New N-(pyrenylmethyl) naphtho-azacrown-5 (1) was synthesized as an 'On–Off'fluorescent chemosensor for Cu2+. Excited at 240nm corresponding to the absorption of naphthalene unit (energy donor) of 1, emission at 380nm from pyrene unit (energy acceptor) is observed, indicating that intramolecular fluorescence resonance energy transfer (FRET-On) occurs in 1. When Cu2+ is added to a solution of 1, however, the fluorescence of pyrene is strongly ...
![2,3-bis[2-(2-chloroethoxy)ethoxy]naphthalene Structure](https://image.chemsrc.com/caspic/348/89012-02-2.png)