Synthesis and Properties of Heptamethine Dyes Having Thiopyran Rings

Abstract

Meso-chloroheptamethine dye having thiopyran rings has been synthesized by an efficient procedure. Furthermore the reactive chloro-group at meso-position of the dye was substituted with thiadiazolethioether groups to give several new heptamethine thiopyrylium dyes. These heptamethine thiopyryliuI11 dyes having thiopyran rings have longer .tmax values exceeding l,ul11 in Vis-NIR spectra and 1l11ax of heptamethine thiopyrylium dyes having thiadiazoleth- ioether groups were shifted about 20 nm in the direction of longer wavelength than that of dye having chloro-substituent. These heptamethine thiopyrylium dyes having thiadiazolethioether groups have higher solubilities than that of thiopyrylium dye having chloro-substituent.