Room-temperature synthesized In-BiOBr1-xIx nanosheets with visible-light-driven superior photocatalytic activity: Degradation of dye/non-dye organic pollutants for environmental remediation

Photocatalysis is extensively investigated as a green, efficient and promising technique for environmental remediation. In this study, a series of template free In-doped BiOBr_xI_1-x photocatalysts have been successfully prepared at room temperature and characterized by various methods. Complete degradation of negatively charged methyl Orange, positively charged Rhodamine B and Methylene Blue organic dyes, and neutral and colorless non-dye organic compound of furfural was attained. The flat band potential offered the possibility of reduction of dissolved O₂ to O₂^.- in the conduction band while the trapping experiment identified the (O₂^.-)is the main radical species followed by h⁺ for the photodegradation. In-BiOBrI-0.4 had an excellent photocatalytic degradation activity which could be due to the synergetic effect between metal ion doping and solid solution formation. It further promotes visible light-harvesting ability and photoinduced charge carrier separation efficiency. The order of the reaction rate was determined and the mechanism was proposed. This work can lay a base for the design of effective photocatalyst toward environmental remediation.

Dearomatization of Electron-Deficient Phenols to ortho-Quinones: Bidentate Nitrogen-Ligated Iodine(V) Reagents

Despite their broad utility, the synthesis of ortho-quinones remains a significant challenge, in particular, access to electron-deficient derivatives remains an unsolved problem. Reported here is the first general method for the synthesis of electron-deficient ortho-quinones by direct oxidation of phenols. The reaction is enabled by a novel bidentate nitrogen-ligated iodine(V) reagent, a previously unexplored class of compounds which we have termed Bi(N)-HVIs. The reaction is extremely general and proceeds with excellent regioselectivity for the ortho over para isomer. Functionalization of the ortho-quinone products was examined, resulting in a facile one-pot synthesis of catechols, as well as the incorporation of a variety of heteroatom nucleophiles. This method represents the first synthetic application of Bi(N)-HVIs and demonstrates their potential as a platform for the further development of highly reactive, but also highly tunable, I(V) reagents.

Reaction kinetics of corrinoid-mediated deiodination of iodinated X-ray contrast media and other iodinated organic compounds

Iodinated contrast media (ICM) are found at considerably higher concentrations than any other pharmaceutical in waste water, surface water and bank filtrate. While the compounds are persistent to deiodination in aerobic environments, field data from bank filtration transects have demonstrated a partial deiodination in reducing soil-water environments. In a previous lab study, we have shown that this reductive deiodination is abiotically catalyzed by (free) corrinoids. To achieve a better understanding of the incomplete deiodination in the environment, we now investigated the reaction kinetics based on the decrease of the iodinated compound, the formation of deiodinated transformation products and the iodide release. The deiodination follows first-order kinetics and consists of three partial reactions for the release of three iodine atoms. The deiodination rate decreased with decreasing iodination degree with the deiodination rate constants k₁ > k₂ > k₃. In contrast to the ICM, 2,4,6- and 2,3,5-triiodobenzoic acid, 5-amino-2,4,6-triiodoisophthalic acid and monoiodobenzoic acids did not show a complete deiodination under the same test conditions. Our results show that the deiodination strongly depends on the substitution pattern of the bound iodine atoms as well as on adjacent functional groups. Iodine atoms in ortho-position to another iodine atom or a carboxyl group were released more easily while an amino group in ortho-position inhibited the deiodination. Tests in tap water in the presence of B₁₂ showed a much slower deiodination than in ultrapure water, most likely caused by competitive electron acceptors in the water matrix.

Implications of Chemical Reduction Using Hydriodic Acid on the Antimicrobial Properties of Graphene Oxide and Reduced Graphene Oxide Membranes

The antimicrobial properties of graphene-based membranes such as single-layer graphene oxide (GO) and modified graphene oxide (rGO) on top of cellulose ester membrane are reported in this study. rGO membranes are made from GO by hydriodic acid (HI) vapor treatment. The antibacterial properties are tested after 3 h contact time with selected model bacteria. Complete bacterial cell inactivation is found only after contact with rGO membranes, while no significant bacterial inactivation is found for the control i) GO membrane, ii) the mixed cellulose ester support, and the iii) rGO membrane after additional washing that removes the remaining HI. This indicates that the antimicrobial effect is neither caused by the graphene nor the membrane support. The antimicrobial effect is found to be conclusively linked to the HI eliminating microbial growth, at concentrations from 0.005%. These findings emphasize the importance of caution in the reporting of antimicrobial properties of graphene-based surfaces.

Rapid oxidation of iodide and hypoiodous acid with ferrate and no formation of iodoform and monoiodoacetic acid in the ferrate/I-/HA system

Toxic and odorous iodinated disinfection byproducts (I-DBPs) could form in the chemical oxidation of iodine-containing water. A critical step for controlling the hazardous I-DBPs is to convert the iodine species into stable and harmless iodate (IO₃^-) while inhibiting the accumulation of highly reactive hypoiodous acid (HOI). Herein, the oxidation of I^- and HOI with ferrate was investigated, and the formation profile of HOI was determined based on 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) coloring method through a stopped-flow spectrophotometer. The second-order rate constants (k_app) of ferrate with HOI decreased from 1.6 × 10⁵ M^-1s^-1 to 8.3 × 10² M^-1s^-1 as the solution pH varied from 5.3 to 10.3, which were 7.5, 7.2 and 13.8 times higher than that of ferrate with I^- at pH 6.0, 7.0 and 8.0, respectively. Compared with other oxidants such as ozone, hypochlorous acid, chloramine and potassium permanganate, ferrate would swiftly oxidize HOI formed in the I^- oxidation process. For the ferrate oxidation of I-containing water, HOI was swiftly oxidized to IO₃^- from pH 5.0 to 9.0. Phosphate buffer promoted the oxidation of I^- while inhibited the oxidation of HOI with ferrate. When 5 mgC/L of humic acids (HA) existed in the solution, no formation of iodoform and monoiodoacetic acid (MIAA) was observed in the oxidation of iodide (20 μM) with ferrate (from 10 μM to 80 μM). These results suggested that ferrate oxidation could be an effective method for the control of I-DBPs in iodine-containing water treatment.

