Stimulus-Responsive Azobenzene Supramolecules: Fibers, Gels, and Hollow Spheres

Novel, stimulus-responsive supramolecular structures in the form of fibers, gels, and spheres, derived from an azobenzene-containing benzenetricarboxamide derivative, are described. Self-assembly of tris(4-((E)-phenyldiazenyl)phenyl)benzene-1,3,5-tricarboxamide (Azo-1) in aqueous organic solvent sys...

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Bibliographic Details
Published in:Langmuir 2013-05, Vol.29 (19), p.5869-5877
Main Authors: Lee, Sumi, Oh, Seungwhan, Lee, Joosub, Malpani, Yashwardhan, Jung, Young-Sik, Kang, Baotao, Lee, Jin Yong, Ozasa, Kazunari, Isoshima, Takashi, Lee, Sang Yun, Hara, Masahiko, Hashizume, Daisuke, Kim, Jong-Man
Format: Article
Language:English
Subjects:
Azo Compounds - chemistry
Benzamides - chemistry
Chemistry
Colloidal state and disperse state
Crystallography, X-Ray
Exact sciences and technology
Gels - chemistry
General and physical chemistry
Macromolecular Substances - chemistry
Models, Molecular
Molecular Structure
Particle Size
Porosity
Surface Properties
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Summary:Novel, stimulus-responsive supramolecular structures in the form of fibers, gels, and spheres, derived from an azobenzene-containing benzenetricarboxamide derivative, are described. Self-assembly of tris(4-((E)-phenyldiazenyl)phenyl)benzene-1,3,5-tricarboxamide (Azo-1) in aqueous organic solvent systems results in solvent dependent generation of microfibers (aq DMSO), gels (aq DMF), and hollow spheres (aq THF). The results of a single crystal X-ray diffraction analysis of Azo-1 (crystallized from a mixture of DMSO and H2O) reveal that it possesses supramolecular columnar packing along the b axis. Data obtained from FTIR analysis and density functional theory (DFT) calculation suggest that multiple hydrogen bonding modes exist in the Azo-1 fibers. UV irradiation of the microfibers, formed in aq DMSO, causes complete melting while regeneration of new fibers occurs upon visible light irradiation. In addition to this photoinduced and reversible phase transition, the Azo-1 supramolecules display a reversible, fiber-to-sphere morphological transition upon exposure to pure DMSO or aq THF. The role played by amide hydrogen bonds in the morphological changes occurring in Azo-1 is demonstrated by the behavior of the analogous, ester-containing tris(4-((E)-phenyldiazenyl)phenyl)benzene-1,3,5-tricarboxylate (Azo-2) and by the hydrogen abstraction in the presence of fluoride anions.
ISSN:0743-7463
1520-5827
DOI:10.1021/la400159m