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

Abstract

Self-assembly at the molecular level in solutions or on a surface is a subject of current interest. Herein we describe the tailoring of oligobisnorbornene 1, which represents an innovative concept of a preorganized building block on the tens of nanometer scale. The rodlike 1 has vinyl and styrenyl end groups. Scanning tunneling microscopy (STM) reveals that the oligomers aggregate anisotropically along the long axis and form a one-dimensional assembly in which, remarkably, no interstitial gap appears between neighboring oligomers. Dynamic light-scattering (DLS) measurements indicate that the assembly develops in solution. With a shear treatment for dropcast films, a unidirectionally ordered domain with a defect density less than 0.5 % can be prepared. Simulation results by molecular dynamics suggest that there may be multiple interactions such as pi-pi stacking and dipolar attractions taking place between the termini of the oligomers. To demonstrate the importance of double bonds in the oligomeric backbones and termini towards the tectonic assembly, a hydrogenated analogue was synthesized; pi-pi interactions are thus less significant and the film morphology is completely different from that of 1. This work extends the concept of molecular tectonics to preorganized oligomers and opens up a new avenue of nanopatterning toward nanodevices.

Cis, Isotactic Selective ROMP of Norbornenes Fused with N-Arylpyrrolidines. Double Stranded Polynorbornene-Based Ladderphanes with Z-Double Bonds

“…These results suggest that there is a symmetry plane between adjacent monomeric units in 16a and the double bonds should therefore be in cis configuration. This pattern is completely different from those of 10a having trans double bonds and isotactic structure, which exhibits essentially two sets of 13 C signals in the high field region because of the lack of the symmetric plane between adjacent monomeric units. 9 The same hydrogenated product 17 obtained from the diimide reductions of 16a and of 10a indicates that both 16 and 10 should have same isotactic stereochemistry.…”

“…11,13 Stacking interaction between styrene and vinyl end groups along the longitudinal axis of the polymer and van der Waals interaction between polymeric backbones in the second dimension may be responsible for such ordered pattern. 13 Polymers 19 and 21 have similar end groups (styrene and substituted vinyl). It is therefore envisaged that a similar aggregate may also be formed from these ladderphanes with all cis double bonds.…”

“…After being subjected to STM scanning, the former becomes disordered after a couple of imaging frames while the latter is unaffected. 11,13 The observation suggests weaker interactions of the cis polymer 19 with the substrate and between the terminal groups. 19-containing phenyloctane on HOPG and subsequently being shear-aligned by removal excess solvent with a piece of tissue.…”

Oligonorbornenes with Hammock‐Like Crown Ether Pendants as Artificial Transmembrane Ion Channel

“…It is noteworthy that polynorbornenes, whether single‐ or double‐stranded, can easily form aggregates in organic solvents 10. 15 Such aggregation might also take place in the hydrophobic environment of a liposome.…”

Solvent‐Dependent Self‐Assembly of 4,7‐Dibromo‐5,6‐bis(octyloxy)benzo[c][1,2,5] Thiadiazole on Graphite Surface by Scanning Tunneling Microscopy

“…Self-assembly has been considered as an elegant "bottomup" approach for fabricating nanostructured materials [1][2][3][4]. Due to the convenient and straightforward experimental methods, scanning tunneling microscopy (STM) is widely used to be an effective tool for studying assembly nanostructures in ambient conditions [5,6].…”