Iterative synthesis, structures, and properties of acyclic and cyclic acridone oligomers

Abstract

Acyclic and cyclic acridone‐2,7‐diyl oligomers were synthesized by an iterative procedure from 10‐mesitylacridone as heteroatom containing π‐conjugated compounds. The oligomeric chain was elongated by a combination of regioselective bromination, borylation, Ni(0)‐mediated homocoupling, and Suzuki‐Miyaura coupling up to acyclic hexamer. Subsequently, the cyclic hexamer was synthesized by the bromination and intramolecular coupling of the acyclic hexamer. The DFT calculations revealed that the acyclic oligomers preferred to take extended structures with anti conformations, whereas the cyclic hexamer took a macrocyclic structure with syn conformations. The UV/Vis and fluorescence spectra of the series of oligomers were measured, and the effects of the chain length and the cyclization are discussed in terms of π‐conjugation.

Synthesis, Structures, and Complexation with Phenolic Guests of Acridone‐Incorporated Arylene–Ethynylene Macrocyclic Compounds

“…We adopted 10‐mesitylacridone unit 1 to improve the solubility. The Sonogashira coupling of 2 , prepared by the known method, [10] with (trimethylsilyl)ethyne afforded compound 3 , which was then desilylated with tetrabutylammonium fluoride (TBAF) to give terminal alkyne 4 . Reference compound 5 having two phenylethynyl groups was prepared by the Sonogashira coupling of 3 with bromobenzene.…”

“…9.1 Å). [10] In the crystal, molecules form nearly fully stacked dimeric pairs at a separation of 2.96 Å (Figure 2b). The two molecules rotate by 36°each other along the axis passing through their centroids.…”

“…Acridone units have been intelligently applied for the design of functional molecular cages for various guest species by Clever and the coworkers [9] . Recently, we reported the synthesis of acyclic and cyclic acridone‐2,7‐diyl oligomers starting from 10‐mesitylacridone ( 1 ) by an iterative procedure [10] . We herein designed macrocycles C3 , where three acridone units were incorporated into the 1,3‐phenylene–ethynylene cyclic hexamer structure at alternating positions.…”

“…[9] Recently, we reported the synthesis of acyclic and cyclic acridone‐2,7‐diyl oligomers starting from 10‐mesitylacridone ( 1 ) by an iterative procedure. [10] We herein designed macrocycles C3 , where three acridone units were incorporated into the 1,3‐phenylene–ethynylene cyclic hexamer structure at alternating positions. Because the three carbonyl groups direct toward the macrocyclic center, the cavity should be surrounded by an electron‐rich region and interacting sites.…”