Sncl4

The NMR spectra were acquired utilizing a Varian Gemini 2000 instrument (1H 300 MHz, 13C 75.45 MHz) or a Bruker Avance 300 (1H 300 MHz, 13C 75.45 MHz) spectrometer. Chemical shifts (δ) in ppm are given relative to Me4Si coupling constants (J) in Hz. EI mass spectra were recorded with a Micromass GC-T. Melting points were recorded with an electrothermal melting point apparatus and were uncorrected. Analytical TLC was carried out on Merck 5785 Kieselgel 60F254 fluorescent plates. Flash chromatography uses silica gel of 35–70 µm particle size. Dimethylformamide was distilled from magnesium sulfate. Phosphorus pentoxide, SnCl4, and 2-Fluoro-4-nitrobenzoic acid were purchased from Sigma-Aldrich (Darmstadt, Germany). Dichloromethane, diethyl ether, and hexane-ethyl acetate were procured from Sigma-Aldrich (Darmstadt, Germany).

The electrode with nominal composition Ti/RuO₂-TiO₂-SnO₂ (Ru:Ti:Sn 50:40:10 atom. %) were prepared through thermal decomposition (T_calcination: 450 °C). The polymeric film subjected to high temperatures for the organic material is eliminated to obtain the oxide coating. Precursor solutions were prepared at the presence of 0.1 mol of RuCl₃, C₁₂H₂₈O₄Ti, and SnCl₄ (all Sigma-Aldrich, St. Louis, MO, USA), in ethanol. After, the precursor mixtures were dissolved at the presence of the 4.0 mol acid citric and 16.0 mol ethylene glycol (all Sigma-Aldrich) and heated at T = 90 °C to occurred esterification process. Before the deposition of oxide films, the plate of titanium (2.0 cm²) used as a substrate was sandblasted (105–210 µm) in order to improve the adherence of metal oxides. After that, the surface was degreased and submitted to chemical activation in concentrated HCl (20% v/v) for 30 min, washed in a solution of oxalic acid (10%) for 20 min, and rinsed with ultrapure water. Afterwards, the electrode was dried at low temperature. The precursor mixtures were deposited on the pretreated Ti substrate. The deposited coatings were thermally treated in the oven at 130 °C for 10 min, then again at 450 °C for 5 min. Upon reaching the desired mass, the electrode was calcined at 450 °C for 1 h.

Antimony doped tin oxide (ATO) with high surface area was synthesized using a combined sol–gel and hydrothermal method described in our previous work. 1.28 g of tetradecylamine (TDA, CH₃(CH₂)₁₃NH₂, 95%, Sigma Aldrich) was dissolved in ethanol solution (EtOH 65 mL, D.I. water 160 mL) and the stirring was continued for 3 hour. 4.794 g of tin tetrachloride (SnCl₄, 99.995%, Sigma Aldrich) and 0.48 g of antimony(iii) acetate ((CH₃CO₂)₃Sb, 99.99%, Sigma Aldrich) were dissolved in 20 mL of ethanol followed by adding into the TDA solution. After stirring for 1 hour, the mixture was added to 200 mL ammonium hydroxide solution (1.5 mmol L^–1). The resulting suspension was refluxed for 72 hour at 80 °C and then cooled down to room temperature. The white precipitate was separated with solution by centrifugation (8200 rpm, 15 min), and then washing was repeated 5 times with water. The as-prepared wet sample was transferred to a glass-lined stainless-steel autoclave and hydrothermally treated at 120 °C for 24 hour. To remove the excess surfactant, final product was centrifuged and washed with ethanol–water (volume ratio 1 : 1) for 5 times. Produced bright yellow powder was dried in a freeze dryer and then calcined at 400 °C for 3 hour in air condition.

All aldehydes (1 to 56) were purchased from Sigma Aldrich Chemical Co. and used as received without further purification. Cyclic anhydrides (A to E) were purchased from Aladdin Reagent Company (Shanghai) and sublimated twice before use. Catalysts including BF₃•Et₂O, B(C₆F₅)₃, Bu₂BOTf, SnCl₄, InBr₃, MeOTf, and NH(OTf)₂ were purchased from Sigma Aldrich Chemical Co. and used as received.

Polyvinylpyrrolidone (PVP, Average Mw~1,300,000 g/g mol, Sigma Aldrich, St. Louis, MO, USA) was used as received. Indium chloride (InCl₃, 4H₂O) (>97% purity) and tin chloride (SnCl₄, 5H₂O) (Sigma Aldrich, USA) were used as inexpensive precursor materials for the fabrication of ITO fibers. A mixed solvent of ethanol (EtOH) (>99.5% pure) (Fischer Scientific, Hampton, NH, USA) and N, N-dimethyl formamide (DMF) (Sigma Aldrich, USA) was used for the preparation of PVP-InCl₃-SnCl₄ sol solution for spinning. These chemicals were used without further purification.