Novel Syntheses of Naphthoquinone Methide Near-infrared Dyes
A novel type of naphthoquinone methide near-i.r. dye has been synthesized by condensing 1-naphtyl-malononitrile or 1-naphthylcyanoacetamide with p-N,N-dialkylaminoanilines in the presence of an oxidizing agent under alkali conditions.These dyes can absorb near-i.r. light at 722-761 nm.A dye film of 4-(4-diethylamino-2-methylphenylimino)-1,4-dihydronaphthylidenemalononitrile showed a λmax. value of 785 nm and reflected 23.3percent of the incident light intensity at 830 nm; these properties make the compound a potential diode-laser optical storage medium.