Susceptibility of influenza viruses to hypothiocyanite and hypoiodite produced by lactoperoxidase in a cell-free system

Lactoperoxidase (LPO) is an enzyme found in several exocrine secretions including the airway surface liquid producing antimicrobial substances from mainly halide and pseudohalide substrates. Although the innate immune function of LPO has been documented against several microbes, a detailed characterization of its mechanism of action against influenza viruses is still missing. Our aim was to study the antiviral effect and substrate specificity of LPO to inactivate influenza viruses using a cell-free experimental system. Inactivation of different influenza virus strains was measured in vitro system containing LPO, its substrates, thiocyanate (SCN^-) or iodide (I^-), and the hydrogen peroxide (H₂O₂)-producing system, glucose and glucose oxidase (GO). Physiologically relevant concentrations of the components of the LPO/H₂O₂/(SCN^-/I^-) antimicrobial system were exposed to twelve different strains of influenza A and B viruses in vitro and viral inactivation was assessed by determining plaque-forming units of non-inactivated viruses using Madin-Darby canine kidney cells (MDCK) cells. Our data show that LPO is capable of inactivating all influenza virus strains tested: H1N1, H1N2 and H3N2 influenza A viruses (IAV) and influenza B viruses (IBV) of both, Yamagata and Victoria lineages. The extent of viral inactivation, however, varied among the strains and was in part dependent on the LPO substrate. Inactivation of H1N1 and H1N2 viruses by LPO showed no substrate preference, whereas H3N2 influenza strains were inactivated significantly more efficiently when iodide, not thiocyanate, was the LPO substrate. Although LPO-mediated inactivation of the influenza B strains tested was strain-dependent, it showed slight preference towards thiocyanate as the substrate. The results presented here show that the LPO/H₂O₂/(SCN^-/I^-) cell-free, in vitro experimental system is a functional tool to study the specificity, efficiency and the molecular mechanism of action of influenza inactivation by LPO. These studies tested the hypothesis that influenza strains are all susceptible to the LPO-based antiviral system but exhibit differences in their substrate specificities. We propose that a LPO-based antiviral system is an important contributor to anti-influenza virus defense of the airways.

Transformation of Methylparaben by aqueous permanganate in the presence of iodide: Kinetics, modeling, and formation of iodinated aromatic products

This work investigated impacts of iodide (I^-) on the transformation of the widely used phenolic preservative methylparaben (MeP) as well as 11 other phenolic compounds by potassium permanganate (KMnO₄). It was found that KMnO₄ showed a low reactivity towards MeP in the absence of I^- with apparent second-order rate constants (k_app) ranging from 0.065 ± 0.0071 to 1.0 ± 0.1 M^-1s^-1 over the pH range of 5-9. The presence of I^- remarkably enhanced the transformation rates of MeP by KMnO₄ via the contribution of hypoiodous acid (HOI) in situ formed, which displayed several orders of magnitude higher reactivity towards MeP than KMnO₄. This enhancing effect of I^- was greatly influenced by solution conditions (e.g., I^- or KMnO₄ concentration or pH), which could be well simulated by a kinetic model involving competition reactions (i.e., KMnO₄ with I^-, KMnO₄ with MeP, HOI with KMnO₄, and HOI with MeP). Similar enhancing effect of I^- on the transformation kinetics of 5 other selected phenols (i.e., p-hydroxybenzoic acid, phenol, and bromophenols) at pH 7 was also observed, but not in the cases of bisphenol A, triclosan, 4-n-nonylphenol, and cresols. This discrepancy could be well explained by the relative reactivity of KMnO₄ towards phenols vs I^-. Liquid chromatography-tandem mass spectrometry analysis showed that iodinated aromatic products and/or iodinated quinone-like product were generated in the cases where I^- enhancing effect was observed. Evolution of iodinated aromatic products generated from MeP (10 μM) treated by KMnO₄ (50-150 μM) in the presence of I^- (5-15 μM) suggested that higher I^- or moderate KMnO₄ concentration or neutral pH promoted their formation. A similar enhancing effect of I^- (1 μM) on the transformation of MeP (1 μM) by KMnO₄ (12.6 μM) and formation of iodinated aromatic products were also observed in natural water. This work demonstrates an important role of I^- in the transformation kinetics and product formation of phenolic compounds by KMnO₄, which has great implications for future applications of KMnO₄ in treatment of I^--containing water.

Reactions of hypoiodous acid with model compounds and the formation of iodoform in absence/presence of permanganate

The kinetics for the reactions of hypoiodous acid (HOI) with various phenols (phenol, 4-nitrophenol, 4-hydroxybenzoic acid), 3-oxopentanedioic acid (3-OPA) and flavone were investigated in the pH range of 6.0-11.0. The apparent second order rate constants for the reactions of HOI with phenolic compounds, 3-OPA, flavone and citric acid at pH 8.0 are 10-10⁷ M^-1s^-1, (4.0 ± 0.3) × 10³ M^-1s^-1, (2.5 ± 0.2) × 10³ M^-1s^-1 and <1 M^-1s^-1, respectively. The effect of buffer type and concentration was investigated with acetate, phosphate and borate. All tested buffers promote the HOI reactions with phenols. The percentage of iodine incorporation for various (hydroxyl)phenolic compounds and two NOM extracts ranges from 5% to 98%, indicating that electrophilic aromatic substitution and/or electron transfer can occur. The extent of these reactions depends on the number and relative position of the hydroxyl moieties on the phenolic compounds. Iodoform formation rates increase with increasing pH and iodoform yields increase from 9% to 67% for pH 6.0-10.0 for the HOI/3-OPA reactions. In the permanganate/HOI/3-OPA and permanganate/iodide/3-OPA system at pH < 8.0, iodoform formation is elevated compared to the HOI/3-OPA system in absence of permanganate. For pH > 8.0, in presence of permanganate, iodoform formation is significantly inhibited and iodate formation enhanced, which is due to a faster permanganate-mediated HOI disproportionation to iodate compared to the iodination process. The production of reactive iodine in real waters containing iodide in contact with permanganate may lead to the formation of iodinated organic compounds.

Probing and Comparing the Photobromination and Photoiodination of Dissolved Organic Matter by Using Ultra-High-Resolution Mass Spectrometry

Photochemical halogenation of dissolved organic matter (DOM) may represent an important abiotic process for the formation of natural organobromine compounds (OBCs) and natural organoiodine compounds (OICs) within surface waters. Here we report the enhanced formation of OBCs and OICs by photohalogenating DOM in freshwater and seawater, as well as the noticeable difference in the distribution and composition pattern of newly formed OBCs and OICs. By using negative ion electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry, various OBCs and OICs were identified during the photohalogenation processes in sunlit waters. The respective number of OBCs and OICs formed in artificial seawater (ASW) under light radiation was higher than that in artificial freshwater (AFW), suggesting a possible role of the mixed reactive halogen species. OBCs were formed mainly via substitution reactions and addition reactions accompanied by other reactions and distributed into three classes: unsaturated hydrocarbons with relatively low oxygen content, unsaturated aliphatic compounds, and saturated fatty acids and carbohydrates with relatively high hydrogen content. Unlike the OBCs, OICs were located primarily in the region of carboxylic-rich alicyclic molecules composed of esterified phenolic, carboxylated, and fused alicyclic structures and were generated mainly through electrophilic substitution of the aromatic proton. Our findings call for further investigation on the exact structure and toxicity of the OBCs and OICs generated in the natural environment.

