Self-assembled π-conjugated macromolecular architectures — A soft solution process based on Schiff base coupling

Abstract

Two-dimensional supramolecular covalent macromolecular architectures were visualized directly by in-situ scanning tunneling microcopy and colorful -conjugated nanofilms with unique mesostructures formed spontaneously on hydrophobic substrates from aqueous solutions in the presence of simple aromatic building block molecules under ambient conditions. We thus report the results of surface-mediated polycondensation and chemical liquid deposition. The Schiff base coupling reaction applied for this soft solution process is a dynamic reversible covalent coupling reaction that can be managed by careful changes in solution conditions based on 'adsorption' and 'polymerization' equilibria. This low-cost and eco-friendly 'bottom-up' method allows great diversity in terms of the design of primary polymeric chemical structures by the selection of building blocks without the need to consider the solubility of the polymer. This paves the way to a true 'bottom-up' assembly of a vast array of solid-supported, designer supramolecular nanoarchitectures with potential use as functional materials for next-generation organic electronics.

Surface−Enhanced Polymerization via Schiff-Base Coupling at the Solid–Water Interface under pH Control

“…1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 4 Schiff-bases are obtained in a two-step reaction involving complementary functionalities, amino and aldehyde (Scheme 1a). [28][29] This type of surface-confined condensation has been studied in either organic solvents [30][31][32][33][34][35] or aqueous solution: [36][37][38][39][40] in the second case the reactivity is known to be pH-dependent, offering a control on the reaction evolution. At low pH values the majority of the amino groups are in ammonium form (-NH 3 + ) and they are prevented to react with the aldehydes; by increasing the pH, the ammonium ions are deprotonated (to -NH 2 ) and can react forming Schiffbases (i.e.…”

“…One of the proposed polymerization methods at the solid–liquid interface, easy and of low cost, utilizes the formation of Schiff-base functionalities in a condensation polymerization approach. Schiff bases are obtained in a two-step reaction involving complementary functionalities, amino and aldehyde (Scheme a). , This type of surface-confined condensation has been studied in either organic solvents − or aqueous solution: − in the second case the reactivity is known to be pH-dependent, offering a control on the reaction evolution. At low pH values the majority of the amino groups are in ammonium form (−NH 3 + ) and they are prevented to react with the aldehydes; by increase of the pH, the ammonium ions are deprotonated (to −NH 2 ) and can react forming Schiff bases (i.e., imines) through nucleophilic addition at the aldehyde.…”

Gold‐Nanoparticle‐Mediated Assembly of High‐Order DNA Nano‐Architectures

“…Finally, we demonstrate the versatility of the presented SAMPA strategy for the fabrication of 2D nano‐architectures, by further increasing the number of plugs on each module A. Because of relatively weak interactions, [ 14 ] such as van der Waals interactions, hydrogen bonds, [ 15 ] and π stacking, [ 16 ] substrate‐supported self‐assembly is commonly necessary for the fabrication of 2D DNA lattices. Hence, we employed mica‐supported self‐assembly to facilitate the fabrication of 2D nano‐architectures.…”

Lipid-bilayer-assisted two-dimensional self-assembly of DNA origami nanostructures

“…Substrate-supported self-assembly is commonly achieved via relatively weak interactions 28 , such as van der Waals interactions, hydrogen bonds 39 40 41 and π stacking 42 . As an assembly unit for 2D lattices, we first employed a twist-corrected cross-shaped DNA origami with blunt ends ( Fig.…”

“…The alternative approach is surface-diffusion-mediated self-assembly at the liquid–solid interface 25 26 27 . Success in this approach requires a weak adsorption condition that allows molecular mobility on the surface and/or a dynamic adsorption–desorption equilibrium 28 . Rafat et al 26 recently demonstrated a mica-surface-assisted assembly of DNA origami structures by controlling the surface mobility of the origami units via the addition of Na + ions.…”