Naphthalimide-based new architecture for fluorescence turn-on sensing of Cu and colorimetric detection of F/CN.

A new molecular structure 1 has been developed on naphthalimide motif. The amine and triazole binding groups have been employed at the 4-position of naphthalimide to explore the sensing behavior of molecule 1. Single crystal x-ray diffraction and other spectroscopic techniques confirm the identity of 1. Compound 1 exhibits high selectivity and sensitivity for Cu ions in CHCN. The binding of Cu shows ∼ 70-fold enhancement in emission at 520 nm. The binding follows 1:1 interaction and the detection limit is determined to be 6.49 × 10 M. The amine-triazole binding site in 1 also corroborates the detection of F through a colour change in CHCN. Initially H-bonding and then deprotonation of amine -NH- in the presence of F are the sequential steps involved in F recognition with a detection limit of 4.13 × 10 M. Compound 1 is also sensible to CN like F ion and they are distinguished by Fe ion. Cu-ensemble of 1 fluorimetrically recognizes F among the tested anions and vice-versa. The collaborative effect of amine and triazole motifs in the binding of both Cu and F/CN has been explained by DFT calculation.