Commemorating Two Centuries of Iodine Research: An Interdisciplinary Overview of Current Research

Impact of Structural Functionalization, Pore Size, and Presence of Extra-Framework Ions on the Capture of Gaseous I2 by MOF Materials

A computational approach is used on MOF materials to predict the structures showing the best performances for I2 adsorption as a function of the functionalization, the pore size, the presence of the compensating ions, and the flexibility on which to base future improvements in selected materials in view of their targeted application. Such an approach can be generalized for the adsorption of other gases or vapors. Following the results from the simulations, it was evidenced that the maximum capacity of I2 adsorption by MOF solids with longer organic moieties and larger pores could exceed that of previously tested materials. In particular, the best retention performance was evidenced for MIL-100-BTB. However, if the capacity to retain traces of gaseous I2 on the surface is considered, MIL-101-2CH3, MIL-101-2CF3, and UiO-66-2CH3 appear more promising. Furthermore, the impact of temperature is also investigated.

Multifunctional Zn-Ln (Ln = Eu and Tb) heterometallic metal-organic frameworks with highly efficient I2 capture, dye adsorption, luminescence sensing and white-light emission

A new family of isostructural 3d-4f heterometallic metal-organic frameworks (HMOFs), [Zn₃Eu_xTb_2-x(TZI)₄(DMA)₅(H₂O)₃]·4DMA [x = 0 (1), 0.3 (2), 0.6 (3), 0.9 (4), 1 (5), 1.2 (6), 1.5 (7), 1.8 (8), 2 (9)], has been synthesized using the 5-(4-(tetrazol-5-yl) phenyl)isophthalic acid (H₃TZI) ligand, Ln^III ions and Zn^II ions under solvothermal conditions. All HMOFs exhibit a (3,3,4,5,5)-connected 6³·6³(4²·6²·8²)(4·6⁵·8)(4·6⁶·8³) topology, which features three different types of motifs: one is a mononuclear Zn^II ion and the other two motifs are binuclear [Zn(COO)₃Ln] clusters. The adsorption experiments indicate that Zn₃Tb₂ (1) could efficiently remove almost all I₂ from cyclohexane solution after 12 h and also showed better adsorption towards neutral red (NR) dye (adsorption: only the Zn₃Tb₂ (1) was taken as one representative). Simultaneously, the luminescence sensing showed that Zn₃Tb₂ (1) and Zn₃Eu₂ (9) have excellent response and sensitivity towards pollutants such as Fe³⁺ ions and 2,4,6-trinitrophenol (TNP) with high selectivity and a fairly low limit of detection through luminescence quenching effect. Moreover, seven trimetallic-doped HMOFs 2-8 analogues of Zn₃Ln₂ (single) HMOFs were designed and prepared, showing different changes of luminescent color. More interestingly, Zn₃Eu_1.5Tb_0.5 (7) with white-light emission was fabricated by doping relative concentrations of Eu³⁺ and Tb³⁺ ions. To the best of our knowledge, Zn₃Eu_1.5Tb_0.5 (7) represents a novel kind of heterometallic Zn₃Ln₂ HMOFs with white-light emission. It could be deduced that the excellent characteristics, namely strong typical luminescence emission of Zn^II and Ln^III ions, microporous channels, active open metal sites (tetra-coordinated Zn^II-metal sites), and uncoordinated carboxylate O atoms and uncoordinated tetrazolate N atoms, made the above HMOFs an ideal platform for adsorption, luminescence sensing, and white-light emission. More significantly, these HMOFs are the first reported Zn-Ln heterometallic materials with the H₃TZI ligand.

Functionalized Ionic Porous Organic Polymers Exhibiting High Iodine Uptake from Both the Vapor and Aqueous Medium

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.

Remote Substituents as Potential Control Elements for the Solid-State Structures of Hypervalent Iodine(III) Compounds

Hypervalent iodine (HVI) compounds are very important selective oxidants often employed in organic syntheses. Most HVI compounds are strongly associated in the solid state involving interactions between the electropositive iodine centers and nearby electron lone pairs of electronegative atoms. This study examines the impact of remote substituents on select families of HVI compounds as means to achieve predictable two-dimensional extended solid-state materials. Crystallographic analyses of 10 HVI compounds from several related classes of λ³ organoiodine(III) compounds, (diacetoxyiodo)benzenes, (dibenzoatoiodo)benzenes, [bis(trifluoroacetoxy)iodo]benzenes, and μ-oxo-[(carboxylateiodo)benzenes], provide insights into how remote substituents and the choice of carboxylate groups can impact intermolecular interactions in the solid state.

