Synthetic Approaches to Some Polymethine Asycyanine Colorants; Impact of Functional Additives & Chain Elongation on Visible Electronic Spectra

Twenty one new chromophoric chain β‐substituted polymethine asycyanine (CCBSPA) colorants have been synthesised by catalytic condensation of (i) 4‐dimethylaminophenylbutadientylphenyl ketone; (ii) 4‐dimethylbutadienyl‐4‐nitrophenyl ketone; and (iii) 4‐dimethylaminophenylbutadienyl‐4‐methyl‐phenyl ketone with 2‐methyl quinoline methiodide and 2‐methyl‐6‐substituted quinoline methiodides using piperidine as catalyst & ethanolic DMF as solvent. These colorants were synthesized with the object to study the impact of various functional groups and chain lengthening on visible electronic spectra. All the colorants showed increase in electronic spectra whether electron withdrawing or donating. These colorants also absorb at higher wavelengths when compared to the previously reported butadienylene chain asycyanino‐colorants.