From a one-pot nickel-mediated Yamamoto-type coupling reaction of m-dibromobenzene, five congeners of [n]cyclo-meta-phenylenes were synthesized and fully characterized. The [n]cyclo-meta-phenylenes possessed a commonly shared arylene unit and intermolecular contacts but varied in packing structures in the crystalline solid state. Columnar assembly of larger congeners yielded nanoporous crystals with carbonaceous walls to capture minor protic or aliphatic solvent molecules. The concise and scalable synthesis allowed exploration of the macrocyclic hydrocarbons as bipolar charge carrier transport materials in organic light-emitting diode devices.
Mothball macrocycles: Naphthalene has been coupled to form macrocylic oligomers composed of five, six, and seven naphthalene units (see picture). Thermally stable macrocycles bearing 50, 60, or 70 π electrons within the hydrocarbon structure form columnar assemblies in crystals and serve as bipolar carrier transport materials in organic light‐emitting diode devices.
A method for the modular synthesis of aromatic hydrocarbon macrocycles has been developed for base materials in single-layer organic light-emitting devices. The method with Ir-catalyzed direct C-H borylation and Suzuki-Miyaura coupling was concise and scalable, which allowed for a gram-scale preparation of aromatic hydrocarbon macrocycles that have bulky substituents at the periphery. The new arylated hydrocarbon macrocycles enabled a quantitative electro-optical conversion in organic light-emitting devices with a phosphorescent emitter, which is, notably, in a single-layer architecture consisting of two regions of doped and undoped materials. The highest external quantum efficiencies reached 24.8%, surpassing those of previous hydrocarbon base materials.
Mottenkugel‐Makrocyclen: Naphthalin wurde zu makrocylischen Oligomeren aus fünf, sechs und sieben Naphthalineinheiten gekuppelt (siehe Bild). Die thermisch stabilen Makrocylen mit 50, 60 oder 70 π Elektronen in reinen Kohlenwasserstoffen bilden im Kristall säulenförmige Assoziate und dienen als bipolare Transportmaterialien für Träger in organischen Leuchtdioden.
Single crystals of a macrocyclic hydrocarbon, [6]cyclo-2,7-naphthylene ([6]CNAP, C60H36) were prepared from anthracene melt with a prolonged time for the recrystallization. The crystal of improved quality led to the correction of the space-group assignment to Cmca from in the original determination [Nakanishi et al. (2011 ▶) Angew. Chem. Int. Ed.
50, 5323–5326] and the refinement of anisotropic displacement parameters of all C atoms. The refined molecular structure with C
2h point symmetry indicated that the strain on the naphthyl rings of [6]CNAP is smallest among the congeners. Despite the large macrocyclic structure, molecules are packed in a ubiquitous herringbone motif. A short C—C distance of 3.119 (4) Å was found in the stacking direction, and a short C—H distance of 2.80 Å was found in the intercolumnar contact.
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