Selenonaphtheno[2,3-d]thiazole derivatives as polymethine dyes

New polymethine dyes — selenonaphtheno2,3-d]thiazole derivatives — were synthesized. It is shown that all of the synthesized dyes which have a selenonaphtheno2,3-d]thiazole residue are more deeply colored than the corresponding 6,7-benzobenzothiazole and thionaphtheno2,3-d] thiazole derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 459–461, April, 1971.