Free-Standing Mono layer Two-Dimensional Supramolecular Organic Framework with Good Internal Order

Utilizing dynamic self-assembly and self-sorting to obtain large-area, molecularly precise monolayered structures represents a promising approach toward two-dimensional supramolecular organic frameworks (2D SOF) or 2D supramolecular polymers. So far, related approaches suffer from small domain sizes, fragility and weak long-range internal order. Here we report on the self-assembly of a host-guest enhanced donor-acceptor interaction, consisting of a tris(methoxynaphthyl)-substituted truxene spacer, and a naphthalene diimide substituted with N-methyl viologenyl moieties as donor and acceptor monomers, respectively, in combination with cucurbit[8]uril as host monomer toward monolayers of an un…

Thermotropic properties and molecular packing of discotic tristriazolotriazines with rigid substituents.

Tristriazolotriazines with a threefold dialkoxyaryl substitution have been prepared by Huisgen reaction of cyanuric chloride and the corresponding tetrazoles. Although these dyes show a negative or inverted solvatochromism of the UV/Vis absorption, their fluorescence is strongly positive solvatochromic. These discotic fluorophores are also emissive in their solid state and in their broad liquid-crystalline mesophase. The structural study indicates that the thermotropic properties and organization of these systems can be well tuned by the steric demand of the aryl groups. Depending on the substituents, the compounds showed either a pure crystalline phase or a highly complex helical superstru…

Cover Picture: Nanostructuring with a Crosslinkable Discotic Material (Small 8/2007)

Uniaxial Alignment of Polycyclic Aromatic Hydrocarbons by Solution Processing

The self-organization of two polycyclic aromatic hydrocarbons with different aromatic core sizes, dodecylphenyl-substituted hexa-peri- hexabenzocoronene and an extended disk consisting of 96 carbon atoms 6-fold-alkyl-substituted, on the surface from solution has been investigated. Highly ordered surface layers of both materials could be obtained by the zone-casting technique, despite an apparently low self-organization in drop-cast films. The zone-cast films revealed high macroscopic uniaxial orientation of the columns with a molecular edge-on arrangement on the glass support as confirmed by polarized optical microscopy, UV-vis measurements in polarized light, high-resolution transmission e…

Positional Isomers of Chromophore–Peptide Conjugates Self-Assemble into Different Morphologies

Ordering π-systems into defined supramolecular structures is important for the development of organic functional materials. In recent years, peptides with defined secondary structures and/or self-assembly properties were introduced as powerful tools to order peptide-chromophore conjugates into different morphologies. This work explores whether or not the directionality of peptides can be used to control the self-assembly. The position of the π-system in conjugates between oligoprolines and perylene monoimide (PMI) chromophores was varied by attaching the PMI moiety to the second-to-last residue from the C- and N-termini, respectively. Microscopic and diffraction analysis revealed that the p…

Synthesis and helical supramolecular organization of discotic liquid crystalline dibenzo[hi,st]ovalene

Dibenzo[hi,st]ovalene (DBOV) has emerged as a new polycyclic aromatic hydrocarbon (PAH) with intriguing optical properties with strong red emission. Nevertheless, DBOV derivatives thus far synthesized either had mesityl groups that hinder the pi-pi stacking of the aromatic cores or showed low solubility, and the self-assembly of DBOVs has not been investigated. In this work, two 3,4,5-tris(dodecyloxy)phenyl (TDOP) groups are introduced at the meso-positions of DBOV in order to enhance its solubility without compromising the intermolecular interactions. The obtained DBOV-TDOP forms at elevated temperatures a discotic liquid crystalline phase. Due to pi-pi-stacking interactions as well as loc…

A Zone-Casting Technique for Device Fabrication of Field-Effect Transistors Based on Discotic Hexa-peri-hexabenzocoronene

Solution-processed transparent ferroelectric nylon thin films

We have developed a method to solution process strongly hydrogen-bonded odd nylons into ferroelectric thin films.

Self-assembly of amphiphilic imidazolium-based hexa-peri-hexabenzo-coronenes into fibreous aggregates

Imidazolium-based amphiphilic hexa-peri-hexabenzocoronenes were synthesized and shown to undergo ordered columnar self-assembly in solid-state as well as in solution to yield defined nanofibers upon solution drop casting onto solid substrate.

