Water Stability. To check the water

Water Stability. To check the water stability, the freshly as-synthesized samples of JXNU-5 were filtered and washed with DMF three times and then soaked in distilled water. After immersion in water for 10 days, the samples were filtered and dried under ambient conditions. The PXRD pattern of the sample treated with water is depicted in Figure S3, which shows that the diffraction peaks of the sample treated with water match well with those of the pristine sample. Thus, the JXNU-5 material can maintain the crystallinity and structural integrity in aqueous solution. Furthermore, N2 adsorption data at 77 K for the sample treated with water for 10 days were collected. The N2 sorption curves of the pristine and water-treated samples overlap at the low-pressure region and display a slight disparity at high pressure (Figure 2), demonstrating JXNU-5 with retention of the porosity after exposure to water. As shown in Figure 2, the saturated N2 uptake for the water-treated sample is 154.3 cm3 (STP) g−1, which is slightly higher than that of the as-synthesized sample. The BET surface area of 425 m2 g−1 for the water-treated sample is larger than that of the as-synthesized sample. Although the whole structural integrity and crystallinity of the compound after soaking in water were retained, few defects in the structure were generated. Such defects in the structure enhance the porosity, which is responsible for the larger N2 uptake and surface area. Finally, the C2H2 and CO2 adsorption data at 298 K for the samples soaked in water for 10 days were further measured. A slight difference was observed in the C2H2 and CO2 adsorption curves for the as-synthesized and water-treated samples (Figure 3b). These results reveal that the gas adsorption performance of JXNU-5a was maintained after exposure to water.