A 3D (3,3,5)-connected Cd(II) MOF as multiresponsive fluorescent sensor of CrO42−, Cr2O72− and dipicolinic acid

• A 3D Cd(II) MOF with unusual trinodal (3,3,5)-connected topology is discribed. • MOF 1 can serve as fluorescent sensor of CrO 4 2− , Cr 2 O 7 2− and dipicolinic acid in aqueous solutions. • MOF 1 also can serve as fluorescent sensor of CrO 4 2− , Cr 2 O 7 2− in river water and dipicolinic acid in serum. Metal-organic frameworks (MOFs) have received great attention in fluorescent sensing application due to their good stability, short response time and maneuverability. Cr(VI) oxo-anions (CrO 4 2− and Cr 2 O 7 2− ) are highly toxic ions for environment water. 2,6-dipicolinic acid (DPA) is the specific biomarker of Bacillus anthracis. Therefore, the exploration of multi-functional fluorescence sensors for detection Cr(VI) oxo-anions and DPA is very necessary. In this work, we synthesized a fluorescent Cd(II) MOF for detection of CrO 4 2− , Cr 2 O 7 2− and DPA in aqueous solution. The Cd(II) MOF formulated as {[Cd 2 (bpda)(bbimh) 0.5 (H 2 O) 4 ]·H 2 O} n ( 1 ) was constructed by 2,3,3′,4′-biphenyltetracarboxylic acid (H 4 bpda) mixed with 1,6-bis(benzimidazole)hexane (bbimh). MOF 1 presents a three-dimensional (3D) framework with unusual trinodal (3,3,5)-connected topology. MOF 1 shows effective sensing ability for detection CrO 4 2− , Cr 2 O 7 2− and DPA via fluorescence quenching effect in aqueous solution with the detection limits being 0.96 μ M, 0.94 μ M and 1.68 μ M, respectively. The quenching mechanisms were elucidated by powder X-ray diffraction (PXRD), UV–vis spectra, lifetimes and theoretical calculations. Furthermore, MOF 1 was also applied to detect CrO 4 2− and Cr 2 O 7 2− in river water sample and DPA in serum sample. This work provides an effective MOF as multifunctional sensor toward water pollutants and biomarker. A new 3D Cd(II) MOF with unusual trinodal (3,3,5)-connected topology is discribed. MOF 1 were explored to be excellet fluorescent sensor of CrO 4 2− , Cr 2 O 7 2− and dipicolinic acid in aqueous solutions.