A water-stable 3D luminescent metal organic framework (MOP), [Eu6Zn(mu 3-OH)(8)(NDC)(6)(H2O)(6)] (1), constructed from heterometallic [(Eu6ZnII)-Zn-III] clusters and electron-rich pi-conjugated 1,4-naphthalenedicarboxylic acid (H2NDC) ligands exhibits highly sensitive, selective, and reversible detection of ronidazole, which represents the first example of luminescent MOFs based on Ln-TM heterometallic clusters for the detection of antibiotics in aqueous solution.