title: In situ STM investigation of aromatic poly(azomethine) arrays constructed by "on-site" equilibrium polymerization.
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.
authors.affiliation: Graduate School of Science and Technology, Kumamoto University, Chuo-ku, Kumamoto, Japan.
authors.forename: Ryota
authors.initials: R
authors.lastname: Tanoue
authors.forename: Rintaro
authors.initials: R
authors.lastname: Higuchi
authors.forename: Kiryu
authors.initials: K
authors.lastname: Ikebe
authors.forename: Shinobu
authors.initials: S
authors.lastname: Uemura
authors.forename: Nobuo
authors.initials: N
authors.lastname: Kimizuka
authors.forename: Adam Z
authors.initials: AZ
authors.lastname: Stieg
authors.forename: James K
authors.initials: JK
authors.lastname: Gimzewski
authors.forename: Masashi
authors.initials: M
authors.lastname: Kunitake
mesh_terms: D000327:Adsorption; D000447:Aldehydes / Q000737:chemistry*; D001391:Azo Compounds / Q000737:chemistry*; D003959:Diamines / Q000737:chemistry*; D006046:Gold / Q000737:chemistry; D016252:Microscopy, Scanning Tunneling; D010084:Oxidation-Reduction; D058105:Polymerization; D011108:Polymers / Q000737:chemistry*; D013499:Surface Properties; D013882:Thiosemicarbazones / Q000737:chemistry*
chemical_list: D000447:Aldehydes; D001391:Azo Compounds; D003959:Diamines; D011108:Polymers; D013882:Thiosemicarbazones; C512188:azomethine; D006046:Gold