title: Periodic Functionalization of Surface-Confined Pores in a Two-Dimensional Porous Network Using a Tailored Molecular Building Block.
abstract: We present here the periodic functionalization of a two-dimensional (2D) porous molecular network using a tailored molecular building block. For this purpose, a dehydrobenzo[12]annulene (DBA) derivative, 1-isoDBA, having an isophthalic acid unit connected by an azobenzene linker to a C12 alkyl chain and five C14 chains, was designed and synthesized. After the optimization of monolayer preparation conditions at the 1,2,4-trichlorobezene (TCB)/graphite interface, scanning tunneling microscopy (STM) observation of the self-assembled monolayer of 1-isoDBA revealed the formation of extended domains of a porous honeycomb-type molecular network, which consists of periodically located nanowells each functionalized by a cyclic hexamer of hydrogen-bonded isophthalic acid units and those without functional groups. This result demonstrates that the present strategy based on precise molecular design is a viable route to site-specific functionalization of surface-confined nanowells. The nanowells of different size can be used for guest coadsorption of different guests, coronene COR and hexakis[4-(phenylethynyl)phenylethynyl]benzene HPEPEB, whose size and shape match the respective nanowells. STM observation of a ternary mixture (1-isoDBA/COR/HPEPEB) at the TCB/graphite interface revealed the site-selective immobilization of the two different guest molecules at the respective nanowells, producing a highly ordered three-component 2D structure.
authors.affiliation: Division of Frontier Materials Science, Graduate School of Engineering Science, Osaka University , Toyonaka, Osaka 560-8531, Japan.|PRESTO, Japan Science and Technology Agency (JST) , Toyonaka, Osaka 560-8531, Japan.
authors.forename: Kazukuni
authors.initials: K
authors.lastname: Tahara
authors.affiliation: Division of Frontier Materials Science, Graduate School of Engineering Science, Osaka University , Toyonaka, Osaka 560-8531, Japan.
authors.forename: Kenta
authors.initials: K
authors.lastname: Nakatani
authors.affiliation: Division of Frontier Materials Science, Graduate School of Engineering Science, Osaka University , Toyonaka, Osaka 560-8531, Japan.
authors.forename: Kohei
authors.initials: K
authors.lastname: Iritani
authors.affiliation: Division of Molecular Imaging and Photonics, Department of Chemistry, KU Leuven , Celestijnenlaan 200 F, 3001 Leuven, Belgium.
authors.forename: Steven
authors.initials: S
authors.lastname: De Feyter
authors.affiliation: Division of Frontier Materials Science, Graduate School of Engineering Science, Osaka University , Toyonaka, Osaka 560-8531, Japan.
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Tobe
keywords: dehydrobenzo[12]annulene; functionalized nanowells; porous molecular network; scanning tunneling microscopy; self-assembly; solid−liquid interface