A water-stable luminescent Co(II) coordination polymer as probe for efficient detection of Cr(VI)-anions (Cr2O72– and CrO42–) in aqueous solution

A new 2D Co(II)-based coordination polymer (CP), {[Co(TCPA)(L)]·H2O}n (1) (L = 1,3-bis(5,6-dimethylbenzimidazol-1-yl)propane, and H2TCPA = 2,3,5,6-tetrachloroterephthalic acid), was successfully constructed under hydrothermal condition. 1 features a 2D (4,4)-connected layered structure. Adjacent sheets of 1 are interconnected via π···π stacking interactions generating a 3D supramolecular framework. Further, 1 exhibits the high sensing ability for Cr2O72– (pH = 4.0) and CrO42– (pH = 11.0) in aqueous systems through luminescence quenching effects. The Ksv values are 1.43 × 104 M−1, and 1.24 × 104 M−1 for Cr2O72–, and CrO42–, respectively. Besides, the possible selective fluorescence sensing mechanism was speculated.