Construction of ionic liquid functionalized MXene with extremely high adsorption capacity towards iodine via the combination of mussel-inspired chemistry and Michael addition reaction

In this work, a highly efficient adsorbent based on ionic liquid functionalized MXene has been fabricated through the combination of mussel-inspired chemistry and Michael addition reaction. The surface of MXene was first coated with polydopamine (PDA) through self-polymerization of dopamine and the amino groups were introduced on the surface of MXene simultaneously. After that, the ene bond-containing ionic liquid was further immobilized on the surface of MXene-PDA to obtain MXene-PDA-IL. As a concept, the adsorptive removal of iodine using MXene-PDA-IL was conducted and the effects of various factors on the adsorption behavior were examined. The experimental data were analyzed by intermittent adsorption experiments, the adsorption kinetics, adsorption isotherm, adsorption thermodynamics, and cyclic adsorption experiments. We found that the adsorption procedure could reach equilibrium within 10 min after mixing adsorbent and iodine. The maximum adsorption capacity of MXene-PDA-IL towards iodine was as high as 695.4 mg g^-1, which is greater than most of reported adsorbents. Considered the advantages of mussel-inspired chemistry for surface functionalization and the adsorption capacity of ionic liquids, the method could be used for construct a number of composites with potential for adsorption applications.

Direct Iodination of Electron-Deficient Benzothiazoles: Rapid Access to Two-Photon Absorbing Fluorophores with Quadrupolar D-π-A-π-D Architecture and Tunable Heteroaromatic Core

Direct iodination of benzothiazoles under strong oxidative/acidic conditions leads to a mixture of iodinated heteroarenes with 1-2 major components, which are easily separable and which structures depend on the I₂ equivalents used. Among the unexpected but dominant products were identified 4,7-diiodobenzothiazoles with a rare substitution pattern for S_EAr reactions of this scaffold. These were employed in the synthesis of 4,7-bis(triarylamine-ethynyl)benzothiazoles - a new class of highly efficient quasi-quadrupolar fluorophores displaying large two-photon absorption cross sections (540-1374 GM) in the near-infrared region.

Electrohalogenation of organic compounds

In this review we target sp, sp² and sp³ carbon fluorination, chlorination, bromination and iodination reactions using electrolysis as a redox medium. Mechanistic insights and substrate reactivity are also discussed.

Freezing-Induced Simultaneous Reduction of Chromate and Production of Molecular Iodine: Mechanism, Kinetics, and Practical Implications

A new method for the concurrent treatment of Cr(VI)-contaminated wastewater and production of the useful I₂ chemical was developed. The method is based on the redox reaction between Cr(VI) and I^- that occurs when an aqueous wastewater solution containing Cr(VI) and I^- is frozen, producing I₂ and allowing for the effective removal of Cr. The redox reaction occurs primarily because of the accumulation of Cr(VI), I^-, and protons in the ice grain boundaries formed during freezing (i.e., the freeze concentration effect). This effect was verified by confocal Raman spectroscopy and the experiments varying I^- concentration and pH. The reduction of Cr(VI) (20 μM) was near complete after freezing at I^- concentrations ≥ 100 μM, pH ≤ 3.0, and temperatures ≤ -10 °C. The freezing method (liquid cooling vs air cooling) had little effect on the final Cr(VI) reduction efficiency but had a significant effect on the Cr(VI) reduction rate. The freezing method was also tested with Cr(VI)-contaminated electroplating wastewater samples, and simultaneous Cr(VI) reduction and I₂ production proceeded rapidly in a frozen solution but was not observed in an aqueous solution. Additionally, other substances in electroplating wastewater did not reduce the rate and final efficiency of Cr(VI) reduction and I₂ production. Therefore, the freezing/Cr(VI)/I^- system can be considered a feasible approach to water-energy nexus technology for simultaneous I₂ production and Cr(VI)-contaminated wastewater treatment.

