Deoxyribonucleoside-modified squaraines were synthesized by Sonogashira coupling reactions using an unsymmetrical, terminal alkynylated benzothiazolium squaraine dye. These non-natural nucleosides exhibited fluorescent 'turn-on' properties in viscous conditions with an enhancement of >300-fold. The viscosity-dependent fluorescence enhancement was attributed to a combination of hampering both molecular aggregation and intramolecular bond rotation of the squaraine probe. Fluorescence microscopy allowed visualization of highly viscous regions during various stages of cellular mitosis.
All Science Journal Classification (ASJC) codes
- Organic Chemistry
- near-IR imaging
- squaraine dyes
- viscosity sensors