Synthesis of Mn-MOF

Mn-MOF was synthesized by a solvothermal reaction between ZrOCl₂·8H₂O and Mn-TCPP ⁴⁴. To synthesize Mn-TCPP ⁴⁵, 4-carbomethoxybenzaldehyde (16.4 g, 0.1 mol) and pyrrole (6.9 mL, 0.1 mol) in 250 mL of propionic acid were refluxed and stirred for 2 h. The mixture solutions were then cooled to room temperature, and the resultant purple precipitates were filtered and washed with ethanol. The obtained H₂TCPP-OMe was dissolved in CH₂Cl₂ and then purified by silica gel column (200-300 mesh) using CH₂Cl₂ and ethyl acetate (v/v, 100/1) as mobile phase. Furthermore, H₂TCPP-OMe (0.42 g, 0.5 mmol) and MnCl₂·4H₂O (0.49 g, 2.48 mmol) in 50 mL of DMF was refluxed and stirred at 260 °C for 12 h. After cooling to room temperature, DMF was discarded by reduced pressure distillation. The obtained Mn-TCPP-OMe was washed with deionized water three times and dried. Mn-TCPP-OMe (0.44 g, 0.5 mmol) dissolved in 20 mL THF and KOH (1.12 g, 20 mmol) dissolved in 20 mL of deionized water were stirred at room temperature for 72 h. THF was discarded by reduced pressure distillation, and the resulting Mn-TCPP was treated with 2% HCl to adjust pH to 1-2 and washed with deionized water. TCPP was obtained using the same protocol except that TCPP-OMe did not react with MnCl₂·4H₂O. The chemical structures of TCPP and Mn-TCPP were determined by FT-IR spectrometer (Equinox55, Bruker, Germany), NMR spectrometer (600 MHz Bruker AscendTM, Bruker, Germany) and MALDI-TOF/TOF 5800 mass spectrometer (ABSciex, Framingham, MA, USA).

ZrOCl₂·8H₂O (30 mg, 0.093 mmol), benzoic acid (0.28 g, 2.29 mmol) and Mn-TCPP (10.98 mg, 0.013 mmol) were dissolved in 14 mL of DMF and the mixtures were stirred at 90 °C for 5 h. After the reaction, the mixtures were cooled to room temperature and centrifuged at 15, 000 rpm for 15 min. The pellets were washed with fresh DMF for three times and deionized water for three times. The resulting Mn-MOF was suspended in deionized water for further experiments. MOF was synthesized according to the same procedure except adding TCPP instead of Mn-TCPP.