New advances in nanographene chemistry

Abstract

Nanographenes, or extended polycyclic aromatic hydrocarbons, have been attracting renewed and more widespread attention since the first experimental demonstration of graphene in 2004. However, the atomically precise fabrication of nanographenes has thus far been achieved only through synthetic organic chemistry. The precise synthesis of quasi-zero-dimensional nanographenes, i.e. graphene molecules, has witnessed rapid developments over the past few years, and these developments can be summarized in four categories: (1) non-conventional methods, (2) structures incorporating seven- or eight-membered rings, (3) selective heteroatom doping, and (4) direct edge functionalization. On the other hand, one-dimensional extension of the graphene molecules leads to the formation of graphene nanoribbons (GNRs) with high aspect ratios. The synthesis of structurally well-defined GNRs has been achieved by extending nanographene synthesis to longitudinally extended polymeric systems. Access to GNRs thus becomes possible through the solution-mediated or surface-assisted cyclodehydrogenation, or "graphitization," of tailor-made polyphenylene precursors. In this review, we describe recent progress in the "bottom-up" chemical syntheses of structurally well-defined nanographenes, namely graphene molecules and GNRs.

Complexation and Electronic Communication between Corannulene‐Based Buckybowls and a Curved Truxene‐TTF Donor

“…These two dispositions resemble the arrangement found in the crystal packing for the homodimers of truxTTF and the related C 30 H 12 , implying a mixture of p-p and CH-p interactions. [30,32] All the optimized heterodimeric structures (1)(2)(3)(4) show close intermolecular contacts in the 2.5-3.7 range ( Figure S1 in the Supporting Information), indicative of stabilizing noncovalent interactions between both bowls.…”

“…[1][2][3] If PAHs are formed solely by fused benzene rings, their structure remains planar, except in helicenes [4][5][6] or highly strained cyclic derivatives, [7][8][9][10][11] whereas PAHs featuring five-membered rings as part of their structure adopt nonplanar equilibrium geometries. In an extreme scenario, spherical fullerenes evolve upon embedding twelve five-membered rings into a PAH structure.…”

Tailoring Colors by O Annulation of Polycyclic Aromatic Hydrocarbons

“…Bottom‐up covalent synthesis can be exploited to access structurally defined heteroatom‐doped graphene fragments with precise control over the size, periphery, substitution pattern, doping ratio, and position 36, 37. In this respect, peri ‐xanthenoxanthene (PXX),38, 39 the O‐doped analogue of anthanthrene, can be conceptualized as a building unit for engineering a new class of O‐doped PAHs.…”

An Electron‐Poor C64 Nanographene by Palladium‐Catalyzed Cascade C−C Bond Formation: One‐Pot Synthesis and Single‐Crystal Structure Analysis

“…The conventional synthetic strategies for the construction of such PAHs, including heteroatom‐containing electron‐rich graphene‐type molecules, such as annulated porphyrins,6 are based on pioneering work by Scholl7 and Clar,8 and usually include common C−C bond‐formation steps, such as Suzuki–Miyaura or Yamamoto cross‐couplings, Diels–Alder cycloadditions, or acetylene trimerizations, to prepare the polyaromatic precursors. To ultimately annulate these multiaromatic building blocks for the construction of fully π‐conjugated scaffolds, the final carbon–carbon bonds are commonly generated by oxidative dehydrogenation using Lewis acids or oxidants such as FeCl 3 , MoCl 5 , or DDQ in Scholl‐type coupling reactions 4a, 9…”