1h benzotriazole

All reagents used in the present study were of analytical grade and all solutions were prepared using ultrapure water obtained from an Elix 3 instrument coupled to a Milli-Q system by Millipore (Bedford, MA, USA).
1-H-benzotriazole of 99% purity (CASn# 95-14-7) was purchased from Sigma-Aldrich (St. Louis, MO, USA), and 5-methyl-1-H-benzotriazole (CASn# 136-85-6, 99%) was purchased from TCI (Zwijndrecht, Belgium) (see Figure 1). Stock solutions of BZT and Me-BZT were prepared by dissolving the solid reagent in purified water and then stored in the fridge at 4 °C and protected from light. Diluted solutions of BZT and Me-BZT were prepared immediately before their use by dissolving a certain amount of stock solution in the electrolyte support.
The buffer solutions used as supporting electrolyte were prepared by adding a diluted solution of sodium hydroxide (Scharlau Chemie S.A., Barcelona) to an appropriate volume of trifluoroacetic acid, purity 99% (Sigma Aldrich, Germany) to adjust pH values (pH = 2.20 when not otherwise indicated) and to achieve a total concentration of trifluoroacetic acid of 0.01 mol L⁻¹.

Commercial organic solvents (toluene ≥ 99.5%, diethyl ether ≥ 99.7%, dichloromethane ≥ 99.8%) were purchased from Sigma Aldrich (Germany) and purified with Na/benzophenone (toluene, diethyl ether) or CaH₂ (dichloromethane) following literature methods [44 ]. 1H-benzotriazole (≥ 99.0%) and potassium borohydride (98%) were Sigma Aldrich (Germany) products, used as received. Yttrium and lanthanide chlorides (99.9% in all the cases) were Strem Chemicals (France) products, used without further purifications. Poly(methyl methacrylate) (PMMA, M_w = 86,000 g mol⁻¹) was purchased from TCI Chemicals (Belgium) and used as received. Potassium tris(benzotryazol-1-yl)borate, K[tbtz], was synthesized accordingly to literature procedures [45 (link)–47 (link)].