Photoresponsive self-assembly and self-organization of hydrogen-bonded supramolecular tapes.
Self-assembling building blocks that are readily functionalizable and capable of achieving programmed hierarchical organization have enabled us to create various functional nanomaterials. We have previously demonstrated that N,N'-disubstituted 4,6-diaminopyrimidin-2(1 H)-one (DAP), a guanine-cytosine hybridized molecule, is a versatile building block for the creation of tapelike supramolecular polymer species in solution. In the current study, DAP was functionalized with azobenzene side chains. 1H NMR, UV/Vis, and dynamic light scattering studies confirmed the presence of nanometer-scale tapelike supramolecular polymers in alkane solvents at micromolar regimes. At higher concentrations (millimolar regimes), the supramolecular polymers hierarchically organized into lamellar superstructures to form organogels, as shown by X-ray diffraction and polarized optical microscopy. Remarkably, the azobenzene side chains are photoisomerizable even in the supramolecular polymers, owing to their loosely packed state supported by the rigid hydrogen-bonded scaffold, enabling us to establish photocontrollable supramolecular polymerization and higher order organization of the tapelike supramolecular polymers into lamellar superstructures.
Department of Applied Chemistry and Biotechnology, Faculty of Engineering, Chiba University, 1-33 Yayoi-cho, Chiba 263-8522, Japan. yagai@faculty.chiba-u.jp
Shiki
S
Yagai
Tomoyuki
T
Iwashima
Keiki
K
Kishikawa
Shoichiro
S
Nakahara
Takashi
T
Karatsu
Akihide
A
Kitamura