Identification of key functionalization species in the Cp*Ir(III)-catalyzed-ortho halogenation of benzamides

Cp*Ir(iii) complexes have been shown to be effective for the halogenation of N,N-diisopropylbenzamides with N-halosuccinimide as a suitable halogen source. The optimized conditions for the iodination reaction consist of 0.5 mol% [Cp*IrCl2]2 in 1,2-dichloroethane at 60 °C for 1 h to form a variety of iodinated benzamides in high yields. Increasing the catalyst loading to 6 mol% and the time to 4 h enabled the bromination reaction of the same substrates. Reactivity was not observed for the chlorination of these substrates. A variety of functional groups on the para-position of the benzamide were well tolerated. Kinetic studies showed the reaction dependence is first order in iridium, positive order in benzamide, and zero order in N-iodosuccinimide. A KIE of 2.5 was obtained from an independent H/D kinetic isotope effect study. Computational studies (DFT-BP3PW91) indicate that a CMD mechanism is more likely than an oxidative addition pathway for the C-H bond activation step. The calculated functionalization step involves an Ir(v) species that is the result of oxidative addition of acetate hypoiodite that is generated in situ from N-iodosuccinimide and acetic acid.

Tunable Strategies Involving Flexibility and Angularity of Dual Linkers for a 3D Metal-Organic Framework Capable of Multimedia Iodine Capture

The widespread use of nuclear power poses severe health and environmental risks owing to the nonregulated release and disposal of radioactive wastes in the environment. Among these wastes, the capture and removal of radioactive iodine poses a big challenge. To develop a novel material for capturing molecular iodine, we have strategically synthesized a nitrogen-rich three-dimensional (3D) metal-organic framework (MOF), {[Mn₂(oxdz)₂(tpbn)(H₂O)₂]·2C₂H₅OH}_n (1), utilizing a bent heterocyclic dicarboxylate linker (H₂oxdz: (4,4'-(1,3,4-oxadiazole-2,5-diyl)dibenzoic acid)) and a flexible bis(tridentate) ligand (tpbn: N, N', N″, N‴-tetrakis(2-pyridylmethyl)-1,4-diaminobutane). Based on its single-crystal structure, 1 is an eightfold interpenetrated 3D framework, consisting of a unique 4-connected {Mn₂(tpbn)} subunit, in which the pores line up with the nitrogen atoms of the oxadiazole moiety. This can be considered as a big leap for the development of 3D MOFs using flexible bis(tridentate) ligands. To emphasize the role of the flexible methylene chain length in such ligand in the dimensionality of the resultant framework, the tphn (N, N', N″, N‴-tetrakis(2-pyridylmethyl)-1,6-diaminohexane) ligand with two additional methylene groups provides a one-dimensional (1D) CP {[Mn₂(oxdz)₂(tphn)(H₂O)]·CH₃OH}_n (2). This spacer chain lengthening has a profound effect on the coordination of such ligand with Mn(II), further affecting the binding of oxdz. The inherent polarizable nature of the oxadiazole moiety and the presence of permanent pore of dimensions (19.122 × 19.253 Ų) in 1 have been exploited for the capture/removal of iodine not only from vapor and an organic solution but also from an aqueous media. It exhibits competent 100% reversible sorption of iodine with an uptake capacity of (1.1 ± 0.05) g/g of 1. The uptake value has been corroborated by both gravimetric and titrimetric analyses. The interaction of iodine with 1 has been notably studied with molecular simulations, kinetic models of sorption, field emission scanning electron microscopy (FESEM), and energy-dispersive X-ray spectroscopy (EDX) analysis. Moreover, 1 is highly stable and is recyclable without much loss of sorption capability up to five cycles.

Iodine staining as a useful probe for distinguishing insulin amyloid polymorphs

It is recently suggested that amyloid polymorphism, i.e., structural diversity of amyloid fibrils, has a deep relationship with pathology. However, its prompt recognition is almost halted due to insufficiency of analytical methods for detecting polymorphism of amyloid fibrils sensitively and quickly. Here, we propose that iodine staining, a historically known reaction that was firstly found by Virchow, can be used as a method for distinguishing amyloid polymorphs. When insulin fibrils were prepared and iodine-stained, they exhibited different colors depending on polymorphs. Each of the colors was inherited to daughter fibrils by seeding reactions. The colors were fundamentally represented as a sum of three absorption bands in visible region between 400 and 750 nm, and the bands showed different titration curves against iodine, suggesting that there are three specific iodine binding sites. The analysis of resonance Raman spectra and polarization microscope suggested that several polyiodide ions composed of I₃⁻ and/or I₅⁻ were formed on the grooves or the edges of β-sheets. It was concluded that the polyiodide species and conformations formed are sensitive to surface structure of amyloid fibrils, and the resultant differences in color will be useful for detecting polymorphism in a wide range of diagnostic samples.