Decomposition of Iodinated Pharmaceuticals by UV-254 nm-assisted Advanced Oxidation Processes

Iodinated pharmaceuticals, thyroxine (a thyroid hormone) and diatrizoate (an iodinated X-ray contrast medium), are among the most prescribed active pharmaceutical ingredients. Both of them have been reported to potentially disrupt thyroid homeostasis even at very low concentrations. In this study, UV-254 nm-based photolysis and photochemical processes, i.e., UV only, UV/H₂O₂, and UV/S₂O₈^2-, were evaluated for the destruction of these two pharmaceuticals. Approximately 40% of 0.5μM thyroxine or diatrizoate was degraded through direct photolysis at UV fluence of 160mJcm^-2, probably resulting from the photosensitive cleavage of C-I bonds. While the addition of H₂O₂ only accelerated the degradation efficiency to a low degree, the destruction rates of both chemicals were significantly enhanced in the UV/S₂O₈^2- system, suggesting the potential vulnerability of the iodinated chemicals toward UV/S₂O₈^2- treatment. Such efficient destruction also occurred in the presence of radical scavengers when biologically treated wastewater samples were used as reaction matrices. The effects of initial oxidant concentrations, solution pH, as well as the presence of natural organic matter (humic acid or fulvic acid) and alkalinity were also investigated in this study. These results provide insights for the removal of iodinated pharmaceuticals in water and/or wastewater using UV-based photochemical processes.

Selection and applicability of quenching agents for the analysis of polar iodinated disinfection byproducts

Iodide is widely present in drinking water sources as well as wastewater effluents. Chlorination and chloramination are the most commonly used disinfection methods. During chlorination or chloramination of drinking water/wastewater effluents, iodide may be oxidized to hypoiodous acid, which may further react with organic matter to form iodinated disinfection byproducts (DBPs). Recently, several new polar iodinated DBPs have been identified in drinking water as well as chlorinated wastewater effluents, and they have drawn increasing concerns due to their high toxicity. In DBPs studies, the selection of an appropriate quenching agent is critical to prevent further formation or any decomposition of DBPs during the holding time between sample collection and analysis. A previous study reported the applicability of different quenching agents for the analysis of various categories of chlorinated and brominated DBPs. But the applicability of quenching agents for the analysis of polar iodinated DBPs has not been reported. In this study, four different quenching agents (sodium sulfite, sodium thiosulfate, ascorbic acid and sodium borohydride) were tested for their suitability for the analysis of polar iodinated DBPs, and ascorbic acid was selected as the suitable quenching agent. Furthermore, it was found that ascorbic acid was applicable for the analysis of polar iodinated DBPs under the quenching agent doses of 0-0.42 mmol/L (stoichiometric amounts equivalent to 0-30 mg/L Cl2), contact times within 24 h, and pHs in the range of 6-8. Therefore, ascorbic acid was a widely applicable quenching agent for the analysis of polar iodinated DBPs under various conditions.

Kinetic and Mechanistic Aspects of the Reactions of Iodide and Hypoiodous Acid with Permanganate: Oxidation and Disproportionation

Oxidation kinetics of iodide and HOI/OI(-) by permanganate were studied in the pH range of 5.0-10.0. Iodide oxidation and iodate formation were faster at lower pH. The apparent second-order rate constants (k(obs)) for iodide oxidation by permanganate decrease with increasing pH from 29 M(-1) s(-1) at pH 5.0 and 6.9 M(-1) s(-1) at pH 7.0 to 2.7 M(-1) s(-1) at pH 10.0. k(obs) for HOI abatement are 56 M(-1) s(-1) at pH 5.0, 2.5 M(-1) s(-1) at pH 7.0, and 173 M(-1) s(-1) at pH 10.0. Iodate yields over HOI abatement decrease from 98% at pH 6.0 to 33% for pH ≥ 9.5, demonstrating that HOI disproportionation dominates HOI transformation by permanganate at pH ≥ 8.0. MnO2 formed as a product from permanganate reduction, oxidizes HOI to iodate for pH < 8.0, and promotes HOI disproportionation for pH ≥ 8.0. The rate of HOI oxidation or disproportionation induced by MnO2 is much lower than for permanganate. During treatment of iodide-containing waters, the potential for iodinated disinfection byproducts (I-DBPs) formation is highest at pH 7.0-8.0 due to the long lifetime of HOI. For pH < 6.0, HOI/I2 is quickly oxidized by permanganate to iodate, whereas for pH ≥ 8.0, HOI/OI(-) undergoes a fast permanganate-mediated disproportionation.

A comparison of iodinated trihalomethane formation from chlorine, chlorine dioxide and potassium permanganate oxidation processes

This study compared the formation of iodinated trihalomethanes (I-THMs) from iodide-containing raw waters oxidized by chlorine, chlorine dioxide (ClO₂) and potassium permanganate (KMnO₄) at different oxidant concentrations, reaction times, pHs, initial iodide concentrations and bromide to iodide mass ratios. Among the six investigated I-THMs, iodoform was the major species formed during the oxidation using chlorine, ClO₂ and KMnO₄. When oxidant concentration increased from 0.1 to 3.0 mg/L, the formation of I-THMs increased and then decreased for chlorine and ClO₂, but kept increasing for KMnO₄. As the reaction time went by, I-THM concentration increased to a plateau within 10 h (ClO₂ within only 1 h, especially) for all the three oxidants. I-THM formation gradually increased from pH 3.0 to 9.0 and remained stable at pH values higher than 7.5 for chlorine; however, for ClO₂ and KMnO₄ the highest I-THM formation showed at pH 7.0 and 7.5, respectively. As initial iodide concentration increased from 20 to 800 μg/L, the total amount and species of I-THMs increased for the three oxidants. Iodide contributed to I-THM formation much more significantly than bromide.

Chlorination of iodide-containing waters in the presence of CuO: formation of periodate

It has been shown previously that the disproportionation of halogen-containing oxidants (e.g., HOCl, HOBr, and ClO2) is enhanced by a CuO-catalyzed process. In this study, the transformation of iodine during chlorination in the presence of CuO was investigated. There is no significant enhancement of the disproportionation of hypoiodous acid (HOI) in the presence of CuO. The formation rate of iodate (IO3(-)) in the CuO-HOCl-I(-) system significantly increased when compared to homogeneous solutions, which was ascribed to the activation of HOCl by CuO enhancing its reactivity toward HOI. In this reaction system, iodate formation rates increase with increasing CuO (0-0.5 g L(-1)) and bromide (0-2 μM) doses and with decreasing pH (9.6-6.6). Iodate does not adsorb to the CuO surfaces used in this study. Nevertheless, iodate concentrations decreased after a maximum was reached in the CuO-HOCl-I(-)(-Br(-)) systems. Similarly, the iodate concentrations decrease as a function of time in the CuO-HOCl-IO3(-) or CuO-HOBr-IO3(-) system, and the rates increase with decreasing pH (9.6-6.6) due to the enhanced reactivity of HOCl or HOBr in the presence of CuO. It could be demonstrated that iodate is oxidized to periodate by a CuO-activated hypohalous acid, which is adsorbed on the CuO surface. No periodate could be measured in filtered solutions because it was mainly adsorbed to CuO. The adsorbed periodate was identified by scanning electron microscopy plus energy dispersive spectroscopy and X-ray photoelectron spectroscopy.

