Spacers-directed structural diversity of Co(II)/Zn(II) complexes based on S-/O-bridged dipyridylamides: Electrochemical, fluorescent recognition behavior and photocatalytic properties

To investigate the effect of the spacers of S-/O-bridged dipyridylamides on the structures of Co(II)/Zn(II) complexes, [Co(L1)(chda)]·1.5H2O (CP1), [Co(L2)(chda)] (CP2), [Zn(L1)(hip)]·DMA·2H2O (CP3), and [Zn(L2)(hip)]·2.8H2O (CP4) [L1 = N,N′-bis(pyridine-3-yl)thiophene-2,5-dicarboxamide, H2chda = trans-1,4-cyclohexanedicarboxylic acid, L2 = N,N′-bis(pyridine-3-yl)-4,4′-oxybis(benzoic) dicarboxamide, H2hip = 5-hydroxyisophthalic acid, DMA = N,N-dimethylacetamide], have been solvothermally synthesized. X-ray single-crystal diffraction shows that CP1 is a 2-D 3,5-connected network based on Co-L1 linear chains and (Co-chda)2 double chains. CP2 features a 1-D structure derived from 1-D wave-like (Co-chda)2 double chains decorated by terminal L2 ligands. CP3 and CP4 show wave-like (4,4) networks constructed by 1-D Zn-L1 zigzag and Zn-hip zigzag (for CP3)/linear (for CP4) chains. The effect of the spacers of S-/O-bridged dipyridylamides on the structures of the title complexes was discussed. Electrochemical behaviors of CP1–CP2 and solid-state luminescent properties of CP3–CP4 were studied. The luminescence investigations show that CP3 and CP4 are recycled fluorescent probes for environmentally relevant Fe3+ ions. The photocatalytic properties for the degradation of methylene blue (MB) under ultraviolet light irradiation of CP3–CP4 and the recyclable materials after fluorescent sensing Fe3+ ions (named CP3@Fe3+ and CP4@Fe3+) have also been investigated.