title: Pyridylazulenes: synthesis, color changes, and structure of the colored product.
abstract: A facile method for the synthesis of 1- and 2-pyridylazulenes, and of 1,3-dipyridylazulenes, is described. Color and spectral changes of these pyridylazulenes upon the addition of either acid or metal ions were investigated in detail. The color changed from blue to red upon the addition of trifluoroacetic acid or soft metal ions, depending on the substitution patterns of the pyridyl group on the azulene skeleton. The structures of the protonated or coordinated products were examined on the basis of the spectral data. It was found that the protonation or coordination of metal ions occurred on the nitrogen atom of the pyridine ring, but not on the carbon atom of azulene ring. The transition intervals of several pyridylazulenes for use as pH indicators were also determined.
authors.affiliation: Department of Clinical Nutrition, Faculty of Health Science, Suzuka University of Medical Science, Suzuka, Mie 510-0293, Japan. s-waka@suzuka-u.ac.jp
authors.forename: Shigeharu
authors.initials: S
authors.lastname: Wakabayashi
authors.forename: Yuri
authors.initials: Y
authors.lastname: Kato
authors.forename: Keiko
authors.initials: K
authors.lastname: Mochizuki
authors.forename: Rieko
authors.initials: R
authors.lastname: Suzuki
authors.forename: Mana
authors.initials: M
authors.lastname: Matsumoto
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Sugihara
authors.forename: Makoto
authors.initials: M
authors.lastname: Shimizu
mesh_terms: D052176:Azulenes / Q000138:chemical synthesis*; D001400:Azurin / Q000737:chemistry*; D002413:Cations, Divalent; D003116:Color; D006863:Hydrogen-Ion Concentration; D019216:Metals, Heavy / Q000737:chemistry; D015394:Molecular Structure; D011725:Pyridines / Q000138:chemical synthesis* / Q000737:chemistry*; D013057:Spectrum Analysis; D014269:Trifluoroacetic Acid / Q000737:chemistry
chemical_list: C518680:1,3-dipyridylazulene; C518681:1-pyridylazulene; C518682:2-pyridylazulene; D052176:Azulenes; D002413:Cations, Divalent; D019216:Metals, Heavy; D011725:Pyridines; D001400:Azurin; D014269:Trifluoroacetic Acid; C023666:pyridine