Showing papers on "Iodine published in 2022"

Adsorption of iodine in metal–organic framework materials

Abstract: Nuclear power will continue to provide energy for the foreseeable future, but it can pose significant challenges in terms of the disposal of waste and potential release of untreated radioactive substances. Iodine is a volatile product from uranium fission and is particularly problematic due to its solubility. Different isotopes of iodine present different issues for people and the environment. 129I has an extremely long half-life of 1.57 × 107 years and poses a long-term environmental risk due to bioaccumulation. In contrast, 131I has a shorter half-life of 8.02 days and poses a significant risk to human health. There is, therefore, an urgent need to develop secure, efficient and economic stores to capture and sequester ionic and neutral iodine residues. Metal–organic framework (MOF) materials are a new generation of solid sorbents that have wide potential applicability for gas adsorption and substrate binding, and recently there is emerging research on their use for the selective adsorptive removal of iodine. Herein, we review the state-of-the-art performance of MOFs for iodine adsorption and their host–guest chemistry. Various aspects are discussed, including establishing structure–property relationships between the functionality of the MOF host and iodine binding. The techniques and methodologies used for the characterisation of iodine adsorption and of iodine-loaded MOFs are also discussed together with strategies for designing new MOFs that show improved performance for iodine adsorption.

Eutectic electrolyte based on N-methylacetamide for highly reversible zinc–iodine battery

Abstract: A eutectic electrolyte strategy is proposed for zinc-iodine battery. Both the reasonable solvated structure and suppressed generation of I3− as an intermediate product achieve the high reversible I−/I0 conversion.

Precise fabrication of porous polymer frameworks using rigid polyisocyanides as building blocks: from structural regulation to efficient iodine capture

Abstract: Porous materials have recently attracted much attention owing to their fascinating structures and broad applications. Moreover, exploring novel porous polymers affording the efficient capture of iodine is of significant interest. In contrast to the reported porous polymers fabricated with small molecular blocks, we herein report the preparation of porous polymer frameworks using rigid polyisocyanides as building blocks. First, tetrahedral four-arm star polyisocyanides with predictable molecular weight and low dispersity were synthesized; the chain-ends of the rigid polyisocyanide blocks were then crosslinked, yielding well-defined porous organic frameworks with a designed pore size and narrow distribution. Polymers of appropriate pore size were observed to efficiently capture radioactive iodine in both aqueous and vapor phases. More than 98% of iodine could be captured within 1 minute from a saturated aqueous solution (capacity of up to 3.2 g g−1), and an adsorption capacity of up to 574 wt% of iodine in vapor was measured within 4 hours. Moreover, the polymers could be recovered and recycled for iodine capture for at least six times, while maintaining high performance.

Accelerated Degradation of Perfluorosulfonates and Perfluorocarboxylates by UV/Sulfite + Iodide: Reaction Mechanisms and System Efficiencies

Abstract: The addition of iodide (I–) in the UV/sulfite system (UV/S) significantly accelerated the reductive degradation of perfluorosulfonates (PFSAs, CnF2n+1SO3–) and perfluorocarboxylates (PFCAs, CnF2n+1COO–). Using the highly recalcitrant perfluorobutane sulfonate (C4F9SO3–) as a probe, we optimized the UV/sulfite + iodide system (UV/S + I) to degrade n = 1–7 PFCAs and n = 4, 6, 8 PFSAs. In general, the kinetics of per- and polyfluoroalkyl substance (PFAS) decay, defluorination, and transformation product formations in UV/S + I were up to three times faster than those in UV/S. Both systems achieve a similar maximum defluorination. The enhanced reaction rates and optimized photoreactor settings lowered the EE/O for PFCA degradation below 1.5 kW h m–3. The relatively high quantum yield of eaq– from I– made the availability of hydrated electrons (eaq–) in UV/S + I and UV/I two times greater than that in UV/S. Meanwhile, the rapid scavenging of reactive iodine species by SO32– made the lifetime of eaq– in UV/S + I eight times longer than that in UV/I. The addition of I– also substantially enhanced SO32– utilization in treating concentrated PFAS. The optimized UV/S + I system achieved >99.7% removal of most PFSAs and PFCAs and >90% overall defluorination in a synthetic solution of concentrated PFAS mixtures and NaCl. We extended the discussion over molecular transformation mechanisms, development of PFAS degradation technologies, and the fate of iodine species.

A renewable biomass-based lignin film as an effective protective layer to stabilize zinc metal anodes for high-performance zinc-iodine batteries

Abstract: Aqueous rechargeable zinc-iodine (Zn-I2) batteries with high security and low cost have been considered as a promising candidate for energy storage instruments in recent years. Nevertheless, the commercial application of...

