Four Novel Cobalt(II) Coordination Polymers Based on Anthracene- Derived Dicarboxylic Acid as Multi-functional Fluorescent Sensors toward Different Inorganic Ions

A series of Co(II)-H2L coordination polymers were prepared with different auxiliary ligands, namely {[Co(L)(bibp)]}n 1, {[Co(L) (bpy)(H2O)]2 center dot 2H2O}n 2, {[Co(L)(bipd)]}n 3, and {[Co(L)(bbibp)]center dot H2O}n 4 (H2L = 5-{(anthracene-9-ylmethyl)-amino}isophthalic acid, bibp = 4,4 '-bis(imidazolyl)biphenyl, bpy = 2,2 '-bipyridine, bipd = 3,5-bis(1-imidazoly)pyridine, and bbibp = 4,4 '-bis(benzoimidazo-1-yl)biphenyl), by a similar solvothermal method. X-ray diffraction analyses revealed that 1, 3, and 4 exhibit a two-dimensional (2D) structure, which further builds the three-dimensional (3D) supramolecular architecture via the weakly interacting hydrogen bonds of C-H center dot center dot center dot O, while 2 displayed a one-dimensional (1D) double-chain architecture extended from two 1D zigzag chains by intermolecular hydrogen bonding interactions. The sensing experiments revealed that 1 and 2 can serve as either individual-and/or multi-responsive sensors to selectively detect Cr3+, Al3+, and Pb2+ ions through the fluorescence turn-on effect, while 3-4 exhibited fluorescence turn-off sensing behavior for Fe3+ ions. Moreover, 1-4 can effectively detect and recognize Cr2O72- and CrO42- due to their high selectivity and sensitivity for fluorescence quenching in aqueous solutions, and the sensing mechanism for various ions has been discussed.

Automated summary

A series of Co(II)-H2L coordination polymers with different auxiliary ligands were synthesized via a solvothermal method. X-ray diffraction analyses showed that compounds 1, 3, and 4 exhibited a two-dimensional structure, while compound 2 displayed a one-dimensional double-chain structure. Compounds 1 and 2 showed fluorescence turn-on sensing for Cr3+, Al3+, and Pb2+ ions, while compounds 3 and 4 exhibited turn-off sensing for Fe3+ ions. Additionally, compounds 1-4 could effectively detect and recognize Cr2O72- and CrO42- ions with high selectivity and sensitivity in aqueous solutions.