Photophysical behavior of a novel 4-aza-indole derivative in different solvents: reverse solvatochromism

The photophysical properties of a new 4-aza-indole derivative [ethyl 1-((2-(2-ethoxy-2-oxoethyl)pyridin-3-yl)carbamoyl)-2-hydroxy-1H-pyrrolo-[3,2-b]pyridine-3-carboxylate, 12] were determined in different solvents. Compound 12 exhibited an absorbance peak at 340–360 nm with high fluorescence intensity in the wavelength range from 405 to 417 nm in all solvents except N,N-dimethylformamide (DMF). Compound 12 exhibited reverse solvatochromism behavior depending on the solvent polarity. Furthermore, compound 12 showed very high quantum yield in all solvents independent of their polarity. The results suggest that this novel dye could be used for many applications, e.g., as a labeling agent and in bio- or analytical sensors and/or optoelectronic devices.