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Self‐Assembly of a Low‐Symmetry Monodendron Containing Two Asymmetrically Linked Molecular Wedges
Author(s) -
Lejnieks Jānis,
Zhu Xiaomin,
Wang Jingbo,
Mourran Ahmed,
Keul Helmut,
Möller Martin,
Anokhin Denis V.,
Ivanov Dimitri A.
Publication year - 2010
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201000567
Subject(s) - mesophase , crystallography , alkyl , columnar phase , materials science , self assembly , orthorhombic crystal system , liquid crystal , scanning tunneling microscope , crystal structure , chemistry , nanotechnology , organic chemistry , optoelectronics
Herein, we describe the synthesis of a low‐symmetry monodendron, 3,4‐bis(dodecyloxy)‐5‐[3,4,5‐tris(dodecyloxy)benzyloxy]benzoic acid, following a simple route which starts from gallic acid ethyl ester and does not require any protecting groups. The self‐assembled structures formed by the compound in 3D and 2D were investigated by synchrotron X‐ray scattering and scanning force microscopy (SFM). In 3D, the compound forms a stable crystalline phase with an orthorhombic lattice in which the alkyl chains connected to different benzene rings form crystalline and amorphous domains. Upon cooling from the isotropic melt the compound exhibits a monotropic smectic mesophase. In 100‐nm‐thick films on a neutral substrate the structure loses its biaxiality, adopting a hexagonal columnar structure with the columns oriented parallel to the substrate. By contrast, in ultrathin films on graphite the SFM likely reveals two crystal orientations, which can develop due to the epitaxial adsorption on the substrate of the alkyl chains pertinent to different benzene rings.