Bisindole [3]arenes—Indolyl Macrocyclic Arenes Having Significant Iodine Capture Capacity

Abstract: Open AccessCCS ChemistryRESEARCH ARTICLE1 May 2022Bisindole [3]arenes—Indolyl Macrocyclic Arenes Having Significant Iodine Capture Capacity Xingke Yu, Wanhua Wu, Dayang Zhou, Dan Su, Zhihui Zhong and Cheng Yang Xingke Yu Key Laboratory of Green Chemistry and Technology of Ministry of Education, College of Chemistry, State Key Laboratory of Biotherapy and Healthy Food Evaluation Research Center, Sichuan University, Chengdu 610064 Google Scholar More articles by this author , Wanhua Wu *Corresponding authors: E-mail Address: [email protected] E-mail Address: [email protected] Key Laboratory of Green Chemistry and Technology of Ministry of Education, College of Chemistry, State Key Laboratory of Biotherapy and Healthy Food Evaluation Research Center, Sichuan University, Chengdu 610064 Google Scholar More articles by this author , Dayang Zhou Comprehensive Analysis Center, ISIR, Osaka University, Mihogaoka, Ibaraki 567-0047 Google Scholar More articles by this author , Dan Su Key Laboratory of Green Chemistry and Technology of Ministry of Education, College of Chemistry, State Key Laboratory of Biotherapy and Healthy Food Evaluation Research Center, Sichuan University, Chengdu 610064 Google Scholar More articles by this author , Zhihui Zhong Key Laboratory of Green Chemistry and Technology of Ministry of Education, College of Chemistry, State Key Laboratory of Biotherapy and Healthy Food Evaluation Research Center, Sichuan University, Chengdu 610064 Google Scholar More articles by this author and Cheng Yang *Corresponding authors: E-mail Address: [email protected] E-mail Address: [email protected] Key Laboratory of Green Chemistry and Technology of Ministry of Education, College of Chemistry, State Key Laboratory of Biotherapy and Healthy Food Evaluation Research Center, Sichuan University, Chengdu 610064 Google Scholar More articles by this author https://doi.org/10.31635/ccschem.021.202101036 SectionsSupplemental MaterialAboutAbstractPDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareFacebookTwitterLinked InEmail Several novel macrocyclic arenes that are composed of six indole subunits, so-called bisindole[3]arenes (BID[3]s), were conveniently synthesized by the aluminum trichloride-catalyzed one-pot condensation of bisindole derivatives and paraformaldehyde in dichloromethane at room temperature. Their macrocyclic structures were demonstrated by X-ray single-crystal studies, and the presence of the macrocyclic cavities made it possible to accommodate specific small organic molecules. The BID[3]s have exceptionally high iodine adsorption ability due to the strong and synergic interaction of indole units toward iodine, exhibiting significant morphology changes upon adsorption and desorption of iodine. Iodine uptake capacity of up to 5.12 g·g−1 was found with MeBID[3], which is the highest value ever reported for macrocyclic arenes. Download figure Download PowerPoint Introduction The importance of fission reactors in nuclear power plants as energy resources has been continuously growing. One of the major environmental pollutants of nuclear plants is the volatile radioactive iodine, including 131I and 129I, which quickly diffuses into the air and creates safety concerns due to the extremely long radioactive half-life of 129I (1.57 × 107 years) or short-lived but accumulable and metabolism-influencing 131I.1–4 The capture of radioactive iodine with metal-exchanged zeolites is the prevalent technique in the industry, which suffers from low uptake capacity.5,6 Various novel type absorbents, such as metal–organic frameworks,7–10 covalent organic frameworks,11–15 macrocyclic compounds, activated carbon,16,17 and zeolites,18,19 have recently emerged. In particular, macrocyclic compounds have attracted increasing attention due to their favorable aromatic ring-iodine complexation, their thermal and chemical stability, and the feasibility of processing them.20–25 Recent representative examples include pillar[6]arene23 biphenyl[n]arenes,24 and functionalized leaning-tower[6]arenes,25 which showed an iodine adsorption capacity of 0.25, 0.67, and up to 2.08 g·g−1, respectively. These studies demonstrate the promising potential of macrocyclic arenes for iodine adsorption besides their significant roles in supramolecular and host–guest chemistry.26–30 The charge-transfer interaction of iodine with aromatic compounds plays a significant role in the uptake of iodine by macrocyclic arenes.31,32 On the other hand, studies on exploring new macrocyclic arenes have recently grown rapidly, producing a variety of new macrocyclic compounds, such as leaning-pillar[6]arene,33 prismarenes,34 pagoda[4]arene,35 diphenylamine[n]arenes,36 and pagoda[5]arenes.37 Most known macrocyclic arenes are based on electron-enriched aromatic hydrocarbon units, such as phenol derivatives, while only a few were composed of heteroaromatic rings-based subunits.38–42 Indole is a π-electron-rich heteroaromatic ring with a unique ring structure and electron donor–acceptor properties, which forms a charge-transfer complex with iodine and stability constants overwhelmingly higher than common aromatic hydrocarbons.31,43 As a continuation of our studies on supramolecular self-assembly,44–48 we launched the construction of novel indole-based macrocyclic arenes and report herein their significantly high absorption ability toward iodine. Experimental Methods In this study, all reagents were purchased commercially and used without further purification unless otherwise noted. Iodine (99.99%) was purchased from ADAMAS-BETA (Shanghai, China). 