Synthesis of new cholesterol- and sugar-anchored squaraine dyes: further evidence of how electronic factors influence dye formation.
[reaction: see text] Synthesis of new quinaldine-based squaraine dyes linked to cellular recognition elements that exhibit near-infrared absorption (>740 nm) are described. Both product analysis and theoretical calculations substantiate the interesting electronic effects of various substituents in the dye formation reaction. These results are useful in the synthesis of symmetrical and unsymmetrical squaraine dyes that can have potential biological and photodynamic therapeutical applications.