Synthesis of a Near-Infrared Emitting Squaraine Dye in an Undergraduate Organic Laboratory

Document Type

Article

Date of Original Version

7-26-2012

Department

Chemistry

Abstract

Squaraines are a class of organic fluorophores that possess unique photophysical properties, including strong near-infrared absorption and emission. The synthesis of many squaraines involves the condensation of an electron-rich aromatic ring with squaric acid. These reactions are generally refluxed overnight in a benzene–butanol solvent mixture. Reported herein are modifications to the synthesis of a squaraine dye that allowed the experiment to be performed in an undergraduate laboratory setting. The desired compound was formed after a 2-h reflux, using toluene as a co-solvent rather than the more toxic benzene. Moreover, the photophysical properties of the synthesized squaraine compound were analyzed in a separate laboratory period and led to important pedagogical opportunities about the absorption and fluorescence of organic compounds.

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