Fluorescence Anisotropy Studies on Bodipy (Pyrromethene 546) Dye as a Novel Thermal Probe

In the present work, fluorescence anisotropy studies of BODIPY (pyrromethene 546 or C₁₄H₁₇BF₂N₂) dye have been performed and found that it has a potential to be used as a thermal probe to measure the temperature of microfluid. It is well-known that a dye rotates in its excited state, so to control the molecular rotation of the dye in the excited state, sorbitol is used in the solution. It has been found that adding sorbitol, fluorescence anisotropy increases, fluorescence lifetime decreases. It has been found that adding sorbitol, temperature sensitivity increases. To study the effect of -CH₂ groups on fluorescence properties, another BODIPY (pyrromethene 597 or C₂₂H₃₃BF₂N₂) dye is also used, as C₁₄H₁₇BF₂N₂ and C₂₂H₃₃BF₂N₂ have similar structures with a difference of only -8CH₂ groups. It has been found that C₂₂H₃₃BF₂N₂ has superior properties over C₁₄H₁₇BF₂N₂, i.e., pyrromethene 597 shows larger temperature sensitivity as compared to pyrromethene 546, even without the addition of sorbitol.