Novel syntheses of naphthoquinone methide near-infrared dyes

Abstract

A novel type of naphthoquinone methide near-i.r. dye has been synthesized by condensing 1-naphthylmalononitrile 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 λ_max. value of 785 nm and reflected 23.3% of the incident light intensity at 830 nm; these properties make the compound a potential diode-laser optical storage medium.