Columnar Mesophase Formation of Cyclohexa‐m‐phenylene‐Based Macrocycles

Abstract

Two novel discotic macrocycles, substituted cyclohexa-m-phenylene (CHP) and cyclo-3,6-trisphenanthrylene (CTP), and the linear oligomer 3,3':6',3''-terphenanthrene (TP) as a model substance have been synthesized by repetitive cross-coupling reactions. To correlate the molecular design with the supramolecular architecture and the established macroscopic order, 2D wide-angle X-ray scattering experiments were performed on mechanically extruded filaments. At room temperature in their crystalline phases, all three compounds revealed columnar assemblies in which the macrocycles self-organized by pi-stacking interactions. The degree of macroscopic order was found to depend upon the planarity and stiffness of the aromatic core. The flexible CHP ring showed a poor macroscopic order of the columnar structures and a low isotropization temperature, whereas the more-planar, less-flexible CTP self-assembled into well-defined superstructures. The larger pi-stacking area and the more-pronounced intermolecular interactions for CTP led to the formation of a mesophase over a very large temperature range. The surprising columnar organization of the "open" TP system was explained by back-folding of the molecule into a ringlike structure.

Torands Revisited: Metal Sequestration and Self‐Assembly of Cyclo‐2,9‐tris‐1,10‐phenanthroline Hexaaza Macrocycles

“…The prerequisite for a smoothly occurring cyclotrimerization is a 120° substitution pattern on the molecular building block, as reflected by our previous investigations 21–25. Thus, a five‐step synthetic route from parent 1,10‐phenanthroline ( 1 ) to the target 2,9‐dichloro‐5,6‐dialkoxy‐1,10‐phenanthroline precursors 6 a – c was developed (Scheme ).…”

“…For the cyclotrimerization of precursors 6 a – c towards macrocycles 7 a – c , a standard Yamomoto protocol21–23, 35, 36 was carried out in an overall 3/1 mixture of toluene/DMF at 60 °C under pseudo‐dilution conditions (cf. Scheme , for the proposed reaction pathway towards 7 a – c , see Scheme S2 in the Supporting Information).…”

“…Examples of successful cyclotrimerization reactions involve the copper(II)‐mediated reaction of Grignard reagents derived from biphenyl,16 ortho ‐terphenyl,17 and phenanthrene18, 19 and the trimerization of Lipshutz cuprates 20. We have recently introduced a Yamamoto‐based concept, which relies on the selective assembly of functionalized phenanthrene21, 22 and triphenylene23–25a derivatives to form a new class of C 3 symmetric macrocycles. Lately, this concept was adopted to synthesize a series of quinoxaline‐based cyclo(oligophenylenes) 25b…”

Dehalogenation and Coupling of a Polycyclic Hydrocarbon on an Atomically Thin Insulator

“…The software WSXM was used to analyse the STM images. 39 The DFT calculations were performed using the CP2K package (CP2K version 2.3.43; CP2K is freely available in http://www.cp2k.org/) with the mixed Gaussian and plane wave formalism 40 and periodic boundary conditions. The exchange and correlation functional used was the revised 41 version of the Perdew-Burke-Ernzerhof (PBE) 42 function.…”

Macrocyclic 2,7‐Anthrylene Oligomers

“…In the course of our studies of anthracene–acetylene oligomers, we found that bulky mesityl (Mes) groups on an anthracene unit reasonably improved the solubility and stability because those groups protected the aromatic cores from intermolecular stacking and undesired reactions . These findings inspired us to synthesize [6]CANT*, a [6]CANT analogue having twelve Mes groups at all 9,10‐positions, as a novel cycloarylene consisting of large polycyclic aromatic hydrocarbon (PAH) units . We herein report the synthesis, structure, spectroscopic properties, and unique dynamic process of [6]CANT* as the first [6]CANT derivative, as well as the synthesis of related linear oligomers, [ n ]ANT* derivatives, as new oligoanthrylenes .…”