Advanced Functional Materials
Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Cover Picture: Assembly and Photoinduced Organization of Mono- and Oligopeptide Molecules Containing an Azobenzene Moiety (Adv. Funct. Mater. 9/2007)
An illustration of the phototriggered organization and dispersion of tri-peptide-substituted azobenzene derivatives, as reported on p. 1507 by Yoko Matsuzawa and co-workers. The tri-peptide units form a beta-sheet structure through hydrogen bonding to assemble a fibrous network system. Cis–trans photoisomerization of the azobenzene moiety leads to a large polarity change of the component molecule to break and re-form hydrogen bonds between the tri-peptide units.
Assembled systems consisting of an azobenzene moiety as the photofunctional component and valyl units as the network backbone are investigated. The molecular ordering of these assemblies is examined by spectroscopy and theoretical calculations. The number of valyl units greatly influences the molecular order in the organized systems. Only N-(L-valyl-L-valyl-L-valyl)azobenzene-4-carboxamide (3) forms a complete &bgr;-sheet structure in this artificial assembly. Upon photoirradiation, the azobenzene moieties isomerize completely, revealing the reversibility in the structural organization through the flexibility of the &bgr;-sheet network in this system.