Arunabha Sen

Two porous hydrogen-bonded organic frameworks (HOFs) based on arene sulfonates and guanidinium ions are reported. As a result of the presence of ionic backbones appended with protonic source, the compounds exhibit ultra-high proton conduction values (σ) 0.75× 10(-2) S cm(-1) and 1.8×10(-2) S cm(-1) under humidified conditions. Also, they have very low activation energy values and the highest proton conductivity at ambient conditions (low humidity and at moderate temperature) among porous crystalline materials, such as metal-organic frameworks (MOFs) and covalent organic frameworks (COFs). These values are not only comparable to the conventionally used proton exchange membranes, such as Nafion used in fuel cell technologies, but is also the highest value reported in organic-based porous architectures. Notably, this report inaugurates the usage of crystalline hydrogen-bonded porous organic frameworks as solid-state proton conducting materials.

Large-scale generation of radioactive iodine (129I, 131I) in nuclear power plants pose a critical threat in the event of fallout, thus rendering the development of iodine sequestering materials (from both the vapor and aqueous medium) highly pivotal. Herein, we report two chemically stable ionic polymers containing multiple binding sites, including phenyl rings, imidazolium cations, and bromide anions, which in synergy promote adsorption of iodine/triiodide anions. In brief, exceptional iodine uptake (from the vapor phase) was observed at nuclear fuel reprocessing conditions. Furthermore, the ionic nature propelled removal of >99% of I3– from water within 30 min. Additionally, benchmark uptake capacities, as well as unprecedented selectivity, were observed for I3–anions. The excellent affinity (distribution coefficient, ∼105 mL/g) enabled iodine capture from seawater-spiked samples. Moreover, iodine-loaded compounds showed conductivity (10–4 S/cm, 10–6 S/cm), placing them among the best known conducting porous organic polymers. Lastly, DFT studies unveiled key insights in coherence with the experimental findings.

Abstract Considering the importance of sustainable nuclear energy, effective management of radioactive nuclear waste, such as sequestration of radioiodine has inflicted a significant research attention in recent years. Despite the fact that materials have been reported for the adsorption of iodine, development of effective adsorbent with significantly improved segregation properties for widespread practical applications still remain exceedingly difficult due to lack of proper design strategies. Herein, utilizing unique hybridization synthetic strategy, a composite crystalline aerogel material has been fabricated by covalent stepping of an amino-functionalized stable cationic discrete metal-organic polyhedra with dual-pore containing imine-functionalized covalent organic framework. The ultralight hybrid composite exhibits large surface area with hierarchical macro-micro porosity and multifunctional binding sites, which collectively interact with iodine. The developed nano-adsorbent demonstrate ultrahigh vapor and aqueous-phase iodine adsorption capacities of 9.98 g.g −1 and 4.74 g.g −1 , respectively, in static conditions with fast adsorption kinetics, high retention efficiency, reusability and recovery.

Abstract Two porous hydrogen‐bonded organic frameworks (HOFs) based on arene sulfonates and guanidinium ions are reported. As a result of the presence of ionic backbones appended with protonic source, the compounds exhibit ultra‐high proton conduction values ( σ ) 0.75× 10 −2 S cm −1 and 1.8×10 −2 S cm −1 under humidified conditions. Also, they have very low activation energy values and the highest proton conductivity at ambient conditions (low humidity and at moderate temperature) among porous crystalline materials, such as metal–organic frameworks (MOFs) and covalent organic frameworks (COFs). These values are not only comparable to the conventionally used proton exchange membranes, such as Nafion used in fuel cell technologies, but is also the highest value reported in organic‐based porous architectures. Notably, this report inaugurates the usage of crystalline hydrogen‐bonded porous organic frameworks as solid‐state proton conducting materials.

Abstract Fabricating new and efficient materials aimed at containment of water contamination, in particular removing toxic heavy metal based oxo‐anions (e. g. CrO 4 2− , TcO 4 − ) holds paramount importance. In this work, we report two new highly stable imidazolium based ionic porous organic polymers ( i POPs) decorated with multiple interaction sites along with electrostatics driven adsorptive removal of such oxo‐anions from water. Both the i POPs (namely, i POP‐3 and i POP‐4) exhibited rapid sieving kinetics and very high saturation uptake capacity for CrO 4 2− anions (170 and 141 mg g −1 for i POP‐3 and i POP‐4 respectively) and ReO 4 − (515.5 and 350.3 mg g −1 for i POP‐3 and i POP‐4 respectively), where ReO 4 − anions being the non‐radioactive surrogative counterpart of radioactive TcO 4 − ions. Noticeably, both i POPs showed exceptional selectivity towards CrO 4 2− and ReO 4 − even in presence of several other concurrent anions such as Br − , Cl − , SO 4 2− , NO 3 − etc. The theoretical binding energy calculations via DFT method further confirmed the preferential interaction sites as well as binding energies of both i POPs towards CrO 4 2− and ReO 4 − over all other competing anions which corroborates with the experimental high capacity and selectivity of i POPs toward such oxo‐anions.