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Paper | Special issue | Vol 50, No. 2, 1999, pp.895-902
Published online, 1st January, 1970
DOI: 10.3987/COM-98-S(H)88
10-Hydroxy-7-arylindeno[1,2-b]-1,2,5-oxadiazolo[3,4-d]pyridines and 7-Aryl-10-oxoindeno[1,2-b]-1,2,5-oxadiazolo[3,4-d]pyridines— Synthesis, Spectra, and Polymorphism

Shuntaro Mataka,* Hideki Gorohmaru, Thies Thiemann, Tsuyoshi Sawada, Kazufumi Takahashi, and Akiyoshi Tori-i

*Instituete of Advanced Material Study, Kyushu University, 6-1, Kasuga-koen, Kasuga 816-8580, Japan


The novel dyes 7-aryl-10-oxoindeno[1,2-b]-1,2,5-oxadiazolo[3,4-d]pyridines (4) and 7-aryl-10-hydroxyindeno[1,2-b]-1,2,5-oxadiazolo[3,4-d]pyridines (5) have been prepared from acetophenone derivatives. While compounds (4) exhibit a dark red color, they are only weakly fluorescent. Compounds (5) is fluorescent. Of interest is that 10-hydroxy-7-phenylindeno[1,2-b]-1,2,5-oxadiazolo[3,4-d]pyridine(5a)can take four polymorphic forms in the solid state, of which two are yellow (designated as 5a-Y-1 and 5a-Y-2) and two are red (5a-R-1 and 5a-R-2). Two of them are interconvertible (yellow/red) upon exposure to different solvents. X-Ray crystal structure analysis of 5a-R-2 shows the phenyl ring and the indenooxadiazolopyridine ring to be coplanar.