New Mn(II) coordination polymer constructed from a semi-rigid tricarboxylate acid ligand: Synthesis, structure, and fluorescence recognition of acetylacetone and dichromate anion

We herein report a new manganese(II) coordination polymer (CP), [Mn(HL)(H2O)(2)]center dot(bpe)(0.5) (1), which is incorporated with semi-rigid tricarboxylate 4-(2',3'-dicarboxylphenoxy) benzoic acid (H3L) and 1,2-bis(4-pyridyl) ethylene (bpe) as organic linkers through self-assembly strategy. Single crystal X-ray diffraction indicates that compound 1 contains a one-dimensional (1D) chain structure, which self-assembles into a final three-dimensional (3D) supramolecular framework via the interchain hydrogen bondings. Noticeably, bpe molecules have no practical contribution to the construction of 1D chain structure of 1, which only act as the guest molecules improving the stability of the 3D supramolecular network. More remarkably, the fluorescence signals feature a highly selective and sensitive "turn-off" response toward Cr2O72- and acetylacetone (Hacac) highlighted with the low detection limits of 4.44 mu M and 6.11 ppm, respectively. The linear range for Hacac detecting is 0-5.0 mM, while 0-100 mu M for Cr2O72-. Therefore, the exceptional sensing performance render compound 1 a potential platform for dually probe Hacac and oxo-anion Cr2O72- in wastewater. The crystal structure, selective sensing behavior and probable sensing mechanism of 1 toward both analytes are discussed in detail.