In situ STM investigation of aromatic poly(azomethine) arrays constructed by "on-site" equilibrium polymerization

Ryota Tanoue, Rintaro Higuchi, Kiryu Ikebe, Shinobu Uemura, Nobuo Kimizuka, Adam Z. Stieg, James K. Gimzewski, Masashi Kunitake

    Research output: Contribution to journalArticlepeer-review

    33 Citations (Scopus)

    Abstract

    Two-dimensional (2D) arrays of π-conjugated aromatic polymers produced by surface-selective Schiff base coupling reactions between an aromatic diamine and an aromatic dialdehyde were investigated in detail using in situ scanning tunneling microscopy. Surface-selective coupling was achieved for almost all diamine/dialdehyde combinations attempted, although several combinations did not proceed even in homogeneous aqueous alkaline solution. Most of the combinations of an aromatic diamine and a dialdehyde, except the combinations of 4,4′-azodianiline with mono/bithiophenedicarboxaldehyde, formed highly ordered π-conjugated polymer arrays on an iodine-modified Au(111) surface in aqueous solution at a suitable pH. The simplest polymer of the various combinations tested, obtained from the combination of 1,4-diaminobenzene with terephthaldicarboxaldehyde, gave a 2D array consisting of linearly connected benzene units. Poly(azomethine) adlayers caused a positive shift in the electrochemical potential of the butterfly shaped oxidative adsorption and reductive desorption of iodine. The acceleration of the reductive desorption of iodine suggests the existence of a weak interaction between the polymer layer and iodine. Not only the first polymer adlayers but also partially adsorbed secondary adlayers with "on-top" epitaxial behavior were frequently observed for all polymer systems. The alignment of the polymer chains in the adlayers possessed a certain regularity in terms of a regular interval between polymer chains because of repulsive interpolymer interactions.

    Original languageEnglish
    Pages (from-to)13844-13851
    Number of pages8
    JournalLangmuir
    Volume28
    Issue number39
    DOIs
    Publication statusPublished - Oct 2 2012

    All Science Journal Classification (ASJC) codes

    • General Materials Science
    • Condensed Matter Physics
    • Surfaces and Interfaces
    • Spectroscopy
    • Electrochemistry

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