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 (<bold>CP1</bold>), [Co(L²)(chda)] (<bold>CP2</bold>), [Zn(L¹)(hip)]·DMA·2H₂O (<bold>CP3</bold>), and [Zn(L²)(hip)]·2.8H₂O (<bold>CP4</bold>) [L¹ = <italic>N,N′</italic>-bis(pyridine-3-yl)thiophene-2,5-dicarboxamide, H₂chda = <italic>trans</italic>-1,4-cyclohexanedicarboxylic acid, L² = <italic>N,N′</italic>-bis(pyridine-3-yl)-4,4′-oxybis(benzoic) dicarboxamide, H₂hi<italic>p</italic> = 5-hydroxyisophthalic acid, DMA = <italic>N,N</italic>-dimethylacetamide], have been solvothermally synthesized. X-ray single-crystal diffraction shows that <bold>CP1</bold> is a 2-D 3,5-connected network based on Co-L¹ linear chains and (Co-chda)₂ double chains. <bold>CP2</bold> features a 1-D structure derived from 1-D wave-like (Co-chda)₂ double chains decorated by terminal L² ligands. <bold>CP3</bold> and <bold>CP4</bold> show wave-like (4,4) networks constructed by 1-D Zn-L¹ zigzag and Zn-hip zigzag (for <bold>CP3</bold>)/linear (for <bold>CP4</bold>) chains. The effect of the spacers of S-/O-bridged dipyridylamides on the structures of the title complexes was discussed. Electrochemical behaviors of <bold>CP1</bold>-<bold>CP2</bold> and solid-state luminescent properties of <bold>CP3</bold>-<bold>CP4</bold> were studied. The luminescence investigations show that <bold>CP3</bold> and <bold>CP4</bold> are recycled fluorescent probes for environmentally relevant Fe³⁺ ions. The photocatalytic properties for the degradation of methylene blue (MB) under ultraviolet light irradiation of <bold>CP3</bold>-<bold>CP4</bold> and the recyclable materials after fluorescent sensing Fe³⁺ ions (named <bold>CP3</bold>@Fe³⁺ and <bold>CP4</bold>@Fe³⁺) have also been investigated. [ABSTRACT FROM AUTHOR]