1H and 13C NMR spectra were recorded at room temperature on a Bruker AMX-400 (Bruker, Germany) (operating at 400 MHz for 1H NMR and 101 MHz for 13C NMR) with tetramethylsilane (TMS) as the internal standard. High-resolution mass spectrometry (HRMS) data were measured with a Waters Q-TOF Premier (Waters, USA) electrospray ionization mass spectrometry or a matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) spectrometer. UV–vis spectra were recorded by using a JASCO V650 (JASCO, Japan) spectrometer. Fluorescence spectra were taken on a JASCO FP-8500 (JASCO, Japan) spectrofluorometer, and the bandwidth for the measurement was not fixed. Fourier transform infrared (FT-IR) spectra were recorded as KBr pellets on a NEXUS 670 (Thermo Nicolet, USA) FTIR spectrometer. Thermogravimetric analysis (TGA) was carried out using a Shimadzu DTG-60 (Shimadza, Japan) instrument, and the samples were heated under nitrogen gas at a rate of 10 °C/min. Powder X-ray diffraction (PXRD) data were measured with a powder X-ray diffractometer (X’ Pert Pro MPD DY129, Malvern Pananalytical, Shanghai, China) at a range 5–60° of 2θ. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) investigations were carried out on JSM-5900LV (JEOL, Tokyo, Japan). N2 adsorption isotherms measurements were performed with a QUADRASORB (Anton Paar, USA) instrument at 87 K. Melting points were measured with a digital melting point apparatus (WRS-1B, Yidian, Shanghai, China). More experimental details and characterization of products are available in the Supporting Information. Results and Discussion Synthesis and characterizations of BID[3]s The attempt to synthesize indolyl macrocycles by reacting indole with paraformaldehyde yielded cyclic trimers condensed at the indole′s 2′ and 3′ positions, which bore only a small, bowl-like cavity ( Supporting Information Figures S7 and S8).49 However, condensation of bisindole derivatives 1a–1c (Scheme 1, Supporting Information Figures S1–S6), synthesized by reacting corresponding indole derivatives with dibromomethane or methylene chloride in the presence of sodium hydride, with paraformaldehyde under the catalysis of aluminum trichloride, led to the bisindole[3]arenes (BID[3]s) in yields of 4.8–10.3%. Other Lewis acid catalysts such as ferric chloride and boron trifluoride ether were also tried, but no macrocyclic compound was formed. BID[3], MeBID[3], and MeOBID[3] (Scheme 1) showed the [M–H]− peaks at m/z 773.3948, 857.4564, and 953.4167, respectively, in the MALDI-TOF MS spectra ( Supporting Information Figures S28–S30). All BID[3]s contained six indole units, but only 5, 4, and 4 kinds of aromatic protons were observed in 1H NMR spectra of BID[3], MeBID[3], and MeOBID[3] ( Supporting Information Figures S15–S20), respectively, which coincided with the C3v-symmetry structures of BID[3]s. Scheme 1 | The synthesis of 1a–1c, BID[3], MeBID[3], and MeOBID[3]. Download figure Download PowerPoint By the solvent-evaporation method in the mixed solvents of chloroform and methylbenzene or single solvent of N,N-dimethylformamide, the single crystals of the macrocycles BID[3] and MeBID[3] were successfully grown, respectively. The X-ray single-crystal analyses revealed that the six indole units of BID[3] (Figures 1a and 1c, Supporting Information Figures S36) alternatively pointed upward and downward relative to the annulus plane of the macrocycle. The distances between the carbon or nitrogen atom of the symmetrical indole units were 7.44–9.22 Å, suitable for accommodating a small organic molecule. On the contrary, the methylindole units in MeBID[3] were arranged in an orderly petal-like fashion, and the cavity shrunk significantly as all methyl groups inclined directly toward the cavity (Figures 1b and 1d, Supporting Information Figures S37). CH···π interactions played an important role in the packing structure of BID[3], showing CH···aromatic plane distances of 2.59 and 2.67 Å, respectively ( Supporting Information Figures S38). On the contrary, the unit cell in the crystal structure of MeBID[3] showed a relatively disorganized arrangement (Figure 1d). The CH···π interaction (2.68 Å) and intermolecular π···π interaction (4.49 Å) are also shown in the packing diagram of MeBID[3] ( Supporting Information Figures S39). Figure 1 | Crystal structures of (a) BID[3] and (b) MeBID[3] in top and side view, and the packing mode of (c) BID[3] and (d) MeBID[3]. C, gray; H, white; N, blue; solvent and the hydrogen atoms were omitted for clarity.a Download figure Download PowerPoint Iodine vapor capture by BID[3]s The TGA revealed that there was no apparent weight loss from 20 to 267 °C for MeBID[3]. BID[3] and MeOBID[3] were stable even at a temperature higher than 300 °C ( Supporting Information Figures S49–S51). Moreover, BID[3]s showed high melting points of >300, 266.2, and 281.8 °C for BID[3], MeBID[3], and MeOBID[3], respectively, while