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The phenylene segments of CNTs, taking armchair CNT(9, 9), zigzag CNT(9, 0), and CNT(11, 0) as examples. CNT(n, m) can be unzipped into a graphene sheet defined by a vector [V(n, m)]
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Well-studied cycloparaphenylenes (CPPs) correspond to the simplest segments of armchair CNTs, whereas the corresponding macrocyclic oligophenylene strip of zigzag CNTs is still missing. Herein, we present two series of conjugated macrocycles (CM2PP and CN2PP) containing two meta-phenylene or 2,7-naphthylene units facing each other in the strip. CM2...
Citations
Cyclic anthraquinodimethane (AQD) dimer with a highly constrained structure was synthesized by using the Au-templated method. X-ray diffraction analysis and UV-Vis spectroscopy revealed that the AQD skeleton adopts a deeply folded structure and exhibits red-shifted absorptions in the dimer compared to those in non-cyclized monomeric AQD. Due to the rigid and constrained structure, both enantiomers of the cyclic AQD dimer with planar chirality can be isolated and show strong circular dichroism signals. It is demonstrated that the Au-templated method is a valuable way to access a highly constrained cyclic structure with AQD skeletons.
Carbon nanotubes (NTCs) represent one of the most intriguing and promising structures in the field of nanotechnology and materials science. Discovered in the 1990s, these hollow graphitic carbon cylinders possess unique mechanical, electrical, thermal, and chemical properties that make them suitable for a wide range of applications. Since their discovery, NTCs have revolutionized nu-merous fields, including electronics, medicine, materials engineering, and energy. The importance of NTCs lies not only in their exceptional properties but also in their potential to drive future tech-nological innovations. This monograph focuses on exploring the multifaceted nature of carbon nanotubes, covering their discovery, unique properties, synthesis methods, functionalization, ap-plications, and current challenges. The main objective is to provide an in-depth understanding of NTCs and highlight their transformative impact in various scientific and technological areas.
To investigate the host ability of a simple macrocycle, 1,3-phenylene-bridged naphthalene hexamer N6, we evaluated the complexation of N6 with fullerenes in toluene and in the crystals. The complexes in the solid-state demonstrate the one-dimensional alignment of fullerenes. The single-crystals of the C60@N6 composite have semiconductive properties revealed by photoconductivity measurements.
Carbon nanorings (CNRs) and carbon nanobelts (CNBs) of various sizes and innovative molecular architectures have ushered improvement in research in recent years. This serves as a prerequisite for further advances and applications, such as organic semiconductors and bottom‐up synthesis of single‐walled carbon nanotubes. Nevertheless, challenges such as high strain energy, excessive reactivity, end‐product stability, low‐scale yields, and side reactions inhibit material synthesis and applications. In this review, CNRs, CNBs, and other heteroatom‐doped molecular belts are discussed based on their molecular structural characteristics, with a special focus on their developments in the past two years. Furthermore, current applications, research obstacles, and future developments related to CNRs and CNBs are discussed. For the first time, studies and advancements in organic field‐effect transistors (OFETs) have been summarized in detail.
A stable nanohoop radical (OR3) combining the structures of cycloparaphenylene and an olympicenyl radical is synthesized and isolated in the crystalline state. X‐ray crystallographic analysis reveals that OR3 forms a unique head‐to‐tail dimer that further aggregates into a one‐dimensional chain in the solid‐state. Variable‐temperature NMR and concentration‐dependent absorption measurements indicates that π‐dimer is not formed in solution. An energy decomposition analysis indicates the van der Waals interactions are the driven force for the self‐association process, in contrast with other olympicenyl derivatives that favor π‐dimerization. The physical properties in solution phase are studied, and stable cationic species is obtained via one‐electron chemical oxidation. This study puts forth a new molecular design to modulate the self‐association of organic radicals for overcoming spin‐Peierls transition, and to prepare novel nanohoop compounds with spin‐related properties.
A stable nanohoop radical (OR3) combining the structures of cycloparaphenylene and an olympicenyl radical is synthesized and isolated in the crystalline state. X‐ray crystallographic analysis reveals that OR3 forms a unique head‐to‐tail dimer that further aggregates into a one‐dimensional chain in the solid state. Variable‐temperature NMR and concentration‐dependent absorption measurements indicate that the π‐dimer is not formed in solution. An energy decomposition analysis indicates that van der Waals interactions are the driving force for the self‐association process, in contrast with other olympicenyl derivatives that favor π‐dimerization. The physical properties in solution phase have been studied, and the stable cationic species obtained by one‐electron chemical oxidation. This study offers a new molecular design to modulate the self‐association of organic radicals for overcoming the spin‐Peierls transition, and to prepare novel nanohoop compounds with spin‐related properties.
Carbon nanohoops compounds have attracted recently extensive attention due to aesthetically pleasing structures and unique properties. In order to reveal structure-property interaction between the size-dependence effect and the nonlinear optical...
The chemistry of nonalternant hydrocarbons has recently experienced a considerable resurgence. As the relationship between naphthalene and azulene shows, an important design concept for a nonalternant framework is to replace the two hexagons of an alternant system with a pentagon and heptagon pair. The pursuit of the nonalternant isomers of pyrene, which has seven possible nonalternant isomers, has been the most significant related project. Through enormous dedication by many pioneering works, six of the seven possible nonalternant isomers of pyrene have been isolated and characterized as stable aromatic molecules, differentiating themselves from pyrene in terms of optoelectronic properties. However, the only unsynthesized isomer, bis‐periazulene (cyclohepta[def]fluorene), had remained an uncharacterized hydrocarbon until 2022, despite many synthetic and theoretical investigations since it was first reported in 1955. In this review, we summarize the chemistry of the pyrene’s nonalternant isomers, including our recent achievements in synthesizing and characterizing bis‐periazulene derivatives. The historical perspectives, synthetic approaches, fundamental properties, and comparisons to related systems are documented.
