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.
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.
Fabricating new and efficient materials aimed at containment of water contamination, in particular removing toxic heavy metal based oxo-anions (e. g. CrO 42À , TcO 4 À ) holds paramount importance. In this work, we report two new highly stable imidazolium based ionic porous organic polymers (iPOPs) decorated with multiple interaction sites along with electrostatics driven adsorptive removal of such oxoanions from water. Both the iPOPs (namely, iPOP-3 and iPOP-4) exhibited rapid sieving kinetics and very high saturation uptake capacity for CrO 4 2À anions (170 and 141 mg g À 1 for iPOP-3 and iPOP-4 respectively) and ReO 4 À (515.5 and 350.3 mg g À 1 for iPOP-3 and iPOP-4 respectively), where ReO 4 À anions being the non-radioactive surrogative counterpart of radioactive TcO 4 À ions. Noticeably, both iPOPs showed exceptional selectivity towards CrO 4 2À and ReO 4 À even in presence of several other concurrent anions such as Br À , Cl À , SO 4 2À , NO 3 À etc. The theoretical binding energy calculations via DFT method further confirmed the preferential interaction sites as well as binding energies of both iPOPs towards CrO 4 2À and ReO 4À over all other competing anions which corroborates with the experimental high capacity and selectivity of iPOPs toward such oxo-anions.
In recent years, the synthesis of xanthone derivatives has attracted special attention due to their many biological activities specially as antitumour agents 1 A small liophilic substituent at the C-5 position of xanthone-4-acetic acid enhances the dose potency as an antitumour agent. 2 The antibiotic bikaverin, 3,4 which contains benzo [b]xanthone skeleton, has a high vacuolation property and is a fungal metabolite. Recently, a number of glycosides linked at the 2-position to 4, 5, 8-trimethoxyxanthone have been isolated from ethanolic solution of rhizome of A. Calamus. 5 In view of the natural occurrence and useful range of biological activity associated with the xanthone moiety, various methods have been developed for their syntheses. Most syntheses have been carried out from benzene derivatives and a few from benzopyran-4-ones. 6 We intended to couple 3-functionalised 4-oxo-4H-1benzopyrans through their 2-positions. This coupled product could serve as a precursor for many oxygenerated polycyclic compounds. We have recently reported 7 that 3formylchromenone 1 fails to produce the desired coupled product when treated with sodium naphthalenide or zinc. Product formation was rationalised by considering the initial addition of electron to the aldehyde function of 1 rather at C-2 of the chromenone moiety. Treatment acetal 2 of sodium naphthalenide produced the same mixture of products as was obtained from 1. An earlier report 8 showed that reactions of nucleophiles either with 1 or with 2 produce the same products. Reaction of sodium naphthalenide with ketone 3 produced 2-salicyloylxanthone as was obtained from base-catalysed transformation of 3. 9 Hydrodimerisation of α, β-unsaturated esters 10 by SmI 2 , cyclodimerisation of α, β-unsaturated esters to cyclopentanone derivatives by Yb 11 or by sodium naphthalenide 12 are known. We used 3-methoxycarbonyl-4-oxo-4H-1-benzopyran 4 as the substrate.
Large-scale nuclear power plant production of iodine radionuclides ( 129 I, 131 I) pose huge threat in the events of nuclear disaster. Effective removal of radioiodine from nuclear waste is one of the most critical challenge because of the drawbacks of state-of-the-art adsorbents such as high cost, low uptake capacity and non-recyclability. Herein, two hydroxy-functionalized (-OH) hypercrosslinked polymers (HCPs), namely HCP-91 and HCP-92, have been synthesized and employed towards capture of iodine. High chemical stability along with synergistic harmony of high porosity and functionality of these materials makes them suitable candidates for capture of iodine from both vapor phase and water medium. Moreover, both the HCPs showed superior iodine removal performance from water in terms of fast kinetics and high removal efficiency (2.9 g g À 1 and 2.49 g g À 1 for HCP-91 and HCP-92 respectively). The role of functionality (-OH groups) and porosity has been established with the help of HCP-91, HCP-92 and non-functionalized biphenyl HCP for the efficient capture of I 3 ̄ions from water. In addition, both HCPs exhibited excellent selectivity and recyclability towards triiodide ions, rendering the potential of these materials towards real-time applications. Lastly, Density functional theoretical studies revealed key insights and corroborate well with the experimental findings.
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