Optimal iodine staining of cardiac tissue for X-ray computed tomography

X-ray computed tomography (XCT) has been shown to be an effective imaging technique for a variety of materials. Due to the relatively low differential attenuation of X-rays in biological tissue, a high density contrast agent is often required to obtain optimal contrast. The contrast agent, iodine potassium iodide (), has been used in several biological studies to augment the use of XCT scanning. Recently was used in XCT scans of animal hearts to study cardiac structure and to generate 3D anatomical computer models. However, to date there has been no thorough study into the optimal use of as a contrast agent in cardiac muscle with respect to the staining times required, which has been shown to impact significantly upon the quality of results. In this study we address this issue by systematically scanning samples at various stages of the staining process. To achieve this, mouse hearts were stained for up to 58 hours and scanned at regular intervals of 6–7 hours throughout this process. Optimal staining was found to depend upon the thickness of the tissue; a simple empirical exponential relationship was derived to allow calculation of the required staining time for cardiac samples of an arbitrary size.

Reduction of the nitro group to amine by hydroiodic acid to synthesize o-aminophenol derivatives as putative degradative markers of neuromelanin

Neuromelanin (NM) is produced in dopaminergic neurons of the substantia nigra (SN) and in noradrenergic neurons of the locus coeruleus (LC). The synthesis of NM in those neurons is a component of brain aging and there is the evidence that this pigment can be involved in the pathogenesis of neurodegenerative diseases such as Parkinson’s disease. NM is believed to derive from the oxidative polymerization of dopamine (DA) or norepinephrine (NE) with the participation of cysteine, dolichols and proteins. However, there are still unknown aspects in the chemical structure of NM from SN (SN-NM) and LC (LC-NM). In this study, we designed a new method to synthesize o-aminophenol compounds as putative degradation products of catecholamines and their metabolites which may be incorporated into NM. Those compounds are aminohydroxyphenylethylamine (AHPEA) isomers, aminohydroxyphenylacetic acid (AHPAA) isomers and aminohydroxyethylbenzene (AHEB) isomers, which are expected to arise from DA or NE, 3,4-dihydroxyphenylacetic acid (DOPAC) or 3,4-dihydroxyphenylmandelic acid (DOMA) and 3,4-dihydroxyphenylethanol (DOPE) or 3,4-dihydroxyphenylethyleneglycol (DOPEG), respectively. These o-aminophenol compounds were synthesized by the nitration of phenol derivatives followed by reduction with hydroiodic acid (HI), and they could be identified by HPLC in HI hydrolysates of SN-NM and LC-NM. This degradative approach by HI hydrolysis allows the identification of catecholic precursors unique to SN-NM and LC-NM, which are present in catecholaminergic neurons.

Factors affecting the formation of iodo-trihalomethanes during oxidation with chlorine dioxide

Effects of water characteristics, reaction time, temperature, bromide and iodide ion concentrations, oxidant doses, and pH on formation of iodinated trihalomethanes (I-THM) during oxidation of iodide-containing water with chlorine dioxide (ClO2) were investigated. Among the water samples collected from ten water sources, iodoform (CHI3) was the predominant I-THM and trace amount of chlorodiiodomethane (CHClI2) was occasionally found. CHI3 yields correlated moderately with specific UV absorbance (SUVA) (R(2)=0.79), indicating that hydrophobic aromatic content were important precursors. Longer reaction time led to continued formation of CHI3. I-THM containing bromide was also found in waters containing both bromide and iodide, but CHI3 was dominant. The formation of CHI3 was higher at 25°C than 5°C and 35°C. CHI3 formation showed an increase followed by a decrease trend with increasing ClO2 doses and iodide concentrations and the highest yields occurred at iodide to ClO2 molar ratios of 1-2. pH 8 resulted in the highest CHI3 formation. It should be noted that a high iodide concentration was spiked to waters before adding ClO2 and the results may not reflect the formation yields of iodinated THMs in real conditions, but they provide information about formation trend of I-THM during oxidation of ClO2.

Determination of iodide, iodate and organo-iodine in waters with a new total organic iodine measurement approach

The dissolved iodine species that dominate aquatic systems are iodide, iodate and organo-iodine. These species may undergo transformation to one another and thus affect the formation of iodinated disinfection byproducts during disinfection of drinking waters or wastewater effluents. In this study, a fast, sensitive and accurate method for determining these iodine species in waters was developed by derivatizing iodide and iodate to organic iodine and measuring organic iodine with a total organic iodine (TOI) measurement approach. Within this method, organo-iodine was determined directly by TOI measurement; iodide was oxidized by monochloramine to hypoiodous acid and then hypoiodous acid reacted with phenol to form organic iodine, which was determined by TOI measurement; iodate was reduced by ascorbic acid to iodide and then determined as iodide. The quantitation limit of organo-iodine or sum of organo-iodine and iodide or sum of organo-iodine, iodide and iodate was 5 μg/L as I for a 40 mL water sample (or 2.5 μg/L as I for an 80 mL water sample, or 1.25 μg/L as I for a 160 mL water sample). This method was successfully applied to the determination of iodide, iodate and organo-iodine in a variety of water samples, including tap water, seawater, urine and wastewater. The recoveries of iodide, iodate and organo-iodine were 91-109%, 90-108% and 91-108%, respectively. The concentrations and distributions of iodine species in different water samples were obtained and compared.

Conversion of iodide to hypoiodous acid and iodine in aqueous microdroplets exposed to ozone

Halides are incorporated into aerosol sea spray, where they start the catalytic destruction of ozone (O3) over the oceans and affect the global troposphere. Two intriguing environmental problems undergoing continuous research are (1) to understand how reactive gas phase molecular halogens are directly produced from inorganic halides exposed to O3 and (2) to constrain the environmental factors that control this interfacial process. This paper presents a laboratory study of the reaction of O3 at variable iodide (I(-)) concentration (0.010-100 μM) for solutions aerosolized at 25 °C, which reveal remarkable differences in the reaction intermediates and products expected in sea spray for low tropospheric [O3]. The ultrafast oxidation of I(-) by O3 at the air-water interface of microdroplets is evidenced by the appearance of hypoiodous acid (HIO), iodite (IO2(-)), iodate (IO3(-)), triiodide (I3(-)), and molecular iodine (I2). Mass spectrometry measurements reveal an enhancement (up to 28%) in the dissolution of gaseous O3 at the gas-liquid interface when increasing the concentration of NaI or NaBr from 0.010 to 100 μM. The production of iodine species such as HIO and I2 from NaI aerosolized solutions exposed to 50 ppbv O3 can occur at the air-water interface of sea spray, followed by their transfer to the gas-phase, where they contribute to the loss of tropospheric ozone.

