A Metal–Organic Framework Based on a Nickel Bis(dithiolene) Connector: Synthesis, Crystal Structure, and Application as an Electrochemical Glucose Sensor

Functionalizing the redox-active tetrathiafulvalene (TTF) core with groups capable of coordination to metals provides new perspectives on the modulation of architectures and electronic properties of organic-inorganic hybrid materials. With a view to extending this concept, we have now synthesized nickel bis(dithiolene-dibenzoic acid), [Ni(C₂S₂(C₆H₄COOH)₂)₂], which can be considered as the inorganic analogue of the organic tetrathiafulvalene-tetrabenzoic acid (H₄TTFTB). Likewise, [Ni(C₂S₂(C₆H₄COOH)₂)₂] is a redox-active linker for new functional metal-organic frameworks, as demonstrated here with the synthesis of [Mn₂{Ni(C₂S₂(C₆H₄COO)₂)₂}(H₂O)₂]·2DMF, (1, DMF = N,N-dimethylformamide). 1 is isomorphic to the reported [Mn₂(TTFTB)(H₂O)₂] (2) but is a better electrochemical glucose sensor due to the multiple oxidation-reduction states of the [NiS₄] core, which allow glucose to be oxidized to glucolactone by the high oxidation state [NiS₄] center. As a non-enzymatic glucose sensor, 1 on Cu foam (CF), 1-CF, was synthesized by a one-step hydrothermal method and exhibited an excellent electrochemical performance. The fabricated 1-CF electrode offers a high sensitivity of 27.9 A M^-1 cm^-2, with a wide linear detection range from 2.0 × 10^-6 to 2.0 × 10^-3 M, a low detection limit of 1.0 × 10^-7 M (signal/noise = 3), and satisfactory stability and reproducibility.