A six-coordinated 3D metal-organic framework (MOF), namely, [Co(BPDC)(3-bpdb)(H 2 O) 2 ] n (1) (H 2 BPDC = 4,4′-biphenyldicarboxylic acid, 3-bpdb = 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene) was purposefully constructed and characterized by single-crystal XRD, IR, elemental analyses, PXRD, SEM, and TGA. Crystal structural analysis revealed that the complex consists of a cds-type three-fold interpenetrated framework.Hirshfeld surface analysis yielded details of the surface characteristics of 1. Signi cant O−H•••O hydrogen bonding interactions, which could promote the stability of the framework, were found is extremely stable in aqueous solution and can resist acids and bases over an extensive pH range of 2 -13. 1 shows brilliant uorescent emission in the solid state and in aqueous solution. Fluorescence titration, cyclic, and antiinterference experiments demonstrated that 1 is an excellent probe for Fe 3+ , CrO 4 2and Cr 2 O 7 2in water.The K sv values of 1 for Fe 3+ , CrO 4 2-, and Cr 2 O 7 2-, which were as high as 1.06 × 10 4 M −1 , 1.50 × 10 4 M −1 , and 1.16 × 10 4 M −1 , respectively, were comparable with those of other sensors. The quenching mechanism of the novel probe was subsequently explained.