The synthesis of novel asymmetrical benzoins and bis(dithiobenzil) metal complex dyes containing ethoxyethoxy groups and their absorption characteristics

Asymmetrical bis(dithiobenzil) metal complex (BMC), as a NIR(Near Infra-Red) absorbing dye, was synthesized via preparation of asymmetric benzoin intermediates. Four synthesized dyes were characterized by elemental analyses and GC-Mass, ¹H-NMR(nuclear magnetic resonance) analysis. The absorption characteristics of the synthesized dyes in the NIR region were measured using UV-VIS spectrophotometer. Maximum absorbing wavelength was shifted depending on the character and position of substituents in the bis(dithobenzil) metal complex.