<p>A fluorescent naphthalene-functionalized metal-organic framework (Al-NDC-MOF) was synthesized using the solvothermal technique and characterized by optical and structural analytical techniques to understand its structure and functional properties. The resulting Al-NDC exhibited intriguing fluorescence, with a significant peak at 430&#xa0;nm when excited at 366&#xa0;nm. In further investigations, it was observed that the fluorescence of Al-NDC could be effectively quenched in the presence of chromium (Cr⁶⁺) and ferric (Fe³⁺) ions in aqueous solutions. This distinctive property of Al-NDC enabled their application as a highly effective probe for Cr⁶⁺ and Fe³⁺ ions. The sensor demonstrated an impressive detection limit of both ions for a working range of 1.5 µM to 195 µM. The discrimination of Cr⁶⁺ and Fe³⁺ ions was achieved by principal component analysis (PCA) and clustering upon acquiring the fluorescence data of all metal ions. The real-world applicability of Al-NDC was evaluated by analysing spiked water samples from tap and lake water. The DFT analysis revealed a significant change in the HOMO-LUMO gap, a finding substantiated by the corresponding UV spectra of Cr⁶⁺ and Fe³⁺ ions with the Al-NDC complex. Consequently, the results gleaned from the study underscore the substantial potential of the AL-NDC-MOF-based fluorescent sensor for impactful applications in environmental monitoring.</p> Graphical abstract <p></p>