The C3-H Bond Functionalization of Quinoxalin-2(1H)-Ones With Hypervalent Iodine(III) Reagents

The modification of quinoxalin-2(1H)-ones via direct C-H bond functionalization has begun to receive widespread attention, due to quinoxalin-2(1H)-one derivatives' various biological activities and pharmaceutical properties. This mini review concentrates on the accomplishments of arylation, trifluoromethylation, alkylation, and alkoxylation of quinoxalin-2(1H)-ones with hypervalent iodine(III) reagents as reaction partners or oxidants. The reaction conditions and mechanisms are compared and discussed in detail.

Density Functional Theory-Based Molecular Modeling: Verification of Decisive Roles of Van der Waals Aggregation of Triiodide Ions for Effective Electron Transfer in Wet-Type N3-Dye-Sensitized Solar Cells

Density functional theory-based molecular modeling (DFT/MM) validates that KI and I2 undergo exothermic van der Waals (vdW) aggregation in acetonitrile (AN) or in the presence of 4-tert-butylpyridine (TBP), forming potassium triiodide (KI3) and, further mutual vdW aggregation leads to the formation of (KI3)2 and AN, (KI3)2 and (AN)2 and (KI3)2 and TBP in the AN-based Dye sensitized solar cells (DSSC) electrolytes. All KI3 aggregates have a very low energy gap, 0.17 eV, 0.14 eV and 0.05 eV of lowest unoccupied molecular orbital (LUMO) + 1 and LUMO, respectively, verifying efficient electron diffusion in μm-thick DSSC electrolytes. Hydrogen-bonding aggregation of anatase TiO2 model, Ti9O18H and OH, with N3 (proton) dye is also validated by DFT/MM, and the energy structure verifies unidirectional electron flow from highest occupied molecular orbital (HOMO) on thiocyanide (SCN) groups of N3 dye to LUMO on the TiO2 model at the aggregates. Further, DFT/MM for the aggregation of K+I3− with N3 verifies the most exothermic formation of the aggregate of N3 (proton) and K+I3−. The UV-Vis spectra of N3 (proton) and K+I3− is consistent with reported incident photocurrent efficiency (IPCE) action spectra (λ = 450–800 nm) of N3-sensitized DSSC, verifying that the N3 dye of N3 (proton) and K+I3− becomes an effective sensitizer in the anode / TiO2 / N3 (proton) / KI/I2 / acetonitrile (AN) / cathode structured DSSC. The energy structure of LUMO and LUMO + 1 of the aggregates, Ti9O18H and OH and N3 (proton), N3 and K+I3−, (KI3)2 and AN and (KI3)2 and TBP verifies high IPCE photocurrent and effective electron diffusion via KI3-aggregates in the DSSC of Ti9O18H and OH and N3 (proton) and K+I3−.

Theoretical Modeling of Electronic Structures of Polyiodide Species Included in α-Cyclodextrin

The molecular mechanism of blue color formation in an iodine-starch reaction is studied by employing the iodine-α-cyclodextrin (α-CD) complex as a practical model system that resembles the structural properties of the blue amylose-iodine complex. To this end, we construct, using the quantum chemistry method, a molecular model of the complex (I₅^-/Li⁺/2α-CD) that consists of one I₅^-, two molecules of α-CD, and a lithium cation, and this model is employed as a basic unit in constructing the structural models of polyiodide ions (I₅^-)_n. The initial structure in the geometry optimization is adopted from the α-CD-iodine complex structure obtained from the X-ray crystallography study. The structural models of (I₅^-)_n are built by adding the basic unit n times along the crystal axis and by optimizing the structure using quantum mechanics/molecular mechanics (QM (iodine)/MM (α-CD)) calculations. The electronic absorption spectra of the resulting model structures are calculated by time-dependent density functional theory (TD-DFT). We find that I₅^- acts as a basic unit of coloration in the visible region. The visible color originates from the electronic transition within the I₅^- molecule, and any charge transfer between the I₅^- ion and either of α-CD or a coexisting counter cation is not involved. We also reveal that the electronic transitions of (I₅^-)_n are delocalized, which accounts for the well-known observation that the color of the iodine-starch reaction becomes bluish with an increase in the chain length of amylose. Furthermore, the preresonance Raman spectra calculated from the model suggest that the vibrational motions are localized in the I₅^- subunit dominantly. A comparison between an experimental absorption spectrum feature of the α-CD-iodine complex and the calculated ones of (I₅^-)_n ions with various n values suggests that (I₅^-)₄ polyiodide ions tend to be populated dominantly in the α-CD-iodine complex under aqueous conditions.

