Squaraine chemistry. Effect of N-pyrrolidino substitution on the synthesis and solid state properties of squaraines

摘要: Abstract Several symmetrical and unsymmetrical squaraines bearing N-pyrrolidino groups have been synthesized by condensation of N-pyrrolidinoaniline derivatives with squaric acid or a 1-aryl-2-hydroxycyclobutene-3,4-dione derivative. As compared to from N,N-dimethylanilines, consistently higher synthetic yield was obtained for the N-pyrrolidino-squaraines in work. The improvement is attributable high nucteophilicity N-pyrrolidinoanilines, owing rigidized ring structure. N-Pyrrolidino substitution shown very little effect on physical spectroscopic properties squaraine. Examinations solid state substituted squaraines, absorption spectroscopy X-ray powder diffraction reveal that group only N-alkyl substituent identified thus far exerts no aggregation squaraine molecules microcrystalline state. This implies should be photoconductive indeed photoconductivities observed xerographic devices incorporating them.