Electron-withdrawing group effects on Coumarin–urea fluorescence

What is it about?

This study investigated the effects of the electron-withdrawing group CF3 substitution position on the fluorescence properties of coumarin–urea derivatives (7CU derivatives) in the absence and presence of an acetate anion (AcO−). Three CF3-7CU derivatives were prepared, with the CF3 group at the ortho, meta, and para positions of the phenyl ring opposite to the coumarin ring, respectively. All three derivatives underwent excited-state intermolecular proton transfer (ESPT) in the presence of AcO−, resulting in dual fluorescence. The emission yield of the tautomer of o-CF3-7CU was an order of magnitude larger than those of m- and p-CF3-7CU, indicating that o-CF3-7CU is a suitable anion sensor. These findings suggest that the inductive effect of the CF3 group is important for the fluorescence properties of 7CU derivatives.

Featured Image

Why is it important?

The study provides valuable insights into the design of new fluorescent probes with excellent visibility. Coumarin–urea derivatives are promising candidates for such probes, and the CF3 substitution position can be used to tune their fluorescence properties.

Perspectives