Supramolecular-Macrocycle-Based Crystalline Organic Materials

Supramolecular macrocycles are well known as guest receptors in supramolecular chemistry, especially host-guest chemistry. In addition to their wide applications in host-guest chemistry and related areas, macrocycles have also been employed to construct crystalline organic materials (COMs) owing to their particular structures that combine both rigidity and adaptivity. There are two main types of supramolecular-macrocycle-based COMs: those constructed from macrocycles themselves and those prepared from macrocycles with other organic linkers. This review summarizes recent developments in supramolecular-macrocycle-based COMs, which are categorized by various types of macrocycles, including cyclodextrins, calixarenes, resorcinarenes, pyrogalloarenes, cucurbiturils, pillararenes, and others. Effort is made to focus on the structures of supramolecular-macrocycle-based COMs and their structure-function relationships. In addition, the application of supramolecular-macrocycle-based COMs in gas storage or separation, molecular separation, solid-state electrolytes, proton conduction, iodine capture, water or environmental treatment, etc., are also presented. Finally, perspectives and future challenges in the field of supramolecular-macrocycle-based COMs are discussed.

Census of halide-binding sites in protein structures

Motivation

Halides are negatively charged ions of halogens, forming fluorides (F⁻), chlorides (Cl⁻), bromides (Br⁻) and iodides (I⁻). These anions are quite reactive and interact both specifically and non-specifically with proteins. Despite their ubiquitous presence and important roles in protein function, little is known about the preferences of halides binding to proteins. To address this problem, we performed the analysis of halide–protein interactions, based on the entries in the Protein Data Bank.

Results

We have compiled a pipeline for the quick analysis of halide-binding sites in proteins using the available software. Our analysis revealed that all of halides are strongly attracted by the guanidinium moiety of arginine side chains, however, there are also certain preferences among halides for other partners. Furthermore, there is a certain preference for coordination numbers in the binding sites, with a correlation between coordination numbers and amino acid composition. This pipeline can be used as a tool for the analysis of specific halide–protein interactions and assist phasing experiments relying on halides as anomalous scatters.

Availability and implementation

All data described in this article can be reproduced via complied pipeline published at https://github.com/rostkick/Halide_sites/blob/master/README.md.

Supplementary information

Supplementary data are available at Bioinformatics online.

Unexpected structural complexity of thorium coordination polymers and polyoxo cluster built from simple formate ligands

A simple synthetic approach with [HCOOH]/[Th(iv)] and water controls the yield of six thorium formates with unexpected structural complexity.

Iodine-Catalyzed Regioselective Oxidative Cyclization of Aldehyde Hydrazones with Electron-Deficient Olefins for the Synthesis of Mefenpyr-Diethyl

A regioselective synthesis of polysubstituted dihydropyrazoles and pyrazoles through an iodine-catalyzed oxidative cyclization strategy of aldehyde hydrazones with electron-deficient olefins is described. The protocol adopts very mild reaction conditions and provides desirable yields. The reaction is supposed to proceed via a cascade C-H functionalization, C-N bond formation, and oxidation sequential processes. The overall simplicity and regioselectivity of the catalytic system make this approach a valuable and step-economical tool to construct a C-C bond for the synthesis of Mefenpyr-Diethyl.

One-Step Synthesis of Furan Rings from α-Isopropylidene Ketones Mediated by Iodine/DMSO: An Approach to Potent Bioactive Terpenes

The system I₂/dimethyl sulfoxide mediates the one-step transformation of α-isopropylidene ketones into furan rings following a biomimetic approach. This methodology has been used for the synthesis of terpene furans such as mintfurane, curzerene, atractylon, and isoatractylon, all of them possessing interesting biological activities. The synthesis of linderazulene directly from 4,5-epoxygermacrone via a cascade reaction shows the potential of this protocol. Additionally, this compound proved to show significant ixodicidal activity.

Key aspects of the iodine metabolism in brown algae: a brief critical review

Brown algae include the strongest accumulators of iodine known among living systems. This paper reviews the current state of bioinorganic research in the field, focusing on the models Laminaria digitata, Macrocystis pyrifera and Ectocarpus siliculosus, and covering uptake and efflux, localization and biological significance of storage, as well as marine and atmospheric chemistry of iodine.

