Two 4,5-disubstituted-1,8-naphthalimide derivatives 1 and 2 were synthesized as ratiometric fluorescent and colorimetric sensors for Cu 2+ , respectively. In 100% aqueous solutions of 1, the presence of Cu 2+ induces a strong and increasing fluorescent emission centered at 478nm at the expense of the fluorescent emission of 1 centered at 534nm. Compound 2 senses Cu 2+ by means of a colorimetric (primrose yellow to pink) method with a thorough quench in emission attributed to the deprotonation of the secondary amine conjugated to the naphthalimide fluorophore. 1-Cu 2+ and 2-Cu 2+ sense cyanide in ratiometric way via colorimetric and fluorescent changes.