A pillar-layer strategy to construct 2D polycatenated coordination polymers for luminescence detection of Cr2O72− and CrO42− in aqueous solution. Issue 33 (25th July 2019) - Long, Bing-Fan
Abstract : Six polycatenated coordination polymers1–6 based on the pillar-layer strategy have been designed and synthesized. Compound6 exhibited strong fluorescence that was selectively quenched by Cr VI ions in aqueous solution at low concentrations. Abstract : Six coordination polymers1–6 were constructed using a rod and loop strategy, in which the H2 L ligand served as the loop and the N-donor ligands (bpp, 1, 4-bimb, 1, 3-bimb, bpb, bpdp and bpeb; bpp = 1, 3-di(pyridin-4-yl)propane; 1, 4-bimb = 1, 4-bis((1 H -imidazol-1-yl)methyl)benzene; 1, 3-bimb = 1, 3-bis((1 H -imidazol-1-yl)methyl)benzene; bpb = 1, 4-di(pyridin-4-yl)benzene; bpdp = 1, 4-bis(4-pyridyl)-2, 3-diaza-1, 3-butadiene; bpeb = 1, 4-bis[2-(4-pyridyl)ethenyl]benzene) acted as the rods. All the complexes except6 possessed binuclear secondary building units (SBUs) and displayed the same topologies. In compounds1–4, two paddle-wheel Zn2 units were linked by two L ligands to form rhombic [Zn4 L2 ] units and these units propagated into a chain-like motif. The N-donor ligands supported the chain-like structure and expanded into 2D layers. Three layers were interpenetrated forming a 2D + 2D → 2D polycatenation backbone. The 2D polycatenation layers were further packed into a 3D structure by hydrogen bonds and unconventional interactions. Compound6 showed a 3D pillar-layer structure consisting of a four-fold interpenetrated network. This coordination polymer had an accessible volume of 38% for the fully desolvated structure and exhibited strong fluorescence that was selectively quenched by Cr VI ions in aqueous solution at low concentrations.