussed on the basis of spectroscopic and structural data.

A Chiral Molecular Cage Comprising Diethynylallenes and N‐Heterotriangulenes for Enantioselective Recognition

“… [3] Such chiroptical sensors comprise a more or less open cavity, in which the higher the number of interactions between host and guest, the higher the specificity of the recognition event. [4] To this regard, 3D cage cavities are theoretically preferred over macrocyclic ones, [5] with size and shape being key factors to consider for an accurate chiral matching. Strategies to achieve chiral cages involve either the assembly of achiral units in a chiral fashion, often leading to statistic mixtures, or the direct use of enantiopure chiral building blocks.…”

Purely Covalent Molecular Cages and Containers for Guest Encapsulation

“…These authors also did DFT calculations, which showed that several CH•••π contacts played an important role in complex formation and predicted higher interaction energy with C 70 compared to C 60 (Figure 6). 39 Li and co-workers reported the one-pot synthesis of covalent organic cages from 1,3,5-tris(2,4-dimethoxyphenyl)benzene 21 monomer and paraformaldehyde or isobutyraldehyde to yield the dimeric cage 22 with a 52% yield and the tetrameric cage 23 with a 46% yield, respectively. The [2]cage 22 has a cavity composed of three nearly identical buckets with a size of 10.5 Å × 9.4 Å and an additional central cavity of 9.4 Å × 5.7 Å.…”

“…Figure 6. Synthesis of fully aromatic hydrocarbon cage 20 that features two triptycene bridge units 39. …”

Unraveling the Nature and Strength of Non‐Covalent Interactions on the Surface of Fullerenes

“…Toyota et al expanded the molecular design to include the synthesis of bicyclic cage-like macrocycles composed of anthracene components. [44,45] Notably, they synthesized a series of anthracene-based nanocages that featured various electron donating or accepting substituents (13 a, 13 b, 13 c) and compared the K SV values of these compounds with those of C 60 or C 70 through fluorescence titration experiments (see Figure 5). The results revealed that the K SV values decreased in the following order: 13 a (( 22 (110 � 10) × 10 3 L mol À 1 for C 70 ), suggesting that the binding abilities decreased as electron-withdrawing groups were introduced.…”