Fully conjugated π-expanded macrocyclic oligothiophenes with 24π to 180π electron systems have been synthesized using a modified McMurry coupling reaction as the key step. For the synthesis of cyclo[ n ](2,5-thienylene-ethynylene)s composed of thiophenes and acetylenes, bromination-dehydrobromination and double elimination procedure were employed. X-ray analyses of macrocyclic oligothiophenes with 24π, 60π, and 72π systems revealed unique molecular and packing structures, reflecting planar cyclic frameworks with medium to large inner cavities. All the giant macrocycles exhibit multistep reversible redox behavior with a fairly low first-oxidation potentials, reflecting their cyclic conjugation. The doping of macrocycles with iodine forms semiconductors owing to their π-donor properties and π–π stacking ability. Interestingly, 90π, 108π, and 120π systems self-aggregate in the solid state to form red nanofibers or petal structure, whereas 150π to 180π systems form red nanoparticles. The structures of fibrous aggregates and particles have been established by scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses. Furthermore, two-photon properties of 72π, 108π, 144π, and 180π systems show that the increasing π-conjugation leads to an increase in the two-photon absorption cross-section with magnitudes as high as 100 000 GM in the visible spectral region.

Masahiko Iyoda

Pure and Applied Chemistry

PURE AND APPLIED CHEMISTRY 是 IUPAC 的官方月刊，负责出版由联盟赞助和承担的国际科学活动和项目产生的作品。政策是在纯化学和应用化学各个方面的前沿发表具有高度话题性和可信度的作品，随之而来的目标是促进该期刊被广泛接受，作为学术和机构图书馆中权威和不可或缺的藏品。

Pure and Applied Chemistry is the official monthly journal of the International Union of Pure and Applied Chemistry (IUPAC), responsible for publishing works resulting from international scientific activities and projects sponsored and undertaken by the union. The journal's policy is to publish highly topical and credible works at the forefront of pure and applied chemistry, with the goal of promoting the journal's wide acceptance as an authoritative and indispensable collection in academic and institutional libraries.

《Pure and Applied Chemistry》是国际纯粹与应用化学联合会（IUPAC）的官方月刊，负责出版由联盟赞助和承担的国际科学活动和项目所产生的研究成果。期刊的政策是发表在纯化学和应用化学各个领域具有高度话题性和可信度的作品，旨在促进该期刊被广泛接受，成为学术界和机构图书馆中权威且不可或缺的藏品。

Category	Quartile
化学	4
化学, 化学综合	4

Fully conjugated macrocycles composed of thiophenes, acetylenes, and ethylenes

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Journal Info

Category	Quartile
CHEMISTRY, MULTIDISCIPLINARY	3