Cobalt 2 perchlorate hexahydrate

Cobalt(II) perchlorate hexahydrate, iron (III) chloride (reagent grade, 97%), red phosphorus (reagent grade, 99.99%), 5 wt% of Nafion, and perchloric acid were purchased from Sigma-Aldrich. Benchmark 20 wt% Ir/C (commercial) and 20 wt% Pt/C (commercial) catalysts were purchased from Johnson Matthey and Premetek, Co. All the chemicals were of analytical grade and were used as received without further purification.

4′-Bromo-2,2′:5′,2″-terpyridine (TCI, Tokyo, Japan), 3,6-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-9-phenylcarbazole (ABCR, Karlsruhe, Germany), 1,1,1,3,3,3-hexafluoropropan-2-ol (Fluorochem, Hadfield, UK), dimethylformamide (DMF), acetone, acetonitrile, hexane, methanol, propan-2-ol, propylene carbonate, tetrabutylammonium hexafluorophosphate (NBu₄PF₆), and cobalt (II) perchlorate hexahydrate (all solvents of analytical grade, Sigma-Aldrich and Merck, Prague, Czech Republic) were used as-received. Tetrakis(triphenylphosphine)palladium(0) (Pd(PPh₃)₄ (Merck, Prague, Czech Republic) was washed three times with methanol (20 mL) and dried before use. Quartz substrates used for optical spectroscopy measurement were purchased from Präzisions Glas & Optik GmbH (Iserlohn, Germany). ITO-coated glass substrates with dimensions of 15 × 20 mm used for thin film preparation for the electrical and electrochemical measurements and the electrode setup required for the electrochemical measurement were purchased from Ossila BV (Leiden, The Netherland). Silicon oxide substrates were used for GIWAX and were purchased from Ossila BV (The Netherland).

Quercetin (Que) (purity ≥ 95%, HPLC), cobalt(II) perchlorate hexahydrate (purity ≥ 98%), 4-morpholinepropanesulfonic acid (MOPS) (purity ≥ 99.5%, titration), dimethyl sulfoxide for spectroscopy (DMSO) (purity ≥ 99.8%), and poly(acrylic acid sodium salt) (PAA) (average Mw ~5100, GPC, purity ≥ 99%) were purchased from Sigma-Aldrich and used without purification. Stock solutions of Que were prepared in pure DMSO and then properly diluted in a buffered aqueous solution (pH 7.4, MOPS 10 mM) to have a final organic solvent content of only 5% v/v. Buffer solutions were prepared by weighing proper amounts of MOPS and titrating with a sodium hydroxide solution to the desired pH. All Que solutions were always freshly prepared and stored in the dark to avoid possible light-induced alterations. The cobalt(II) stock solution was prepared by dissolving the corresponding perchlorate salt in water and titrating the resulting solution with standard EDTA, using orange xylenol as an indicator [60 ]. Poly(acrylic acid) stock solutions were prepared at pH 7.4 in MOPS 10 mM; the concentration of the polymer was expressed per monomer unit of acrylic acid. High-purity water (Millipore, Milli-Q Element A 10 ultrapure water) and A-grade glassware were employed throughout.