Passivated iodine pentoxide oxidizer for potential biocidal nanoenergetic applications

Iodine pentoxide (I2O5), also known as diiodine pentoxide, is a strong oxidizer which has been recently proposed as an iodine-rich oxidizer in nanoenergetic formulations, whose combustion products lead to molecular iodine as a biocidal agent. However, its highly hygroscopic nature hinders its performance as a strong oxidizer and an iodine releasing agent and prevents its implementation. In this work, we developed a gas phase assisted aerosol spray pyrolysis which enables creation of iron oxide passivated I2O5. Transmission electron microscopy elemental imaging as well as temperature-jump mass spectrometry confirmed the core shell nature of the material and the fact that I2O5 could be encapsulated in pure unhydrated form. Combustion performance finds an optimal coating thickness that enables combustion performance similar to a high performing CuO based thermite.

Application of micro-computed tomography with iodine staining to cardiac imaging, segmentation, and computational model development

Micro-computed tomography (micro-CT) has been widely used to generate high-resolution 3-D tissue images from small animals nondestructively, especially for mineralized skeletal tissues. However, its application to the analysis of soft cardiovascular tissues has been limited by poor inter-tissue contrast. Recent ex vivo studies have shown that contrast between muscular and connective tissue in micro-CT images can be enhanced by staining with iodine. In the present study, we apply this novel technique for imaging of cardiovascular structures in canine hearts. We optimize the method to obtain high-resolution X-ray micro-CT images of the canine atria and its distinctive regions-including the Bachmann's bundle, atrioventricular node, pulmonary arteries and veins-with clear inter-tissue contrast. The imaging results are used to reconstruct and segment the detailed 3-D geometry of the atria. Structure tensor analysis shows that the arrangement of atrial fibers can also be characterized using the enhanced micro-CT images, as iodine preferentially accumulates within the muscular fibers rather than in connective tissues. This novel technique can be particularly useful in nondestructive imaging of 3-D cardiac architectures from large animals and humans, due to the combination of relatively high speed ( ~ 1 h/per scan of the large canine heart) and high voxel resolution (36 μm) provided. In summary, contrast micro-CT facilitates fast and nondestructive imaging and segmenting of detailed 3-D cardiovascular geometries, as well as measuring fiber orientation, which are crucial in constructing biophysically detailed computational cardiac models.

Application of hypoiodite-mediated aminyl radical cyclization to synthesis of solasodine acetate

Solasodine acetate, an anticancer steroidal alkaloid, was synthesized from diosgenin in 8 steps with an overall yield of 23%. A key synthetic step involves the formation of 5/6-oxazaspiroketal moiety via hypoiodite-mediated aminyl radical cyclization of a steroidal primary amine.

Selective reduction of biomass by hydriodic acid and its in situ regeneration from iodine by metal/hydrogen

HI returns: Hydroiodic acid is a highly selective reducing reagent for a wide variety of substrates. Its application is limited by the formation of iodine and the difficulty in reconverting that iodione back to HI in situ. We report the facile conversion of I(2) to HI by metal-catalyzed hydrogenation in the presence of water, and demonstrate the utility of this process in the conversion of fructose to 5-methyfurfural and glycerol to 2-iodopropane.

Effects of select anions from the Hofmeister series on the gas-phase conformations of protein ions measured with traveling-wave ion mobility spectrometry/mass spectrometry

The gas-phase conformations of ubiquitin, cytochrome c, lysozyme, and α-lactalbumin ions, formed by electrospray ionization (ESI) from aqueous solutions containing 5 mM ammonium perchlorate, ammonium iodide, ammonium sulfate, ammonium chloride, ammonium thiocyanate, or guanidinium chloride, are examined using traveling-wave ion mobility spectrometry (TWIMS) coupled to time-of-flight (TOF) mass spectrometry (MS). For ubiquitin, cytochrome c, and α-lactalbumin, adduction of multiple acid molecules results in no significant conformational changes to the highest and lowest charge states formed from aqueous solutions, whereas the intermediate charge states become more compact. The transition to more compact conformers for the intermediate charge states occurs with fewer bound H(2)SO(4) molecules than HClO(4) or HI molecules, suggesting ion-ion or salt-bridge interactions are stabilizing more compact forms of the gaseous protein. However, the drift time distributions for protein ions of the same net charge with the highest levels of adduction of each acid are comparable, indicating that these protein ions all adopt similarly compact conformations or families of conformers. No significant change in conformation is observed upon the adduction of multiple acid molecules to charge states of lysozyme. These results show that the attachment of HClO(4), HI, or H(2)SO(4) to multiply protonated proteins can induce compact conformations in the resulting gas-phase protein ions. In contrast, differing Hofmeister effects are observed for the corresponding anions in solution at higher concentrations.

Formation of toxic iodinated disinfection by-products from compounds used in medical imaging

Iodinated X-ray contrast media (ICM) were investigated as a source of iodine in the formation of iodo-trihalomethane (iodo-THM) and iodo-acid disinfection byproducts (DBPs), both of which are highly genotoxic and/or cytotoxic in mammalian cells. ICM are widely used at medical centers to enable imaging of soft tissues (e.g., organs, veins, blood vessels) and are designed to be inert substances, with 95% eliminated in urine and feces unmetabolized within 24 h. ICM are not well removed in wastewater treatment plants, such that they have been found at elevated concentrations in rivers and streams (up to 100 μg/L). Naturally occurring iodide in source waters is believed to be a primary source of iodine in the formation of iodo-DBPs, but a previous 23-city iodo-DBP occurrence study also revealed appreciable levels of iodo-DBPs in some drinking waters that had very low or no detectable iodide in their source waters. When 10 of the original 23 cities' source waters were resampled, four ICM were found--iopamidol, iopromide, iohexol, and diatrizoate--with iopamidol most frequently detected, in 6 of the 10 plants sampled, with concentrations up to 2700 ng/L. Subsequent controlled laboratory reactions of iopamidol with aqueous chlorine and monochloramine in the absence of natural organic matter (NOM) produced only trace levels of iodo-DBPs; however, when reacted in real source waters (containing NOM), chlorine and monochloramine produced significant levels of iodo-THMs and iodo-acids, up to 212 nM for dichloroiodomethane and 3.0 nM for iodoacetic acid, respectively, for chlorination. The pH behavior was different for chlorine and monochloramine, such that iodo-DBP concentrations maximized at higher pH (8.5) for chlorine, but at lower pH (6.5) for monochloramine. Extracts from chloraminated source waters with and without iopamidol, as well as from chlorinated source waters with iopamidol, were the most cytotoxic samples in mammalian cells. Source waters with iopamidol but no disinfectant added were the least cytotoxic. While extracts from chlorinated and chloraminated source waters were genotoxic, the addition of iopamidol enhanced their genotoxicity. Therefore, while ICM are not toxic in themselves, their presence in source waters may be a source of concern because of the formation of highly toxic iodo-DBPs in chlorinated and chloraminated drinking water.

