<p>Construction of single probes for simultaneous detection of common trivalent metal ions has attracted much attention due to higher efficiency in analysis and cost. A naphthalimide-based fluorescent probe <b>K1</b> was synthesized for selective detection of Al³⁺, Cr³⁺ and Fe³⁺ ions. Fluorescence emission intensity at 534&#xa0;nm of probe <b>K1</b> in DMSO/H₂O (9:1, v/v) was significantly enhanced upon addition of Al³⁺, Cr³⁺ and Fe³⁺ ions while addition of other metal ions (Li⁺, Na⁺, K⁺, Ag⁺, Cu²⁺, Fe²⁺, Zn²⁺, Co²⁺, Ni²⁺, Mn²⁺, Sr²⁺, Hg²⁺, Ca²⁺, Mg²⁺, Ce³⁺, Bi³⁺ and Au³⁺) did not bring about substantial change in fluorescence emission. The calculated detection limits were 0.32 µM, 0.81 µM, and 0.27 µM for Al³⁺, Cr³⁺, and Fe³⁺, respectively. Probe <b>K1</b> displayed strong anti-interference ability, a large Stokes shift, rapid response, and applicability in a wide pH range for the simultaneous detection of Al³⁺, Cr³⁺ and Fe³⁺ in real water samples. Job’s plot test showed that the stoichiometric ratio of the complexes formed between probe <b>K1</b> and the trivalent metal ions was 1:1. The reversible application of probe <b>K1</b> was realized by addition of Na₂EDTA. A molecular logic gate was built based on the input-output information. This approach may provide a basis for highly selective and sensitive detection of common trivalent cations and for design of memory devices.</p>