Abstract
Two kinds of new squarylium dyes have been prepared. Aminosquarylium dyes (ASQ) (6) have been prepared by condensation of aminosquarates (3) and 1-ethyl-2, 3, 3-trimethylindolenium iodide (5). New aminosquarylium dye 6a absorbed at a longer wavelength (18nm) than the corresponding squarylium dye (SQ) 7c.
A new class of dithiosquarylium dyes (DTSQ 8) has also been synthesized by the reaction of squarylium dye (SQ) with Lawesson's reagent or P4S10. The λmax of DTSQ dyes undergoes a bathochromic shift of about 25nm compared with corresponding SQ dyes.
The visible absorption spectra of ASQ and DTSQ dyes are well accounted for by PPP-MO calculations.
