One-step construction of the amino-substituted squaraine dye backbone was discovered unexpectedly in an amidation reaction. Under the catalysis of Mukaiyama's reagent, (4-dimethylamino)phenylacetic acid and bulky secondary amine 2,2,6,6-tetramethylpiperidine give the reduced form of aminosquaraine instead of amide as the major product. The reduced form of aminosquaraine can be oxidized to a dark-colored conjugated aminosquaraine within seconds. The method provides a novel and facile way to functionalize the four-membered core of squaraine dye.

Original languageEnglish (US)
Pages (from-to)264-267
Number of pages4
JournalDyes and Pigments
StatePublished - Aug 1 2016


  • Amidation
  • Aminosquaraine
  • Dye functionalization
  • One-step
  • Oxidation
  • Squaraine

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Process Chemistry and Technology


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