Layered Thiadiazoloquinoxaline-Containing Long Pyrene-Fused N-Heteroacenes

Three thiadiazoloquinoxaline-containing long pyrene-fused N-heteroacenes with 8, 13, and 18 rings were designed and synthesized. They show high electron affinities (EAs) of approximately 4.1 eV, which were derived from the onset of the reduction peaks in cyclic voltammetry. Crystal structure analysis revealed in-plane extension through close contacts between thiadiazole units as well as layered packing, enabling in-plane and interlayer electron transport. Organic field-effect transistor devices provided electron mobilities, which suggest a potential way to enhance the charge transport in long N-heteroacenes.

Tetrakis(oxadiazolylphenyl)pyrazines: New St. Andrew's Cross-Shaped Liquid Crystals.

π-Conjugated molecules with the shape of St. Andrew's cross have been synthesized via fourfold Huisgen reaction. Four 2,5-diaryl-1,3,4-oxadiazol arms are attached to a central pyrazine nucleus. These fluorescent stars, when decorated with a rim of eight alkoxy side chains are discotic liquid crystals. Depending on the substitution pattern, the width of the liquid phase varies within a broad range of 25 °C to 250 °C. In their liquid crystalline phase, the molecules assemble in a typical hexagonal columnar supramolecular arrangement.

Liquid Crystalline Ordering and Charge Transport in Semiconducting Materials

Organic semiconducting materials offer the advantage of solution processability into flexible films. In most cases, their drawback is based on their low charge carrier mobility, which is directly related to the packing of the molecules both on local (amorphous versus crystalline) and on macroscopic (grain boundaries) length scales. Liquid crystalline ordering offers the possibility of circumventing this problem. An advanced concept comprises: i) the application of materials with different liquid crystalline phases, ii) the orientation of a low viscosity high temperature phase, and, iii) the transfer of the macroscopic orientation during cooling to a highly ordered (at best, crystalline-like…

Melt processing of hexa-peri-hexabenzocoronene on the water surface

A discotic polycyclic aromatic hydrocarbon, hexa-peri-hexabenzocoronene, was oriented by slow cooling from the isotropic phase on a water surface as a film. For melt processing at low temperatures, an HBC derivative with long swallow-tailed alkyl side chains was chosen. The supramolecular organization in the resulting thin layer was investigated by electron microscopy. In high-resolution mode, the structural study showed large domains in which the columnar structures were oriented uniaxially with an edge-on arrangement of the hydrophobic molecules. The length of the stacks exceeded several hundred nanometers without obvious defects. The small-area analysis by TEM allowed the direct visualiz…

Nanostructuring with a crosslinkable discotic material.

A high-yielding synthesis afforded a hexa-peri-hexabenzocoronene carrying acrylate units at the end of six attached alkyl spacers. The polymerization of these acrylate moieties could be initiated with thermal energy and through direct photoactivation without the addition of a photoinitiator. This allowed the organization of the liquid-crystalline material to be fixed in either the crystalline state or the mesophase, which preserved the organization in the respective phase. The use of a focused synchrotron beam permitted selected regions of a thin film to be rendered insoluble. After "developing" the film in this lithographic process by dissolving the soluble, unpolymerized material, defined…

Dicyanobenzothiadiazole Derivatives Possessing Switchable Dielectric Permittivities

Benzothiadiazoles are important electron acceptors and are frequently employed as electron-deficient components of donor-acceptor polymers. We report the effect of nitrile functionalities on the reactivity, steric hindrance, optoelectronic properties, and dielectric permittivity in dicyanobenzothioadiazole (DCNBT). Dielectric spectroscopy in the bulk and in solution assisted by DFT-calculations revealed that these molecules can be engineered to engender maximum values of the dipole moment and of dielectric permittivity due to the strong electron-withdrawing effect of the nitrile groups. The self-assembly in the bulk was investigated by X-ray scattering performed on single crystals, fibers (…

CCDC 1533973: Experimental Crystal Structure Determination

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CCDC 1826069: Experimental Crystal Structure Determination

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CCDC 1816642: Experimental Crystal Structure Determination

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CCDC 1533972: Experimental Crystal Structure Determination

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CCDC 1533971: Experimental Crystal Structure Determination

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CCDC 1533733: Experimental Crystal Structure Determination

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CCDC 1533970: Experimental Crystal Structure Determination

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CCDC 1816643: Experimental Crystal Structure Determination

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CCDC 1533734: Experimental Crystal Structure Determination

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