Low-level bromate analysis in drinking water by ion chromatography with optimized suppressed conductivity cell current followed by a post-column reaction and UV/Vis detection

In the present work, a high capacity anion exchange column was used to efficiently and simultaneously separate traces of oxyhalide disinfection byproducts (DBP) anions and bromide by an ion chromatography system followed by a post-column reaction (PCR). The PCR generates in situ hydroiodic (HI) acid from the excess of potassium iodate that combines with bromate from the column effluent to form the triiodide anion detectable by UV/Vis absorbance at 352 nm. The suppressed conductivity cell current was optimized at 70 mA, with a flow rate of 1.0 mL/min and a 9 mM carbonate eluent. Its performance was investigated on a trace-level determination of bromate in ozonated municipal and bottled drinking water. Based on ozonated municipal drinking water matrix, the method detection limit of 0.27 μg BrO(-)(3)/L was evaluated with the Method Quantification Limit (MQL) of 0.89 μg BrO(-)(3)/L. However, in ultrapure water, a MDL of 0.015 μg BrO(-)(3)/L and a MRL of 0.052 μg BrO(-)(3)/L were achieved. The recovery for spiked municipal samples was in the range of 90%-115%.

Presence and partitioning behavior of polyfluorinated iodine alkanes in environmental matrices around a fluorochemical manufacturing plant: another possible source for perfluorinated carboxylic acids?

The indistinct origins of some ubiquitous perfluorinated alkyl acids have attracted great attention in recent decades. In this present work, even-chained polyfluorinated iodides (PFIs), a group of volatile perfluorinated compounds (PFCs), including four perfluorinated iodine alkanes (FIAs) and three polyfluorinated telomer iodides (FTIs) were confirmed to be present in the environment. A wide concentration range was found for FIAs at 1.41 to 3.08x10(4) pg/L, and for FTIs at 1.39 to 1.32x10(3) pg/L in the ambient air collected around a fluorochemical manufacturing plant in Shandong province, northern China. Whereas for surface soils, most of these PFIs were below detection limits and only small amounts of analytes with higher carbon chain (such as perfluorododecyl iodide and 1H,1H,2H,2H-perfluorodecyl iodide, 16.6-499 pg/g) could be sporadically detected. The presence of the PFIs in different environmental matrices in the investigated area and calculated vapor pressures (0.095-20.4 Torr) verify that they can be considered as volatile organic chemicals and easily be released into the atmosphere. Together with reported degradation ability and long-range transport potential, the identification of these PFIs indicates that unintentional release during the telomer reaction process might also be another route for the formation and distribution of certain polyfluorinated alcohols, aldehydes, and carboxylic acid derivatives under oxidative conditions in the environment.

Novel and sensitive methods for the determination of dopamine based on the resonance Rayleigh scattering, second-order scattering and frequency doubling scattering quenching effects

Three novel methods were designed for the determination of dopamine (DA) by means of the quenching effects on resonance Rayleigh scattering (RRS) and non-linear scattering such as second-order scattering (SOS) and frequency doubling scattering (FDS) intensities. In Britton-Robinson buffer medium (pH 6.02), I(3)(-) could react with DA to produce I(-), which resulted in the decreases of the RRS, SOS and FDS intensities of the ethyl violet (EV)-I(3)(-) system, and the decreases of scattering intensity (DeltaI) were directly proportional to the concentrations of DA in a certain range. The detection limit (3sigma) for DA was 0.0195 micromol/L for the RRS method, 0.286 micromol/L for the SOS method and 0.0985 micromol/L for the FDS method, respectively. In this work, the characteristics of absorption, RRS, SOS and FDS spectra of this reaction have been studied; the optimum reaction condition and influencing factors have been investigated. The methods were applied to the determination of DA in pharmaceutical samples with satisfactory results.

Total synthesis of (+)-azaspiracid-1. An exhibition of the intricacies of complex molecule synthesis

The synthesis of the marine neurotoxin azaspiracid-1 has been accomplished. The individual fragments were synthesized by catalytic enantioselective processes: A hetero-Diels-Alder reaction to afford the E- and HI-ring fragments, a carbonyl-ene reaction to furnish the CD-ring fragment, and a Mukaiyama aldol reaction to deliver the FG-ring fragment. The subsequent fragment couplings were accomplished by aldol and sulfone anion methodologies. All ketalization events to form the nonacyclic target were accomplished under equilibrating conditions utilizing the imbedded configurations of the molecule to adopt one favored conformation. A final fragment coupling of the anomeric EFGHI-sulfone anion to the ABCD-aldehyde completed the convergent synthesis of (+)-azaspiracid-1.

Nanoparticulate carrier containing water-insoluble iodinated oil as a multifunctional contrast agent for computed tomography imaging

Contrast-enhanced computed tomography (CT) imaging is a valuable and routine strategy for the clinical diagnosis of various diseases. However, all current CT contrast agents are liquids, so they flow through the blood vessels and disappear very quickly by extravasation. If it were possible to make a blood-compatible particulate contrast agent, we could highlight a particular tissue by either passive or active targeting. In this work, Pluronic F127 and a naturally iodinated compound, Lipiodol, were used to form radiopaque nanoreservoir structures. The resultant nanoparticles have a stable structure at high concentrations, sufficient X-ray absorption, a safety profile similar to or better than that of Iopromide, and a longer circulation time than commercial iodinated preparations. The utility of the resultant radiopaque nanoparticles as a contrast agent was tested using micro-SPECT/CT imaging in vivo. Together with the very good solubility of hydrophobic drugs (e.g., Taxol) in Lipiodol, these results suggest the possibility that these particulate structures and their bioconjugates could become functional CT contrast agents that could deliver therapeutic agents to a particular tissue.

Characterization of chitosan thiolation and application to thiol quantification onto nanoparticle surface

The objective of the present work was to establish a simple and appropriated method for the quantification of thiol groups standing on the surface of core-shell nanoparticles elaborated with poly(isobutyl cyanoacrylates) and thiolated chitosan. A critical analysis of the widely used Ellman's method for the determination of thiol groups in various compounds was made. The reduced solubility of the thiolated polymer at the optimal pH of the Ellman's assay (pH 8-8.5) made difficult the accessibility of the Ellman's reagent to thiol groups in the cross-linked polymer. Furthermore, the lack of stability of the Ellman's reaction with time lead to the conclusion that the Ellman's method was of limited value to evaluate thiol groups in thiolated polymers like thiolated chitosan. An alternative and very simple thiol quantification method was developed on the bases of the classical iodine titration. The new method allowed the determination of thiol groups in small amount of samples at acidic pH, and the monitoring of the thiol determination kinetic with time. It was successfully applied to the quantification of active thiol groups on the surface of poly(isobutyl cyanoacrylates) nanoparticles coated with thiol chitosan.

Novel 10-I-3 hypervalent iodine-based compounds for electrophilic trifluoromethylation

The synthesis of a new family of 10-I-3 hypervalent iodine compounds is described in which the CF3 functionality participates directly in the hypervalent bond. These materials are accessible by nucleophilic ligand substitution at iodine using Me3SiCF3 in the presence of a substoichiometric amount of fluoride. The expected T-shaped geometry at iodine was verified by X-ray crystallographic analyses of three of the products (1-trifluoromethyl-1,2-benziodoxol-3-(1 H)-one and two substituted 1-trifluoromethyl-1,3-dihydro-1,2-benziodoxoles). Preliminary results for the direct electrophilic transfer of the trifluoromethyl moiety onto organic nucleophiles show modest reactivity in polar aprotic solvents under relatively mild conditions. The overall process can be understood as a formal umpolung of the CF3 group.

