Methine dyes

摘要

Methine dye which contains a cycloheptimidazole nucleus having a substituent at its 1-position thereof and in which the 7-membered ring moiety is substituted by a methine bond having an auxochrome, at the terminal thereof, for forming a conjugated resonance chromophoric group with the 10 pi electron series of the nucleus, showing a long absorption with one or a few methine bonds and have high light-stability and solution-stability.