Studies on Cyanine Dyes (XXXII)

Abstract

Twenty-three hexamethine (streptovinyl or part of them were composed of isophoron), hemicyanine dyes (A and C), containing benzoxazole nucleus and various amines were synthesized. Two symmetrical heptamethine (straight chain or isophoron), oxacyanine dyes (B and E) and ten pantamethine intermediate dyes (D) containing various amines both ends of them were also synthesize.
There were found the linear relationship between the absorption max. of hemicyanine dyes and bascity of the amine as a composition of them, when the amine's basicity values lie within the range of pKa: 0.99 up to 6.42. And above pKa: 8.32 up to 11.12, there were found abnormality in these hemicyanine dyes.
There exist only a few deviation between the observed absorption max. of (C) dyes and the mean value of the max. of the pair of related symetrical dyes (D) and (E).
These hemicynanine dyes were much effective forsilver iodobromide emulsion and lack of sensitivity at green region of spectrum were characteristic. Sensitization spectra for silver iodobromide emulsion with eight dyes were illustrated.