title: Synthesis and characterization of new linear pi-conjugated molecules containing bis(ethynylpyridine) units with a benzothiadiazole spacer.
abstract: Three novel 4,7-bis(n-pyridylethynyl)-2,1,3-benzothiadiazoles (n = 2, 3, and 4) were synthesized by using the Sonogashira cross-coupling reaction of 4,7-dibromo-2,1,3-benzothiadiazole with the corresponding ethynylpyridines in the presence of a Pd(II) catalyst. The viologen analogues were also prepared by methylation of pyridyl nitrogen atoms. X-ray structure analysis of these compounds revealed the linear molecular structures with unusual columnar crystal structures. Insertion of a benzothiadiazole moiety into the acetylene-pyridine skeleton brings about a large increase in electron affinity and the bispyridyl compounds obtained here show high fluorescence quantum yields.
authors.affiliation: Department of Electronic Chemistry, Interdisciplinary Graduate School and Engineering, Tokyo Institute of Technology, Nagatsuta, Midori-Ku, Yokohama 226-8502, Japan.
authors.forename: Md
authors.initials: M
authors.lastname: Akhtaruzzaman
authors.forename: Masaaki
authors.initials: M
authors.lastname: Tomura
authors.forename: Md Badruz
authors.initials: MB
authors.lastname: Zaman
authors.forename: Jun-Ichi
authors.initials: J
authors.lastname: Nishida
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Yamashita