Synthesis and photochemistry of 1-iodocyclohexene: influence of ultrasound on ionic vs. radical behaviour

Simultaneous application of UV light and ultrasonic irradiation to a reaction mixture containing 1-iodocyclohexene is reported. The irradiation of 1-iodocyclohexene in methanol was carried out with or without addition of zinc. The effect of ultrasound or mechanical stirring on this solid-liquid system was also compared. The irradiation of 1-iodocyclohexene in methanol in the presence of zinc increases the yield of the nucleophilic trapping product, compared with the yield after irradiation in the absence of zinc. The photodegradation of 1-iodocyclohexene was slightly accelerated after addition of zinc. A rapid formation of radical product was accompanied by substantial decrease of 1-iodocyclohexene after application of ultrasound and irradiation without the zinc. The ultrasound significantly affects the photobehaviour of this reaction, predominantly its radical route. The joint application of ultrasound and zinc contributes positively to the production of radical and ionic products. The sonochemical stirring is more effective than mechanical stirring.

Heterogeneous reactions of HOI, ICl and IBr on sea salt and sea salt proxies

The heterogeneous chemistry of HOI, ICl and IBr on sea salt and sea salt proxies has been studied at 274 K using two experimental approaches: a wetted wall flow tube coupled to an electron impact mass spectrometer (WWFT-MS) and an aerosol flow tube (AFT) coupled to a differential mobility analyser (DMA) and a chemical ionisation mass spectrometer (CIMS). Uptake of all three title molecules into bulk aqueous halide salt films was rapid and controlled by gas phase diffusion. Uptake of HOI gave rise to gas-phase ICl and IBr, with the latter being the predominant product whenever Br(-) was present. Only partial release of IBr was observed due to high solubility of dihalogens in the film. ICl uptake gave the same yield of IBr as HOI uptake. Uptake of ICl on NaBr aerosol was accommodation limited with alpha = 0.018 +/- 0.004 and gas phase IBr product has a yield of 0.6 +/- 0.3. The results show that HOI can act as a catalyst for activation of bromine from sea-salt aerosols in the marine boundary layer, via the reactions: HOI(aq) + Cl + H--> ICl(aq) + H(2)O(l) and ICl(aq) + Br--> IBr(aq) + Cl.

Hypersensitivity Reactions to Iodinated Contrast Media

Adverse reactions after iodinate contrast media (ICM) administration have been observed, which can be classified as immediate (i.e., occurring within one hour after administration) and delayed or non-immediate (i.e., occurring more than one hour after administration). Even though the incidence of ICM adverse reactions has been significantly reduced by the introduction of non-ionic compounds, immediate reactions still occur in about 3% of administrations. Different pathogenic mechanisms have been suggested for ICM reactions, including immunologic ones. Basophils and mast cells participate in immediate reactions through the release of mediators like histamine and tryptase, whereas a T-cell-mediated pathogenic mechanism is involved in most non-immediate reactions, particularly maculopapular rashes. Skin tests and specific IgE assays are carried out to diagnose immediate hypersensitivity reactions, while both delayed-reading intradermal tests and patch tests are usually performed to evaluate non-immediate reactions. However, in vitro specific IgE assays are not commercially available. As far as in vitro tests are concerned, a response involving ICM-related T-cell activity may be assessed by the lymphocyte transformation test. Allergologic evaluation appears to be indicated in hypersensitivity reactions to ICM, although the sensitivity, specificity, and predictive values of allergologic tests have not yet been established. This paper summarizes the current state of the art and addresses the research that is still needed on the pathogenic mechanisms, diagnosis, and prevention of ICM-induced hypersensitivity reactions.

An in vitro study of antimicrobial activity and efficacy of iodine-generating hydrogel dressings

OBJECTIVE

To determine the antimicrobial activity and efficacy of different formulations of novel bioxygenating hydrogel dressings (which deliver both iodine and oxygen into the wound) against various target organisms by means of an in vitro test system that more effectively mimics the conditions encountered when dressings are in contact with wounds.

METHOD

Three bioxygenating hydrogels were tested: Oxyzyme, which releases low levels of iodine into the wound, and Iodozyme 402 and Iodozyme 401, which release higher levels of iodine, with Iodozyme 402 releasing twice the amount of 401. Cellulose filter disks (n = 32) were inoculated with indicator species and placed equidistant from each other as a matrix onto agar test beds. Cut squares of control or test dressings were placed on top of each disk. Kill curves were constructed from determinations of the numbers of survivors (log cfu per disk) over time by removing disk samples at various time points.

RESULTS

Significant differences (p < 0.05) were observed between the controls and test samples. The order of sensitivity for Oxyzyme was Fusobacterium nucleatum, Bacteroides fragilis, Propionibacterium acnes, Staphylococcus epidermidis, methicillin-resistant Staphylococcus aureus (MRSA), Candida albicans and Pseudomonas aeruginosa. The order of efficacy of the three hydrogel dressings (Iodozyme 402, followed by Iodozyme 401 and then Oxyzyme) was the same regardless of the target species.

CONCLUSION

The novel hydrogel skin surface wound dressings are broad-spectrum in activity, encompassing antibiotic-resistant organisms, anaerobes and yeasts; their antimicrobial function appears to be rapidly effective.

Quantitative treatment of coarsely binned low-resolution recordings in molecular absorption spectroscopy

Optical multichannel detectors like photodiode arrays or CCD cameras combined with grating spectrometers are commonly used as detection systems in quantitative absorption spectroscopy. As a trade-off to broad spectral coverage, banded spectral features are sometimes recorded with insufficient spectral resolution and/or insufficiently fine detector binning. This renders the true physical spectrum of recorded intensities changed by instrumental and spectrum specific artefacts thus impeding comparability between results from different set-ups. In this work, it is demonstrated that in the case of a "well-behaved"--i.e. free of ro-vibronic structure--absorption band like the iodine monoxide IO(4<--0) transition, these effects can easily change the apparent peak absorption by up to 50%. Also deviations from the strict linearity (Beer-Lambert's law) between absorber concentration and apparent, i.e. pixelwise optical density occur. This can be critical in studies of chemical kinetics. It is shown that the observed non-linearity can cause errors of up to 50% in the determination of a second order rate coefficient for the IO self reaction. To overcome the problem, a consistent and rigorous integral approach for the treatment of intensity recordings is developed. Linearity between optical density and absorber concentration thereby is re-established. The method is validated using artificial test data as well as experimental data of the IO(4<--0) absorption transition, obtained in the context of I2/O3 photochemistry studies. The agreement is accurate to within +/-2% (test data) and +/-3% (experimental data) supporting the validity of the approach. Possible consequences for other spectroscopic work are indicated.

