In this study a new fluorescent Schiff base; 1,1′-(4,4′-oxybis(4,1-phenylene)bis(azan-1-yl-1-ylidene))bis(methan-1-yl-1-ylidene)dinaphthalen-2-ol (2-HNA) was synthesized and characterized by FT-IR, UV-vis, and ¹H and ¹³C-NMR techniques. Photoluminescent properties of 2-HNA were investigated in different solvents including methanol, THF, DMF, DMSO, acetone, acetonitrile, and dichloromethane. 2-HNA was found to have higher emission intensity and Stoke’s shift value (∆λ_ST) in methanol solution. Relative emission intensity changes (I₀−I/I₀) of 2-HNA in methanol/water mixtures depending on different Cu⁺² ion concentrations were determined and a linearized plot was obtained. Possible interference of some other transition metal ions was also determined. Sensitivity limit of the new sensor was found to be higher than 5 × 10⁻⁷ mol/L. 2-HNA has quite high selectivity against Cu⁺² ion and, thus, can be used as a new fluorescence Cu⁺² ion sensor in practice.