all indole subunits had melting points lower than 60 °C.50–52 This should allow BID[3]s to be used in the high-temperature environment of the nuclear power plant. The uptake of iodine vapor with BID[3]s was thus examined by placing the solid powder of BID[3]s in preweighed vials and then exposing the powder vials to iodine vapor in a sealed container in an oven at 75 °C. After exposure to iodine vapor, the BID[3]s powders gradually deepened in color over time (Figure 2b). The adsorption iodine over time was weighed after cooling the iodine-loaded samples down to room temperature. As illustrated in Figure 2a, the uptake values of iodine increased with time, and BID[3], MeBID[3], and MeOBID[3] reached saturation adsorption at ca. 25, 12, and 10 h, respectively. Excitingly, all three BID[3]s showed strong absorption of iodine vapor, and uptake ratios (wt/wt) of 4.49 4.73, and 5.12 g·g−1 were observed for MeOBID[3], BID[3], and MeBID[3], respectively, which is by far the largest unit iodine uptake capacity by macrocyclic compounds ever reported ( Supporting Information Figures S69). Meanwhile, such uptake ratios mean that on average 2.41, 2.67 and 2.81 iodine molecules were attached per indole unit for BID[3], MeBID[3] and MeOBID[3], respectively, demonstrating that the iodine molecules should not just be complexed at the inner cavity of BID[3]s but also on the exterior side of the cavity, presumably through the exterior wall synergy. Moreover, compared to the indole-derived polymers, which showed an uptake capacity up to 0.66 g·g−1 by virtue of the electron-rich frameworks,53 the iodine uptake capacity with MeBID[3] was approximatively eight times higher, further confirming the importance of macrocyclic synergism. Figure 2 | (a) Time-dependent I2 vapor uptake profiles of BID[3], MeBID[3], and MeOBID[3] at 75 °C. (b) The photographs of BID[3]s upon I2 vapor uptake at varying time intervals, and FT-IR spectra of (c) BID[3], (d) MeBID[3, and (e) MeOBID[3] before (black line) and after adsorption of iodine vapor (red line). Download figure Download PowerPoint The high uptake values were exceptional compared to the values reported with known macrocyclic arenes.20–24 To shed light on the mechanism of the significant uptake capacity, we examined the pore performance of macrocycles by the physical adsorption of nitrogen at 77 K ( Supporting Information Figures S46–S48). The gradual increase and decrease of the adsorption and desorption curves for the adsorption and desorption processes, respectively, indicated the type-III adsorption isotherm. The specific surface areas were primarily low, showing 5.18 m2·g−1 for BID[3], 7.79 m2·g−1 for MeBID[3], and 1.78 m2·g−1 for MeOBID[3]. These results revealed that the BID[3]s are hardly porous in the crystalline state, which is similar to pillar[n]arenes in the solid-state.23 The initial nonporous structures of BID[3]s should change significantly to adaptively accommodate the iodine molecules. FT-IR spectroscopy of BID[3]s varied visibly after the uptake of iodine (Figures 2c–2e). For MeOBID[3] as an example, the skeletal vibrations of the indole rings (1618.75 and 1579.79 cm−1) and the stretching of the C–N bonds (1285.12 and 1166.56 cm−1) vanished or became weak after the uptake of iodine (Figure 2e). This suggested that the indole subunits exist in diverse circumstances after the adsorption of iodine, which is also supported by the PXRD studies (Figures 3a, 3c, and 3e). The PXRD profiles of BID[3] and MeBID[3] showed sharp diffraction peaks (Figures 3a and 3c), indicating good crystallinity in the solid-state. On the contrary, MeOBID[3] appeared to be amorphous in the solid-state because its diffractogram was a rather broad peak centralized around 20° (Figure 3e). However, after the uptake of iodine, the PXRD of all three BID[3]s showed no clear diffraction peaks assignable to BID[3]s or iodine, demonstrating the loss of the crystalline structure of BID[3]s and good dispersion of iodine molecules in I2⊂BID[3]s. Figure 3 | X-ray powder diffractogram (upper planes) and TGA profiles (lower planes) of BID[3] and I2⊂BID[3] (a and b), MeBID[3] and I2⊂MeBID[3] (c and d), and MeOBID[3] and I2⊂MeOBID[3] (e and f). Download figure Download PowerPoint TGA analyses of the iodine-saturated I2⊂BID[3]s samples indicated that the adsorbed iodine could be released upon heating. The I2⊂BID[3] and I2⊂MeOBID[3] exhibited a mass loss of 81.5% and 81.0%, respectively, after heating to 300 °C, and I2⊂MeBID[3] showed a mass loss of 82.4% at 265 °C (Figures 3b, 3d, and 3f). The results suggested an incomplete release of iodine. Indeed, the EDS measurements also revealed the residue of a certain amount of iodine from the heated I2⊂BID[3]s ( Supporting Information Figures S75–S77). These results further demonstrated the strong interaction of iodine with BID[3]s. SEM studies indicated that BID[3] and MeBID[3] are microcrystals in the shape of rod and sheet, respectively, while MeOBID[3] appeared non-crystalline (Figures 4a, 4d, and 4g), which is consistent with the PXRD study results. It is interesting to find that upon iodine adsorption, the powder of BID[3]s showed apparent changes in its morphology (Figures 4b, 4e, and 4h). The fine powders of BID[3]s were transformed into