<p>A highly sensitive multifunctional spectral sensor (RGTM) was synthesized from rhodamine 6G and 2-thiazolemethanamine by one step reaction with the assistance of dry CH₃COONa. In CH₃CN/H₂O (50/50, v/v), Fe³⁺, Al³⁺ and Cr³⁺ enhanced the absorbance of RGTM at 530&#xa0;nm by 44, 11 and 9 folds, and the fluorescence intensity at 553&#xa0;nm by 1159, 624 and 555 folds, respectively, accompanied by significant natural and fluorescent color changes. The absorbance and fluorescence intensity of the solutions increased linearly with the ion concentration in the ranges of 0–45 µM (Fe³⁺), 0–30 µM (Al³⁺), and 0–50 µM (Cr³⁺). The colorimetric detection limits (DLs) for Fe³⁺, Al³⁺ and Cr³⁺ were 2.7, 5.5 and 10.5 µM, and the fluorescent DLs were 1.3, 1.6 and 2.9 nM, respectively. RGTM reversibly chelates Fe³⁺, Al³⁺ or Cr³⁺ in a 1:1 manner with binding constants of 5.64 × 10⁶, 8.63 × 10⁶, and 3.91 × 10⁶ M^− 1, respectively. RGTM can effectively analyze three ions in real water samples, and can also be made into portable solid-supported sensors.</p>