SYNTHESIS AND CHARACTERIZATION OF 1,3-BIS-(2-DIALKYLAMINO-5-THIENYL)-SUBSTITUTED SQUARAINES - A NOVEL CLASS OF INTENSIVELY COLORED PANCHROMATIC DYES

By the reaction of N,N-disubstituted 2-aminothiophenes with squaric acid in a 1-butamol-toluene mixture at reflux temperature, a novel heterocyclic type of deeply coloured squaraines is obtained in generally moderate yields. These sparingly soluble dyes exhibit narrow absorption bands at about 700 nm in organic solvents and, in a dispersed form, wide absorption bands ranging into the IR region at about 900 nm.