Lithium-triggered spontaneous formation of polyiodides in room-temperature ionic liquid-alcohol solutions

In this study, the effect of alcohol on polyiodide formation in room-temperature ionic liquid (RTIL) was examined by time evolutions of Raman spectra in the low-frequency region and by color changes of the sample. The RTIL was 1-methyl-3-propylimidazolium iodide, [C₃mim][I]. Polyiodides develop in [C₃mim][I]‑lithium salt-ethanol solutions (Abe et al., Chem. Phys. 502 (2018) 72.). Without the external addition of iodine or without an external electric field, the irreversible transformation from I^- to I₃^- indicates that charge unbalancing was promoted by lithium ion. Polyiodide formations were not induced by sodium or potassium ions. Strong alcohol effects were observed directly by the time-dependent Raman bands in the low-frequency region.

Optimization of Phlorotannins Extraction from Fucus vesiculosus and Evaluation of Their Potential to Prevent Metabolic Disorders

Phlorotannins are phloroglucinol-based phenolic compounds, occurring particularly in brown macroalgae, that have been recognized for their promising bioactive properties. In this study, the extraction of phlorotannins from Fucus vesiculosus was evaluated with particular emphasis on the influential parameters, including the solvent concentration, solvent-solid ratio, extraction temperature and extraction time, using a single-factor design followed by a Box-Behnken design. The maximum total phlorotannin content, determined using the 2,4-dimethoxybenzaldehyde (DMBA) method, corresponded to 2.92 ± 0.05 mg of phloroglucinol equivalents/g dry seaweed (mg PGE/g DS), and was achieved for extracts carried out with acetone 67% (v/v), a solvent-solid ratio of 70 mL/g and temperature at 25 °C. This crude extract, together with a semi-purified phlorotannin fraction, were further evaluated for their anti-enzymatic capacity against α-glucosidase, α-amylase and pancreatic lipase, both showing promising inhibitory effects, particularly against α-glucosidase for which a greater inhibitory effect was observed compared to the pharmaceutical drug acarbose (IC50 = 4.5 ± 0.8 and 0.82 ± 0.3 μg/mL, respectively, against 206.6 ± 25.1 μg/mL). Additionally, the ultra-high-pressure liquid chromatography coupled to mass spectrometry (UHPLC-MS) analysis carried out on the ethyl acetate fraction revealed the presence of fucols, fucophlorethols, fuhalols and several other phlorotannin derivatives. Moreover, possible new phlorotannin compounds, including fucofurodiphlorethol, fucofurotriphlorethol and fucofuropentaphlorethol, have been tentatively identified in this extract. Overall, this study provides evidence that F. vesiculosus phlorotannin-rich extracts hold potential for the management of the activity of α-glucosidase, α-amylase and pancreatic lipase, which are well known to be linked to metabolic disorders such as diabetes and obesity.

Emission of volatile halogenated compounds, speciation and localization of bromine and iodine in the brown algal genome model Ectocarpus siliculosus

This study explores key features of bromine and iodine metabolism in the filamentous brown alga and genomics model Ectocarpus siliculosus. Both elements are accumulated in Ectocarpus, albeit at much lower concentration factors (2-3 orders of magnitude for iodine, and < 1 order of magnitude for bromine) than e.g. in the kelp Laminaria digitata. Iodide competitively reduces the accumulation of bromide. Both iodide and bromide are accumulated in the cell wall (apoplast) of Ectocarpus, with minor amounts of bromine also detectable in the cytosol. Ectocarpus emits a range of volatile halogenated compounds, the most prominent of which by far is methyl iodide. Interestingly, biosynthesis of this compound cannot be accounted for by vanadium haloperoxidase since the latter have not been found to catalyze direct halogenation of an unactivated methyl group or hydrocarbon so a methyl halide transferase-type production mechanism is proposed.

