title: Elongation of the pi-system of phthalocyanines by introduction of thienyl substituents at the peripheral beta positions. Synthesis and characterization.
abstract: 1,4,8,11,15,18,22,25-octabutoxyphthalocyanines ((OBu)8Pcs) having eight 2-thienyl (1) and [2,2'-bithiophene]-5-yl (2) groups at beta positions and their zinc(II) and cobalt(II) derivatives were prepared from 2-thienyl- (3) or [2,2'-bithiophene]-5-yl (4)-substituted phthalonitriles in moderate to good yields. The electronic absorption spectra of the Pcs showed red-shifted Q-bands relative to beta-unsubstituted (OBu)8Pcs. The longer substituent, the [2,2'-bithiophene]-5-yl group, is more effective than the 2-thienyl group in enlarging the pi-conjugated system of the Pcs. The ring oxidation potential obtained by cyclic voltammetry shifted cathodically with increasing chain length, indicating destabilization of the HOMOs. Due to the shift of the Q-band, 2-thienyl- and [2,2'-bithiophene]-5-yl-substituted Pcs exhibit a remarkable color change from the original green color.
authors.affiliation: Department of Functional Polymer Science, Faculty of Textile Science and Technology, Shinshu University, Tokida 3-15-1, Ueda 385-8567, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Muto
authors.forename: T
authors.initials: T
authors.lastname: Temma
authors.forename: M
authors.initials: M
authors.lastname: Kimura
authors.forename: K
authors.initials: K
authors.lastname: Hanabusa
authors.forename: H
authors.initials: H
authors.lastname: Shirai