small blocky solids. In particular, I2⊂MeBID[3] became a sticky liquid-like lump after the uptake of iodine (Figure 4e), suggesting that MeBID[3] and iodine interdisperse to thus break the initial crystalline structure. However, MeBID[3] showed a porous morphology after the desorption of iodine from I2⊂MeBID[3] (Figure 4f). Such a significant morphology change due to absorption and desorption of iodine (Figure 4) has not been reported with macrocyclic arenes, for which the breakup of the initial BID[3]’s stacking by the strong and synergic interaction of indole units toward iodine should be responsible. In addition, the blue emission of MeOBID[3] in the solid-state was completely quenched after the uptake of iodine, presumably due to the charge transfer interaction between indole and iodine (Figure 5a, Supporting Information Figure S35). Figure 4 | SEM images of BID[3]s, I2⊂BID[3]s and after the release of iodine from I2⊂BID[3]s for BID[3] (a–c), MeBID[3] (d–f), and MeOBID[3] (g–i). Download figure Download PowerPoint Iodine release from iodine-loaded macrocyclic arenes All BID[3]s are insoluble in water, which is applicable to the extraction of iodine from an aqueous iodine solution. As shown in Figure 5c, the solid sample of MeBID[3] (5.0 mg) was suspended in the yellow aqueous iodine solution (1.0 mM), and the solution became colorless upon stirring over 0–370 minutes. The time-dependent UV-vis spectra of iodine in water (1.0 mM) gradually decreased with time in the presence of MeBID[3] (Figures 5b and 5c). The residual iodine in water measured after 21 h was 10, 26, and 32 ppm, respectively, for MeBID[3], BID[3], and MeOBID[3] ( Supporting Information Figures S52 and S53). Also, the adsorbed iodine could be primarily removed (>84%) after heating the sample at 100 °C under vacuum for 4 h. Such uptake/release could be carried out for several cycles without losing the performance (Figure 5d). On the other hand, the adsorbed iodine could be completely released by putting the I2⊂BID[3]s in a methanol solution within 50–100 min (Figures 5eand 5f, Supporting Information Figures S70 and S71), and BID[3]s could be primarily recycled due to the poor solubility of BID[3]s in methanol ( Supporting Information Figure S78). Figure 5 | (a) Photos of MeOBID[3] and I2⊂MeOBID[3] under a UV lamp (365 nm) in the light and dark. (b) Time-dependent UV/vis spectra of aqueous I2 solution (1.0 mM) after the addition of MeBID[3] (5.0 mg). (c) Color change of the aqueous I2 solution (1.0 mM) after the addition of MeBID[3] powder (5.0 mg). (d) I2 adsorption/desorption cycles of MeBID[3]. (e) Time-dependent UV/vis spectral changes after adding 0.5 mg I2⊂MeBID[3] in 10.0 mL methanol. (f) Photographs of iodine release of 10.0 mg I2⊂MeBID[3] in 5.0 mL methanol. Download figure Download PowerPoint Conclusion In this study, we have designed and synthesized several brand-new indole-based macrocyclic arenes through aluminum trichloride-catalyzed one-pot condensation. The BID[3]s showed extremely high iodine uptake capabilities at either the aqueous solution or the vapor phase, with MeBID[3] showing an uptake capacity of up to 5.12 g·g−1, the highest value hitherto reported with macrocyclic arenes. Significant morphology changes were observed before and after iodine adsorption and desorption. The electron-enriched indoles and the well-confined macrocyclic structure provide strong interaction, and intermolecular and intramolecular synergy for binding iodine is presumably responsible for the exceptional uptake behavior. This study provides an ingenious method to construct new macrocyclic arenes and opens up new possibilities for efficient iodine adsorbent with macrocyclic arenes. Footnote a CCDC 2039778 and 2054303 contain the supplementary crystallographic data for this paper. These data are provided free of charge by The Cambridge Crystallographic Data Center. Supporting Information Supporting Information is available and includes experimental details, 1H and 13C NMR spectra of the compounds, UV–vis and fluorescence spectra, TGA, FT-IR spectra, single-crystal X-ray data (PDF), X-ray data of BID[3] and MeBID[3] (CIF), PXRD data, SEM and EDS investigations. Conflict of Interest There is no conflict of interest to report. Funding Information This work was supported by the National Natural Science Foundation of China (nos. 21871194, 21971169, and 21572142) and National Key Research and Development Program of China (no. 2017YFA0505903). 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Google Scholar Previous articleNext article FiguresReferencesRelatedDetails Issue AssignmentVolume 4Issue 5Page: 1806-1814Supporting Information Copyright & Permissions© 2021 Chinese Chemical SocietyKeywordsradioactive iodineiodine uptakemacrocyclic arenehost–guest interactionssupramolecular chemistrybisindole[3]arenesAcknowledgmentsThe authors gratefully acknowledge the test platform of the specialized laboratory, College of Chemistry, Sichuan University, and the Analytical and Testing Center of Sichuan University for instrumental measurements. The authors also acknowledge Prof. L.-J. Ma and Dr. S. Liu of the College of Chemistry, and Prof. P. Wu of the Analytical and Testing Center, Sichuan University. Downloaded 1,392 times PDF DownloadLoading ...