Nonporous Adaptive Crystals of Pillararenes

Porous materials with high surface areas have drawn more and more attention in recent years because of their wide applications in physical adsorption and energy-efficient adsorptive separation processes. Most of the reported porous materials are macromolecular porous materials, such as zeolites, metal-organic frameworks (MOFs), or porous coordination polymers (PCPs), and porous organic polymers (POPs) or covalent organic frameworks (COFs), in which the building blocks are linked together by covalent or coordinative bonds. These materials are barely soluble and thus are not solution-processable. Furthermore, the relatively low chemical, moisture, and thermal stability of most MOFs and COFs cannot be neglected. On the other hand, molecular porous materials such as porous organic cages (POCs), which have been developed very recently, also show promising applications in adsorption and separation processes. They can be soluble in organic solvents, making them solution-processable materials. However, they are usually sensitive to acid/base and humid environments since most of them are based on dynamic covalent bonding. These macromolecular and molecular porous materials usually have two similar features: high Brunauer-Emmett-Teller (BET) surface areas and rigid pore structures, which are stable during adsorption and separation processes. In this Account, we describe a novel class of solid materials for adsorption and separation, nonporous adaptive crystals (NACs), which function at the supramolecular level. They are nonporous in the initial crystalline state, but the intrinsic or extrinsic porosity of the crystals along with a crystal structure transformation is induced by preferable guest molecules. Unlike solvent-induced crystal polymorphism phenomena of common organic crystals that occur at the solid-liquid phase, NACs capture vaporized guests at the solid-gas phase. Upon removal of guest molecules, the crystal structure transforms back to the original nonporous structure. Here we focus on the discussion of pillararene-based NACs for adsorption and separation and the crystal structure transformations from the initial nonporous crystalline state to new guest-loaded structures during the adsorption and separation processes. Single-crystal X-ray diffraction, powder X-ray diffraction, gas chromatography, and solution NMR spectroscopy are the main techniques to verify the adsorption and separation processes and the structural transformations. Compared with traditional porous materials, NACs of pillararenes have several advantages. First, their preparation is simple and cheap, and they can be synthesized on a large scale to meet practical demands. Second, pillararenes have better chemical, moisture, and thermal stability than crystalline MOFs, COFs, and POCs, which are usually constructed on the basis of reversible chemical bonds. Third, pillararenes are soluble in many common organic solvents, which means that they can be easily processed in solution. Fourth, their regeneration is simple and they can be reused many times with no decrease in performance. It is expected that this class of materials will not only exert a significant influence on scientific research but also show practical applications in chemical industry.

Highly practical and efficient preparation of aldehydes and ketones from aerobic oxidation of alcohols with an inorganic-ligand supported iodine catalyst

Herein, we divulge an efficient protocol for aerobic oxidation of alcohols with an inorganic-ligand supported iodine catalyst, (NH4)5[IMo6O24]. The catalyst system is compatible with a wide range of groups and exhibits high selectivity, and shows excellent stability and reusability, thus serving as a potentially greener alternative to the classical transformations.

Phycochemical Constituents and Biological Activities of Fucus spp

Seaweeds are known to be a good supply of key nutrients including carbohydrates, protein, minerals, polyunsaturated lipids, as well as several other health-promoting compounds capable of acting on a wide spectrum of disorders and/or diseases. While these marine macroalgae are deeply rooted in the East Asian culture and dietary habits, their major application in Western countries has been in the phycocolloid industry. This scenario has however been gradually changing, since seaweed consumption is becoming more common worldwide. Among the numerous edible seaweeds, members of the genus Fucus have a high nutritional value and are considered good sources of dietary fibers and minerals, especially iodine. Additionally, their wealth of bioactive compounds such as fucoidan, phlorotannins, fucoxanthin and others make them strong candidates for multiple therapeutic applications (e.g., antioxidant, anti-inflammatory, anti-tumor, anti-obesity, anti-coagulant, anti-diabetes and others). This review presents an overview of the nutritional and phytochemical composition of Fucus spp., and their claimed biological activities, as well as the beneficial effects associated to their consumption. Furthermore, the use of Fucus seaweeds and/or their components as functional ingredients for formulation of novel and enhanced foods is also discussed.

Recent advances in hypervalent iodine(III)-catalyzed functionalization of alkenes

Hypervalent iodine(III) reagents have been well-developed and widely utilized in functionalization of alkenes, however, generally either stoichiometric amounts of iodine(III) reagents are required or stoichiometric oxidants such as mCPBA are employed to in situ generate iodine(III) species. In this review, recent developments of hypervalent iodine(III)-catalyzed functionalization of alkenes and asymmetric reactions using a chiral iodoarene are summarized.

Amorphous Porous Organic Polymers Based on Schiff-Base Chemistry for Highly Efficient Iodine Capture

Porous organic polymers (POPs) have been considered as prominent adsorbents for volatile iodine. So far, both crystalline and amorphous POPs have accomplished excellent iodine capture capability. Considering the difficulty and challenges in preparing perfect crystalline POPs, more explorations into developing versatile amorphous POPs are needed. Herein, amorphous POPs based on the Schiff-base reaction were designed and synthesized for volatile iodine removal. Four amorphous POPs products named as NDB-H, NDB-S, ADB-HS, and ADB-S obtained under different solvothermal conditions were investigated in terms of their morphologies, porosity, and their iodine enrichment performance in detail. It is noteworthy that excellent efficiency for removing iodine vapor was acquired for NDB-S (≈425 wt %), ADB-HS (≈345 wt %), and ADB-S (≈342 wt %). Remarkably, NDB-H exhibited an iodine capture capacity up to ≈443 wt %. Excellent reusability was obtained as well. Amorphous NDB-H has accomplished an extremely high iodine capture performance, illustrating the great chance to exploit versatile amorphous POPs for iodine enrichment and removal based on Schiff-base chemistry.

