Shear-Induced Long-Range Uniaxial Assembly of Polyaromatic Monolayers at Molecular Resolution

Abstract

The control of spatial arrangements of molecular building blocks on surfaces opens the foundational step of the bottom-up approach toward future nanotechnologies. Contemporarily, the domain size of monolayers exhibiting crystallinity falls in the submicrometer scale. Developed herein is a method that allows the alignment of polyaromatics with one-single domain for as long as 7 mm. Even more exciting is the fact that the method is applicable to every laboratory and costs practically nothing. The monolayers are prepared simply by placing a piece of folded lens paper against the substrate and the deposition solution containing the compound of interest. The preparation scheme is similar to the Couette flow where the laminar flow takes place between two concentric walls, one of which rotates and creates viscous drag proven useful to align macromolecules. The method can induce an edge-on orientation for 3,6,11,14-tetradodecyloxydibenzo[g,p]chrysene (DBC-OC12), 3,6,12,15-tetrakis(dodecyloxy)tetrabenz[a,c,h,j]anthracene (TBA-OC12), and hexakis(4-dodecyl)-peri-hexabenzocoronene (HBC-C12) and unsubstituted coronene which would otherwise adopt the face-on arrangement on graphite. This finding will be useful to the research and industry that demands high quality alignment of polyaromatics such as OTFTs, optical polarizers, and nanodevices associated with molecular self-assembly.

Oligomeric Tectonics: Supramolecular Assembly of Double‐Stranded Oligobisnorbornene through π–π Stacking

“…To join together 1 anisotropically, a lens paper is placed against an edge of HOPG, and subsequently a 10 mL aliquot of the sample solution is introduced at the center of HOPG. [68] Due to capillary action, the lens paper absorbs the solvent, thereby resulting in a laminar flow that guides the alignment of 1. [68,69] In strong contrast with the dropcast protocol, this procedure produces nearly perfectly patterned nanochannels (Figure 3) with only a few narrow interstices.…”

“…[68] Due to capillary action, the lens paper absorbs the solvent, thereby resulting in a laminar flow that guides the alignment of 1. [68,69] In strong contrast with the dropcast protocol, this procedure produces nearly perfectly patterned nanochannels (Figure 3) with only a few narrow interstices. Representative morphological features of the defects are displayed in the right panels of Figure 3.…”

Coherently Aligned Porphyrin‐Appended Polynorbornenes

“…Tapping-mode atomic force microscopy (TMAFM) images: TMAFM was carried out to morphologically assess the cofacial stacking of the appended porphyrins. To facilitate the imaging, the sample was subjected to shear treatment [16] immediately after it was dropcast on the freshly cleaved surface of highly ordered pyrolytic graphite. A typical image of polymer 2 d, which is a prototype for this series of polynorbornenes, is displayed in Figure 2 and shows a long-range ordered pattern with stripes significantly longer than the apparent length of 2 d. Such an assembly is common for double-stranded polybisnorbornenes [10,11] and is ascribed to intermolecular interactions, such as p-p stacking between terminal groups along the longitudinal dimension and van der Waal interactions between the polymeric backbones and pendant groups in the horizontal direction.…”

The impact of grafted surface defects and their controlled removal on supramolecular self-assembly

“…Common methods to control the quality of crystalline thin films on pristine and ideal surfaces include careful design of the building blocks 10 as well as finding optimal self-assembly conditions by varying the temperature, 11,12 solute concentration, 13 type of solvent, 14,15 solvent flow, 16 and substrate. 17 All of these parameters directly influence the nucleation, growth and/or ripening stages of 2-D crystallization.…”