Supramolecular Organic Radical Gels Formed with 2,2,6,6-Tetramethylpiperidin-1-oxyl-Substituted Cyclohexanediamines: A Very Efficient Charge-Transporting and -Storable Soft Material

A supramolecular gelator, 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO)-substituted cyclohexanediamine derivative, was synthesized, and its excellent charge-transporting capability was explored. The gels with organic solvents and electrolytes, or with ionic liquids, were formed via reversible sol-gel phase transition at ca. 50 °C. The organogels displayed electrochemical redox responses at E_1/2 = 0.72 V (vs Ag/AgCl) ascribed to the TEMPO moiety. Charge diffusion coefficient of the gel reached 3.3 × 10^-7 cm²/s even in the quasi-solid state, which was comparable to those of the homogeneous solution (ca. 10^-6). The high charge-transporting capability led to the tremendously large current density (a diffusion limited one) of ca. 1.0 mA/cm² on a current collector and long distance for the charge-transporting beyond the organogel thickness of 50 μm. A half-cell of the organogel performed a plateau output voltage at the E_1/2, very high rate, and almost quantitative charging-discharging, and it had cyclability without any additives such as conductive carbons and binder polymers.