Fluorophores, fluorescent polymers, and energy transfer in an undergraduate laboratory setting

Organic fluorophores are rarely synthesized at the undergraduate level, often because of the tedious procedures required for their synthesis. One example of such fluorophores, squaraines, are a class of near-infrared emitting fluorophores with unique photophysical properties. Squaraines are often synthesized via the condensation of an electron-rich aniline with squaric acid, refluxed overnight in a mixed solvent system. Reported herein are the syntheses of a variety of organic fluorophores in an undergraduate laboratory setting, including modifications to the literature-reported synthesis of a particular squaraine molecule that allowed it to be synthesized at the undergraduate level. The photophysical properties of these fluorophores can also be analyzed. Finally, the fluorophores can be used for a variety of interesting applications, including the fabrication of hybrid thin films and nanoparticles with fluorescent conjugated polymers.