Antiseptic Povidone-Iodine Heals the Grain Boundary of Perovskite Solar Cells.

Abstract: Povidone, also know as polyvinylpyrrolidone (PVP), is used as a reservoir for iodine, and the povidone-iodine (PVP-I) complex has antiseptic properties for wound healing by releasing iodine. In this report, we utilized this unique characteristic of PVP-I to heal the photovoltaic parameters of perovskite solar cells (PSCs). PVP-I was added in the perovskite precursor solution, where the effect of the PVP-I concentration on the photovoltaic performance was investigated. The power conversion efficiency (PCE) of PSC was enhanced from 20.73% to 22.59% by addition of 0.1 mg/mL PVP-I, mainly due to an improved fill factor from 0.76 to 0.80 together with a slight increase in current density. Scanning electron microscopy revealed that the grain boundaries were passivated by PVP-I. Conductive atomic force microscopy combined with time-resolved photoluminesence and space charge-limited current studies showed that the addition of PVP-I decreased the defect density of the perovskite film together and enhanced the film conductivity. Furthermore, better stability was observed from the PVP-I-treated PSCs than the control device without the additive, which is probably owing to the grain boundary healing effect.

Progress in organocatalysis with hypervalent iodine catalysts.

Abstract: Hypervalent iodine compounds as environmentally friendly and relatively inexpensive reagents have properties similar to transition metals. They are employed as alternatives to transition metal catalysts in organic synthesis as mild, nontoxic, selective and recyclable catalytic reagents. Formation of C-N, C-O, C-S, C-F and C-C bonds can be seamlessly accomplished by hypervalent iodine catalysed oxidative functionalisations. The aim of this review is to highlight recent developments in the utilisation of iodine(III) and iodine(V) catalysts in the synthesis of a wide range of organic compounds including chiral catalysts for stereoselective synthesis. Polymer-, magnetic nanoparticle- and metal organic framework-supported hypervalent iodine catalysts are also described.