I2-Catalyzed Oxidative Cross-Coupling Reaction of Methyl Ketones and 2-(2-Aminophenyl) Benzimidazole: Facile Access to Benzimidazo[1,2-c]quinazoline

A general and efficient iodine-catalyzed metal-free oxidative cross-coupling reaction of methyl ketones with 2-(1H-benzo[d]imidazol-2-yl)aniline has been established. This is a new synthetic strategy for the synthesis of benzimidazo[1,2-c]quinazoline derivatives involving C(sp³)-H oxidation, condensation, and cyclization processes.

A survey of chiral hypervalent iodine reagents in asymmetric synthesis

The recent years have witnessed a remarkable growth in the area of chiral hypervalent iodine chemistry. These environmentally friendly, mild and economic reagents have been used in catalytic or stoichiometric amounts as an alternative to transition metals for delivering enantioenriched molecules. Varieties of different chiral reagents and their use for demanding asymmetric transformations have been documented over the last 25 years. This review highlights the contribution of different chiral hypervalent iodine reagents in diverse asymmetric conversions.

Zeolite-like Metal-Organic Framework (MOF) Encaged Pt(II)-Porphyrin for Anion-Selective Sensing

The selectivity and sensitivity of sensors are of great interest to the materials chemistry community, and a lot of effort is now devoted to improving these characteristics. More specifically, the selective sensing of anions is one of the largest challenges impeding the sensing-research area due to their similar physical and chemical behaviors. In this work, platinum-metalated porphyrin (Pt(II)TMPyP) was successfully encapsulated in a rho-type zeolite-like metal-organic framework (rho-ZMOF) and applied for anion-selective sensing. The sensing activity and selectivity of the MOF-encaged Pt(II)TMPyP for various anions in aqueous and methanolic media were compared to that of the free (nonencapsulated) Pt(II)TMPyP. While the photoinduced triplet-state electron transfer of Pt(II)TMPyP showed a very low detection limit for anions with no selectivity, the Pt(II)TMPyP encapsulated in the rho-ZMOF framework possessed a unique chemical structure to overcome such limitations. This new approach has the potential for use in other complex sensing applications, including biosensors, which require ion selectivity.

Low-temperature and high-pressure phases of a room-temperature ionic liquid and polyiodides: 1-methyl-3-propylimidazolium iodide

Experimental results are summarized on the P–T–m diagram. In pure [C₃mim][I], amorphous phase appeared both at low-temperature and high-pressure. Stoichiometric [C₃mim][I₃] promotes crystallization, while non-stoichiometric [C₃mim][I_3.66] indicates anomalies.

A convenient one-pot synthesis of N-substituted amidoximes and their application toward 1,2,4-oxadiazol-5-ones

The first direct one-pot approach for the synthesis of N-substituted amidoximes from secondary amides or the intermediate amides has been developed. Through the Ph₃P–I₂-mediated dehydrative condensation, a variety of N-aryl and N-alkyl amidoximes (R¹(C Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> NOH)NHR², where R¹ or R² = aryl, alkyl, or benzyl) were readily afforded under mild conditions and short reaction times. The synthetic application of the obtained amidoximes has also been demonstrated through the formation of 1,2,4-oxadiazolones via base-mediated carbonylative cyclization with 1,1′-carbonyldiimidazole.

Ph₃P–I₂ mediated one-pot synthesis of N-substituted amidoximes via imidoyl iodide was developed. The synthesis of 1,2,4-oxadiazol-5-ones was also demonstrated.

A weaker donor shows higher oxidation state upon aggregation

The charge-transfer between TTFs and I₂ shows that the stronger donor TTF1 is in a cation radical state and the weaker donor TTF2 is neutral in solution, whereas TTF1 exists as a cation radical and TTF2 is dicationic in complexes. The dicationic and neutral states of TTF2 are reversible upon aggregation and solvation.

A weaker donor is dicationic but a stronger donor appears as a cation radical in their CT complexes with iodine.

Iodine-mediated cross-dehydrogenative coupling of pyrazolones and alkenes

An iodine-mediated alkenylation of pyrazolones with simple alkenes under air has been developed, leading directly to alkenylated pyrazolone derivatives in good yield.