Systematic Synthesis of Tetrathia[8]circulenes: The Influence of Peripheral Substituents on the Structures and Properties in Solution and Solid States

Abstract

We developed the diversity-oriented approach for the synthesis of tetrathia [8]circulenes with a variety of peripheral substituents. Iridium-catalyzed direct C−H borylation of tetrathienylene provided 1,4,7,10-tetraboryltetrathienylene as a major product. 1,4,7,10-Tetraboryltetrathienylene served as an a key intermediate to achieve the selective synthesis of octasubstituted or tetrasubstituted tetrathia[8]circulenes via rhodium-catalyzed annulation with symmetric internal alkynes or sequential Sonogashira−Hagihara coupling and base-promoted intramolecular cyclization. A variety of substituents were installed at the peripheral positions of tetrathia[8]circulenes systematically. The self-assembling behavior of tetrathia[8]circulenes was investigated using 1 H NMR and AFM measurements. The number and the chain length of alkyl groups exerted a significant influence on the aggregation ability and the crystal packing structures of tetrathia [8]circulenes in both solution and solid states. We also found that the molecular arrangement of the self-assembled tetrathia[8]circulene molecules affected the hole mobility assessed by the FP-TRMC method.

Enthalpically and Entropically Favorable Self‐Assembly: Synthesis of C4h‐Symmetric Tetraazatetrathia[8]circulenes by Regioselective Introduction of Pyridine Rings

“…The sums of the inner angles of the central eight‐membered ring are 1079.94° in C and 1079.96° in D , which are close to that of a regular octagon (1080°). These results demonstrate the highly planar structure of 1 a , which is similar to that of the carbon analogue 2 b [9e] . The eight C−C bonds in the central eight‐membered ring of 1 a (1.427(7)–1.465(7) Å) are substantially longer than that of a typical C=C double bond.…”

“…We also evaluate the effect of the introduced pyridine moieties compared with properties of tetrathia[8]circulenes 2 as the carbon analogues (Figure 1 c). [9e] Until now, examples of hetero[8]circulenes have been limited to circulenes with five‐membered heterocycles such as furan, pyrrole, thiophene, selenophene, silole, and germole [9–14] . Thus, tetraazatetrathia[8]circulenes 1 represent a novel class of [8]circulenes with hexagonal heterocycles.…”

Aggregation‐Induced Emission in Tetrathia[8]circulene Octaoxides via Restriction of the Dynamic Motion of their Negatively Curved π‐Frameworks

“…Hetero [8]circulenes are [8]circulenes that contain heteroaromatic rings. [6][7][8][9][10][11][12][13] The introduction of heteroatoms significantly affects the structural, photophysical, and electrochemical properties of [8]circulenes. Previously, electron-donating hetero [8] circulenes that contain furan, thiophene, selenophene, and pyrrole have been synthesized (Figure 1b).…”

“…Previously, electron-donating hetero [8] circulenes that contain furan, thiophene, selenophene, and pyrrole have been synthesized (Figure 1b). [6][7][8][9][10][11] Herein, we report the synthesis of electron-accepting tetrathia[8]circulenes octaoxides 1 a-1 d and their AIE behavior, which originates from the restriction of the dynamic motion of their negatively curved πframeworks in the solid state (Figure 1c).…”

Improved Synthesis of ortho‐Phenylene‐bridged Cyclic Tetrapyrroles and Oxidative Fusion Reactions Toward Substituted Tetraaza[8]circulenes

“…The structures, solid‐state packings, and optical properties are studied with a focus on their substituent effects. Since peripheral functionalization of hetero[8]circulenes have been very rare and only symmetric alkylation at the periphery and N‐alkylation of aza[8]circulene are known, [8b,d,14] this work paves the way to study the structure‐property relationship of hetero[8]circulenes more in detail.…”