Formation of twelve-fold iodine coordination at high pressure

Abstract: Abstract Halogen compounds have been studied widely due to their unique hypercoordinated and hypervalent features. Generally, in halogen compounds, the maximal coordination number of halogens is smaller than eight. Here, based on the particle swarm optimization method and first-principles calculations, we report an exotically icosahedral cage-like hypercoordinated IN 6 compound composed of N 6 rings and an unusual iodine−nitrogen covalent bond network. To the best of our knowledge, this is the first halogen compound showing twelve-fold coordination of halogen. High pressure and the presence of N 6 rings reduce the energy level of the 5d orbitals of iodine, making them part of the valence orbital. Highly symmetrical covalent bonding networks contribute to the formation of twelve-fold iodine hypercoordination. Moreover, our theoretical analysis suggests that a halogen element with a lower atomic number has a weaker propensity for valence expansion in halogen nitrides.

Realizing compatibility of Li metal anode in all-solid-state Li-S battery by chemical iodine–vapor deposition

Abstract: Artificial solid-electrolyte interlayer (SEI) is extensively used to improve the chemical interfacial stability at the Li/ solid state electrolyte (SSE) interface. However, severe mechanical failures of the SEI, namely, Li...

Synthesis of [1,2,3]Triazolo-[1,5-a]quinoxalin-4(5H)-ones through Photoredox-Catalyzed [3 + 2] Cyclization Reactions with Hypervalent Iodine(III) Reagents.

Abstract: An efficient synthesis of a variety of [1,2,3]triazolo-[1,5-a]quinoxalin-4(5H)-ones via a [3 + 2] cyclization reaction by photoredox catalysis between quinoxalinones and hypervalent iodine(III) reagents is reported. A range of quinoxalinones and hypervalent iodine(III) reagents were tolerated well. This cyclization reaction allows access to structurally diverse [1,2,3]triazolo-[1,5-a]quinoxalin-4(5H)-ones in moderate to good yields.

Physicochemical Confinement Effect Enables High-Performing Zinc-Iodine Batteries.

Abstract: Zinc-iodine batteries are promising energy storage devices with the unique features of aqueous electrolytes and safer zinc. However, their performances are still limited by the polyiodide shuttle and the unclear redox mechanism of iodine species. Herein, a single iron atom was embedded in porous carbon with the atomic bridging structure of metal-nitrogen-carbon to not only enhance the confinement effect but also invoke the electrocatalytic redox conversion of iodine, thereby enabling the large capacity and good cycling stability of the zinc-iodine battery. In addition to the physical trapping effect of porous carbon with good electronic conductivity, the in situ experimental characterization and theoretical calculation reveal that the metal-nitrogen-carbon bridging structure modulates the electronic properties of carbon and adjusts the intrinsic activity for the reversible conversion of iodine via the thermodynamically favorable pathway. This work demonstrates that the physicochemical confinement effect can be invoked by the rational anchoring of a single metal atom with nitrogen in a porous carbon matrix to enhance the electrocatalytic redox conversion of iodine, which is crucial to fabricating high-performing zinc-iodine batteries and beyond by applying the fundamental principles.

Highly Thermally/Electrochemically Stable I−/I3− Bonded Organic Salts with High I Content for Long‐Life Li–I2 Batteries

Abstract: Rechargeable lithium–iodine batteries are highly attractive energy storage systems featuring high energy density, superior power density, sustainability, and affordability owing to the promising redox chemistries of iodine. However, severe thermodynamic instability and shuttling issues of the cathode have plagued the active iodine loading, capacity retention and cyclability. Here the development of highly thermally and electrochemically stable I−/I3−‐bonded organic salts as cathode materials for Li–I2 batteries is reported. The chemical bonding of iodine/polyiodide ions with organic groups allows up to 80 wt% iodine to be effectively stabilized without sacrificing fast and reversible redox reaction activity. Thus, the shuttle effect is significantly inhibited, which improves cathode capacity and restrains side‐reactions on the Li anode. As a result, such cathodes afford Li–I2 batteries a specific capacity of 173.6 mAh g−1methylamine hydroiodide (MAI) (217 mAh g−1I) at 0.5 C, superior rate capability of 133.1 mAh g−1MAI at 50 C, and ultrahigh capacity retention rate of 98.3% over 10000 cycles (5 months). In‐situ, ex‐situ spectral characterizations and density functional theory calculations clarify the robust chemical interaction between iodides and organic groups. The cathode chemistries elucidated here propel the development of Li–I2 batteries and are expected to be extended to other metal‐iodine battery technology.

