Stimuli‐responsive fluorescent materials are of great interest for sensing applications. Azulene‐based molecular platforms feature a unique combination of optical, luminescence, and stimuli‐responsive properties. In particular, they often display both pH‐ and excitation wavelength‐dependent luminescent properties. Herein, the syntheses of two novel azulene derivatives 4‐(azulen‐2‐yl)‐ N , N ‐dimethylaniline ( 1 ) and 4‐(azulen‐1‐yl)‐ N , N ‐dimethylaniline ( 2 ) is presented via Suzuki–Miyaura cross coupling reactions. Combined experimental and theoretical investigations have been performed to elucidate the complex emissive properties exhibited by 4‐(azulen‐2‐yl)‐ N , N ‐dimethylaniline and 4‐(azulen‐1‐yl)‐ N , N ‐dimethylaniline, as well as those of their protonated forms. An in‐depth understanding of their stimuli‐responsive fluorescent properties is provided which is crucial for the future development of optical sensors.
Gong et al. (Sun,) studied this question.