engleski

New stable, isolable triarylmethyl based dyes absorbing in the near infrared

A series of new intensely coloured multicharged methylium compounds containing the 4-[2-ferrocenylethenyl]phenyl group and with significant electronic absorption in the near infrared have been prepared via acidification of the tertiary carbinols obtained by reaction of 4-[FcCHCH]C6H4Li with diethyl isophthalate, diethyl terephthalate, diethyl phthalate or the triethyl ester of 1, 3, 5-benzene carboxylic acid. Even more stable dyes were prepared from two new triarylmethanol derivatives containing 2, 6-dimethoxy-4-[2-(ferrocenyl)ethenyl]phenyl or 2, 6-dimethoxy-4-[2-[4-(dimethylamino)phenyl]ethenyl]phenyl groups which were prepared by reaction of 4-[FcCHCH]-2, 6-MeO2C6H2Li or 4-[4-Me2NC6H4CHCH]-2, 6-MeO2C6H2Li (Fc = ferrocenyl) with diethyl carbonate. These carbinols on treatment with acid deposit dark-purple crystals which have been isolated and characterised spectroscopically. They absorb in the near infrared and, whereas their solutions begin to decolourise only after several days, they display long-term stability to air and moisture in the solid state.

near infrared; carbenium ion; ferrocenyl; stilbene

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