| Abstract
| - Three novel 4,7-bis(n-pyridylethynyl)-2,1,3-benzothiadiazoles (n = 2, 3, and 4) were synthesizedby using the Sonogashira cross-coupling reaction of 4,7-dibromo-2,1,3-benzothiadiazole with thecorresponding ethynylpyridines in the presence of a Pd(II) catalyst. The viologen analogues werealso prepared by methylation of pyridyl nitrogen atoms. X-ray structure analysis of these compoundsrevealed the linear molecular structures with unusual columnar crystal structures. Insertion of abenzothiadiazole moiety into the acetylene−pyridine skeleton brings about a large increase inelectron affinity and the bispyridyl compounds obtained here show high fluorescence quantum yields.
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