Dimeric Cycloparaphenylenes with a Rigid Aromatic Linker

Abstract

Dimeric cycloparaphenylene (CPP) architectures with well-defined flipping motion are constructed taking advantage of an efficient cyclocondensation reaction. Variable-temperature nuclear magnetic resonance (VT-NMR) analyses and theoretical calculations indicate rapid interconversion of cis and trans conformers at room temperature, while energetically favorable trans conformer exists at low temperature with the metastable cis conformer hidden. The trihexylsilylethynyl-substituted dimer exhibits bright emission in solution at 616 nm with quantum yield up to 80 %, representing the brightest CPP-based emitter beyond 600 nm. A 1:2 hostguest complex of the dimer and C 60 is established with negative cooperativity, demonstrating the first example of 1:2 complex from CPP derivatives.

A Highly Strained All‐Phenylene Conjoined Bismacrocycle

“…Moreover, the negative cooperativity (4 K 2 / K 1 <1) phenomenon revealed that the binding of the first equivalent PCBM decreases the rate of subsequent binding, which presumably results from the change of electronic effect after the first binding. A similar observation was also reported in two fullerene‐based supramolecular complex [13c] . Further studies of the mechanism and the solid‐state structures will be meaningful for supramolecular chemistry.…”

“…Other examples incorporating 9,9'-bicarbazole, 9,9'-spirobifluorene, or fused polycyclic aromatic scaffold subunits have been recently synthesized and investigated. [13] Benzene is an aromatic molecule that possesses many representative structures and properties of aromaticity, such as substantial energy stabilization, planarity, bond length equalization, and typical spectroscopic features. [14] Intriguingly, the benzene exhibits conformational ring flexibility and chemical stability even if it suffers severe distortion.…”

“…In previous studies, the bismacrocycles were synthesized from central cores. [10,11,13] Inspired by these reports, we tried to start our synthesis from 1,2,4,5tetrasubstituted benzene. However, after many attempts, no target product can be obtained; an alternate design is needed to initially obtain one functionalized macrocycle.…”

Recent Advances in Dimeric Cycloparaphenylenes as Nanotube Fragments

“…These molecular systems, in their cis-conformation, can be regarded as nitrogen-doped nanotube fragments. 27…”

Cycloparaphenylene–Phenalenyl Radical and Its Dimeric Double Nanohoop**

“…Notably, CPP-PP represents a fully p-conjugated hydrocarbon framework made of 158 sp 2 -carbon atoms as a novel member of CPP architectures that feature multiple nanoring cycles. [23][24][25][26][27] The pivotal intermediate in our synthetic strategy was nanoring 1 (Scheme 1), formed by one dihydrophenalenone unit and 11 phenylene rings. It was synthesized via Suzuki-Miyaura cross-coupling macrocyclization of dihydrophenalenone 2 and C-shaped linker 3.…”