title: Melamine-barbiturate/cyanurate binary organogels possessing rigid azobenzene-tether moiety.
abstract: Binary organogels were prepared from coaggregates of azobenzene-tethered melamine dimer and cyanurate/barbiturates. In the gels of hydrocarbon liquids, the coaggregates formed heavily entangled nanofibers, morphologies of which are dramatically different from the previously reported coaggregates based on flexible dodecamethylene-tethered melamine dimers. In the present systems, the rigidity of the azobenzene tether may induce regular packing of molecules. In addition, UV-vis and IR spectroscopic measurements provided unequivocal evidence for the contribution of the central amide groups and the azobenzene chromophores in the tether moiety upon forming well-defined nanofibers by hydrogen-bonding and face-to-face (H-type) pi-pi stacking interactions, respectively. As a result of tight molecular packing in the self-assembled nanofibers, the azobenzene moiety in the gel state showed remarkable resistance to trans --> cis isomerization upon irradiation with UV light.
authors.affiliation: Department of Applied Chemistry and Biotechnology, Faculty of Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan. yagai@faculty.chiba-u.jp
authors.forename: Shiki
authors.initials: S
authors.lastname: Yagai
authors.forename: Takashi
authors.initials: T
authors.lastname: Karatsu
authors.forename: Akihide
authors.initials: A
authors.lastname: Kitamura
mesh_terms: D001391:Azo Compounds; D001463:Barbiturates / Q000737:chemistry*; D004583:Electrons; D005782:Gels / Q000737:chemistry*; D006860:Hydrogen Bonding; D007536:Isomerism; D049329:Nanostructures / Q000528:radiation effects; D013057:Spectrum Analysis; D014227:Triazines / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: D001391:Azo Compounds; D001463:Barbiturates; D005782:Gels; D014227:Triazines; C009850:azobenzene; C004632:cyanuric acid; C011907:melamine; C032232:barbituric acid