New cosolvent-dependent electrochemical sensing behavior of a pair of isostructural ionic nickel(II) coordination polymers

• A pair of novel isostructural Ni(II) CPs 1–2 were constructed. • The composite CP 1 @CNTs was fabricated using one-pot synthesis. • CPs 1 – 2 /GCE show cosolvent-dependent electrochemical sensing to H 2 O 2 and Fe 3+ . • CP 1 @CNTs/GCE shows superior electrochemical sensing to CP 1 /GCE. • CP 1 @CNTs/GCE was used in the practical detection of H 2 O 2 , AA and Fe 3+ . A pair of isostructural ionic nickel(II) chain coordination polymers, {[Ni(bbbm)(H 2 O) 4 ]·ATBIP·2DMF·2H 2 O} n (CP 1) and {[Ni(bbbm)(H 2 O) 4 ]·ATBIP·2DMA·2H 2 O} n (CP 2) with the multi-functional ATBIP 2- anion and flexible bbbm linker was synthesized under ambient condition [H 2 ATBIP = 5-amino-2,4,6-tribromoisophthalic acid, bbbm = 1,4-bis(benzimidazole-1-methyl)benzene]. Furthermore, the composite of CP 1 with carbon nanotubes (CP 1@CNTs) was constructed by adopting “one pot” synthesis strategy. With the help of the hydrogen-bonded chain, CPs 1–2 extend into a 3D supramolecular framework with 1D channels occupied by the cosolvent molecules (DMF/DMA). Remarkably, CPs 1–2/GCE demonstrate cosolvent-dependent electrochemical sensing behavior to H 2 O 2 and Fe 3+ . CP 1/GCE shows more sensitive oxidation sensing to H 2 O 2 than CP 2/GCE in 0.1 M NaOH. Meanwhile, CP 1/GCE demonstrates sensitive reduction sensing to Fe 3+ in 0.1 M H 2 SO 4 , while CP 2/GCE doesn't. Both CPs 1–2/GCE have similar oxidation sensing capabilities to ascorbic acid (AA) in 0.1 M H 2 SO 4 . Moreover, CP 1@CNTs/GCE shows superior electrochemical sensing performance to CP 1/GCE. The LOD of CP 1@CNTs/GCE for sensing of H 2 O 2 , AA and Fe 3+ reaches 0.1 μM, 1.7 μM and 3.4 μM, respectively. Moreover, CP 1@CNTs/GCE was used in the sensitive detection of H 2 O 2 , AA and Fe 3+ in the real-world samples. View of CP 1 @CNTs/GCE showing electrochemical oxidation sensing to H 2 O 2 / AA and reduction sensing to Fe 3+ as well as detection in the actual samples in the corresponding electrolytes.