In Situ STM Investigation of Aromatic Poly(azomethine) Arrays Constructed by 鈥淥n-Site鈥?Equilibrium Polymerization

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• 作者：Ryota Tanoue ; Rintaro Higuchi ; Kiryu Ikebe ; Shinobu Uemura ; Nobuo Kimizuka ; Adam Z. Stieg ; James K. Gimzewski ; Masashi Kunitake
• 刊名：Langmuir
• 出版年：2012
• 出版时间：October 2, 2012
• 年：2012
• 卷：28
• 期：39
• 页码：13844-13851
• 全文大小：596K
• 年卷期：v.28,no.39(October 2, 2012)
• ISSN：1520-5827

文摘

Two-dimensional (2D) arrays of 蟺-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鈥?azodianiline with mono/bithiophenedicarboxaldehyde, formed highly ordered 蟺-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 鈥渙n-top鈥?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.