Triazine-based porous organic polymers for reversible capture of iodine and utilization in antibacterial application

Abstract: The capture and safe storage of radioactive iodine (129I or 131I) are of a compelling significance in the generation of nuclear energy and waste storage. Because of their physiochemical properties, Porous Organic Polymers (POPs) are considered to be one of the most sought classes of materials for iodine capture and storage. Herein, we report on the preparation and characterization of two triazine-based, nitrogen-rich, porous organic polymers, NRPOP-1 (SABET = 519 m2 g-1) and NRPOP-2 (SABET = 456 m2 g-1), by reacting 1,3,5-triazine-2,4,6-triamine or 1,4-bis-(2,4-diamino-1,3,5-triazine)-benzene with thieno[2,3-b]thiophene-2,5-dicarboxaldehyde, respectively, and their use in the capture of volatile iodine. NRPOP-1 and NRPOP-2 showed a high adsorption capacity of iodine vapor with an uptake of up to 317 wt % at 80 °C and 1 bar and adequate recyclability. The NRPOPs were also capable of removing up to 87% of iodine from 300 mg L-1 iodine-cyclohexane solution. Furthermore, the iodine-loaded polymers, I2@NRPOP-1 and I2@NRPOP-2, displayed good antibacterial activity against Micrococcus luteus (ML), Escherichia coli (EC), and Pseudomonas aeruginosa (PSA). The synergic functionality of these novel polymers makes them promising materials to the environment and public health.

Formation of twelve-fold iodine coordination at high pressure

Abstract: Abstract Halogen compounds have been studied widely due to their unique hypercoordinated and hypervalent features. Generally, in halogen compounds, the maximal coordination number of halogens is smaller than eight. Here, based on the particle swarm optimization method and first-principles calculations, we report an exotically icosahedral cage-like hypercoordinated IN 6 compound composed of N 6 rings and an unusual iodine−nitrogen covalent bond network. To the best of our knowledge, this is the first halogen compound showing twelve-fold coordination of halogen. High pressure and the presence of N 6 rings reduce the energy level of the 5d orbitals of iodine, making them part of the valence orbital. Highly symmetrical covalent bonding networks contribute to the formation of twelve-fold iodine hypercoordination. Moreover, our theoretical analysis suggests that a halogen element with a lower atomic number has a weaker propensity for valence expansion in halogen nitrides.

Impact of photon-counting-detector-CT derived virtual-monoenergetic-images and iodine-maps on the diagnosis of pleural empyema.

Abstract: The purpose of this study was to evaluate the impact of virtual monoenergetic image (VMI) energies and iodine maps on the diagnosis of pleural empyema with photon counting detector computed tomography (PCD-CT).In this IRB-approved retrospective study, consecutive patients with non-infectious pleural effusion or histopathology-proven empyema were included. PCD-CT examinations were performed on a dual-source PCD-CT in the multi-energy (QuantumPlus) mode at 120 kV with weight-adjusted intravenous contrast-agent. VMIs from 40-70 keV obtained in 10 keV intervals and an iodine map was reconstructed for each scan. CT attenuation was measured in the aorta, the pleura and the peripleural fat (between autochthonous dorsal muscles and dorsal ribs). Contrast-to-noise (CNR) and signal-to-noise (SNR) ratios were calculated. Two blinded radiologists evaluated if empyema was present (yes/no), and rated diagnostic confidence (1 to 4; not confident to fully confident, respectively) with and without using the iodine map. Sensitivity, specificity and diagnostic confidence were estimated. Interobserver agreement was estimated using an unweighted Cohen kappa test. A one-way ANOVA was used to compare variables. Differences in sensitivity and specificity between the different levels of energy were searched using McNemar test.Sixty patients (median age, 60 years; 26 women) were included. A strong negative correlation was found between image noise and VMI energies (r = -0.98; P = 0.001) and CNR increased with lower VMI energies (r = -0.98; P = 0.002). Diagnostic accuracy (96%; 95% CI: 82-100) as well as diagnostic confidence (3.4 ± 0.75 [SD]) were highest at 40 keV. Diagnostic accuracy and confidence at higher VMI energies improved with the addition of iodine maps (P ≤0.001). Overall, no difference in CT attenuation of peripleural fat between patients with empyema and those with pleural effusion was found (P = 0.07).Low VMI energies lead to a higher diagnostic accuracy and diagnostic confidence in the diagnosis of pleural empyema. Iodine maps help in diagnosing empyema only at high VMI energies.