a,b, Rotating disc electrode linear sweep voltammogram for the materials 1a[Cs]–3a[Cs] and 1b[Cs]–3b[Cs], respectively. The experiment was conducted in a single cell at pH 7.1 in 50 mM KPi buffer, 1 M KNO3. Rotating disc speed, 2,000 r.p.m. Scan rate, 2 mV s−1. c,d, Bulk electrolysis of compounds 3a[Cs] (c) and 3b[Cs] (d) performed at pH = 7.1 in 50 mM KPi buffer, 1 M KNO3 at 1.4 V versus Ag/AgCl.