Linking Nitrogen-Rich Organic Cages into Isoreticular Covalent Organic Frameworks for Enhancing Iodine Adsorption Capability

Abstract

By linking a nitrogen-rich organic cage with linear connectors, three cage-based isoreticular covalent organic frameworks, i.e., Cage-IRCOF-1, Cage-IRCOF-2, Cage-IRCOF-3, were successfully designed and synthesized by Schiff-base polycondensation reactions. The structure determination and simulations from powder X-ray diffraction measurements indicated that these COFs have high crystallinity derived from the packing of covalently linked two-dimensional isoreticular layer frameworks. As nitrogen-rich porous materials, iodine capture studies were carried out, proving that they displayed obvious enhancements in iodine uptake as compared with the pristine cage itself. In particular, Cage-IRCOF-1 displayed an iodine adsorption capacity of 262 wt %, which is 12 times higher than the solid packed from the cage itself. Spectral studies revealed that there were strong interactions between the nitrogen-rich groups and the adsorbed iodine species. This work demonstrated that linking the discrete organic cages into reticular crystalline frameworks, effective adsorbents can be fabricated for targeted applications.

[M8L4]8+-Type Squares Self-Assembled by Dipalladium Corners and Bridging Aromatic Dipyrazole Ligands for Iodine Capture

“…In addition, the species of captured iodine were further detected by Raman spectroscopy. As shown in Figure d, compared with the original 4· 8NO 3 – , strong peaks at 112 and 167 cm –1 for I 2 @ 4· 8NO 3 – attributed to the stretching vibrations of I 3 – and I 5 – anions, respectively, were then also observed . Thus, the results show that the adsorbed iodine species in metallamacrocycles exist as both iodine molecules and polyiodine species.…”

“…Thus, the results show that the adsorbed iodine species in metallamacrocycles exist as both iodine molecules and polyiodine species. According to the literature reports, , the generation of the I 3 – and I 5 – species should be attributed to the charge transfer between the adsorbed electron-deficient iodine and electron-rich groups such as aromatic including phenyl, naphthyl, and anthranyl in the adsorbents. − The 1 H NMR spectra, XPS spectra, Raman spectra, and FT-IR spectra of the other complexes are shown in the Supporting Information.…”

Efficient Iodine Uptake of Ultra Thermally Stable Conjugated Copolymers Bearing Biaceanthrylenyl Moieties and Contorted Aromatic Units Using a [3 + 2] Palladium-Catalyzed Cyclopolymerization Reaction

“…Interestingly, the hitherto stated adsorption values did not change even after 72 h, therefore indicating that the copolymers were saturated with iodine. The iodine adsorption capacity recorded for BCP2 outperforms many copolymers reported in the literature, including nitrogen-abundant covalent organic frameworks (2620 mg g –1 ), copper-containing zeolites (450 mg g –1 ), nitrogen-rich thorium nanotube materials (955 mg g –1 ), metalorganic copolymers (2360 mg g –1 ), conjugated porous materials (1660 mg g –1 ), porous carbon materials (955 mg g –1 ), and conjugated polymers (2000 mg g –1 ) . The adsorbed I2 was desorbed by warming the iodine-loaded copolymers ( BCP1–3@I2 ) in air at 125 °C, and the desorption efficiency was calculated at various time periods and found to be quantitative as shown in Figure b.…”

Structural Modulation of Nitrogen-Rich Covalent Organic Frameworks for Iodine Capture

“…The ordered 1D nanochannels in the COFs are conducive for facile guest enrichment. Furthermore, the adsorption affinity toward iodine can be augmented by the easy functional tunability of the building units in tailor-made COFs, making them distinctive from traditional iodine-adsorbing materials. − Liu and co-workers have demonstrated a porosity modulation approach in two-dimensional COFs (2D COFs) to achieve better iodine uptake performance . Ma and co-workers deciphered the vital role of the flexibility of the framework in augmenting volatile iodine capture .…”