Tempo

RG powder (5 g) was stirred in purified water (100 ml) containing 0.2 mmol/g of (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO; Alfa Aesar, USA), 2 mmol/g of NaBr (Ducksan, Korea), and 10 mmol/g of NaClO (Daejung, Korea) at pH 10 and room temperature for 24 h. The mixture was maintained at pH 10–11 with 0.5 M NaOH (Ducksan, Korea). After oxidation, 0.175 ml of ethanol (Ducksan, Korea) was added to quench the reaction, and the pH of the mixture was adjusted to 6 with 1 M HCl (Ducksan, Korea). The mixture was washed with ethanol and purified water, then it is fibrillated using a microfluidizer (Microfluidics corporation, USA) and concentrated, followed by dispersing it in water and vacuum evaporating (Buchi, Switzerland) at 70°C to form the gel.

CO₂ (>99.95%) was provided by Beijing Analysis Instrument Factory. DMF and trifluoroacetate were provided by Beijing Chemical Reagent Company. DMA and NMP were purchased from J&K Scientific Co., Ltd. Cu(OAc)₂·H₂O (A. R. Grade) was purchased from Alfa Aesar. H₃BTC (purity 95%) was provided by Aldrich. Benzene dicarboxylic acid (H₂BDC, 98%), MnCl₂ (97%), methyl ammonium (30 wt% H₂O₂), benzyl alcohol (99%), cinnamyl alcohol (98%) and TEMPO (purity 98%) were supplied by Alfa Aesar. 3-Nitrobenzyl alcohol, 4-methylbenzyl alcohol and 3,3′,5,5′-tetrakis(trifluoromethyl)benzhydrol (purity 97%) were purchased from J&K Scientific Co., Ltd. Sodium carbonate was provided by Beijing Chemical Reagent Company. The methyl ammonium salt of the ligand H₂BDC was made by dissolving the benzene dicarboxylic acid in a 40 wt % solution of methyl amine in water. The excess methyl amine and water were evaporated under reduced pressure, and the isolated salt was then redissolved in distilled water to give an aqueous solution of desired concentration.