Diversity-Oriented Synthesis of 3-Iodochromones and Heteroatom Analogues via ICl-Induced Cyclization

The ICl-induced cyclization of heteroatom-substituted alkynones provides a simple, highly efficient approach to various 3-iodochromones and analogues. This process is run under mild conditions, tolerates various functional groups, and generally provides chromones in good to excellent yields. Subsequent palladium-catalyzed transformations afford a rapid increase in molecular complexity and a convenient preparation of a wide range of functionally substituted chromones, furans, and polycyclic compounds. Iodothiochromenones and iodoquinolinones are also prepared by similar ICl-induced cyclizations.

Laser induced fluorescence studies of iodine oxide chemistry : Part II. The reactions of IO with CH3O2, CF3O2 and O3

The technique of pulsed laser photolysis was coupled to laser induced fluorescence detection of iodine oxide (IO) to measure rate coefficients, k for the reactions IO + CH(3)O(2)--> products (R1, 30-318 Torr N(2)), IO + CF(3)O(2)--> products (R2, 70-80 Torr N(2)), and IO + O(3)--> OIO + O(2) (R3a). Values of k(1) = (2 +/- 1) x 10(-12) cm(3) molecule(-1) s(-1), k(2) = (3.6 +/- 0.8) x 10(-11) cm(3) molecule(-1) s(-1), and k(3a) <5 x 10(-16) cm(3) molecule(-1) s(-1) were obtained at T = 298 K. In the course of this work, the product yield of IO from the reaction of CH(3)O(2) with I was determined to be close to zero, whereas CH(3)OOI was formed efficiently at 70 Torr N(2). Similarly, no evidence was found for IO formation in the CF(3)O(2) + I reaction. An estimate of the rate coefficients k(CH(3)O(2) + I) = 2 x 10(-11) cm(3) molecule(-1) s(-1) and k(CH(3)OOI + I) = 1.5 x 10(-10) cm(3) molecule(-1) s(-1) was also obtained. The results on k(1)-k(3) are compared to the limited number of previous investigations and the implications for the chemistry of the marine boundary layer are briefly discussed.

Novel aziridination of olefins: direct synthesis from sulfonamides using t-BuOI

tert-Butyl hypoiodite (t-BuOI) was found to be a powerful reagent for synthesis of aziridines from olefins and sulfonamides. The aziridination of olefins was achieved by using sulfonamides with t-BuOI. Our preliminary findings represent the example of metal-free aziridination of olefins with readily accessible sulfonamides as a nitrogen source.

Concentrated hydriodic acid in simultaneous deprotections of multifunctional inositols

l-1-Deoxy-1-fluoro-6-O-methyl-myo-inositol was epimerized by chloral/DCC in boiling 1,2-dichloroethane yielding D-1-O-cyclohexylcarbamoyl-2-deoxy-2-fluoro-3-O-methyl-5,6-O-[(R/S)-2,2,2-trichloroethylidene]-chiro-inositol. The latter and l-4-O-benzyl-3-O-cyclohexylcarbamoyl-5-O-methyl-1,2-O-(2,2,2-trichloroethylidene)-muco-inositol, l-4-O-benzyl-3-O-cyclohexylcarbamoyl-1,2-O-ethylidene-5-O-methyl-muco-inositol, d-1-O-cyclohexylcarbamoyl-2-deoxy-5,6-O-ethylidene-2-fluoro-3-O-methyl-chiro-inositol, as well as D-5-O-benzyl-4-O-cyclohexylcarbamoyl-3-deoxy-3-(N,N'-dicyclohexylureido)-6-O-methyl-1,2-O-(2,2,2-trichloroethylidene)-chiro-inositol were deprotected with boiling 57% aq hydrogen iodide. Ether, urethane and ethylidene acetal functions were simultaneously cleaved by the reagent, whereas the trichloroethylidene groups were still intact or were only removed in small quantities. Especially, the urea function of D-5-O-benzyl-4-O-cyclohexylcarbamoyl-3-deoxy-3-(N,N'-dicyclohexylureido)-6-O-methyl-1,2-O-(2,2,2-trichloroethylidene)-chiro-inositol was decomposed to a cyclohexylamino group. The hydrodechlorination of D-1-O-cyclohexylcarbamoyl-2-deoxy-2-fluoro-3-O-methyl-5,6-O-[(R/S)-2,2,2-trichloroethylidene]-chiro-inositol using Raney-Nickel yielded a mixture of the corresponding 5,6-O-ethylidene- and 5,6-O-chloroethylidene derivatives. The three synthetic steps-hydrodehalogenation, HI-deprotection and peracylation- were combined without purification of the intermediates.

The novel and efficient direct synthesis of N,O-acetal compounds using a hypervalent iodine(III) reagent: an improved synthetic method for a key intermediate of discorhabdins

The use of hypervalent iodine(III) reagents allowed us to develop the novel and efficient direct synthesis of N,O-acetal compounds via the oxidative fragmentation reaction of alpha-amino acids or alpha-amino alcohols; furthermore, we succeeded in developing an improved synthesis of the key intermediate of discorhabdins.

Pd-catalyzed carbonyl insertion coupling reactions of a hypervalent iodoheterocycle with alcohols and amines

The palladium-catalyzed cross-coupling carbonyl insertion reaction between 3,7-bis(N,N-dimethylamino)-10H-dibenz[b,e]iodinium iodide (1) and alcohols or amines 2 is described. Some new amides and esters 3 containing an active iodo functional group have been prepared in 65-91% yields.

X-ray absorption spectroscopic studies on model compounds for biological iodine and bromine

X-ray absorption spectra of a number of organic iodine and bromine compounds of biological relevance, as well as of a series of iodine compounds with different oxidation states, have been measured. The iodine K-edge spectra (XANES) are found to be relatively featureless but the position of the edge is found to be sensitive to formal valence (among other factors), and the edge shape to the number of bound O atoms. EXAFS spectra of organohalogen compounds (both iodine and bromine) can be used to discriminate between aliphatic and aromatic compounds. There are differences both in the distances from the halogens to the first shell of C atoms, which are shorter for aromatic compounds, and in the patterns of shells in the Fourier transforms. This result is expected to be relevant to studies at these edges in biological systems.

Vasomotor effects of iodinated contrast media: just side effects?

Routinely used iodinated contrast media have complex vasomotor effects on several arterial districts. All classes of iodinated radiographic contrast media are vasoactive, with iso-osmolar dimers inducing the smallest changes in vascular tone. The mechanisms responsible for contrast-induced vasomotor changes are not fully elucidated and are likely to be multifactorial. Although contrast-induced vasomotility is usually considered as an unwanted "side effect", recent findings suggest that it might indeed be useful in exploring the functional integrity of the vessel wall. We found that atherosclerosis has an impact on the type of the contrast-induced coronary vasomotor reaction. In fact, angiographically normal coronary segments show divergent vasomotor reactions to iodixanol or iopromide according to the presence/absence of, and distance from, a coronary atherosclerotic lesion located in their proximity. The mechanism responsible for this vasomotor effect does not apparently involve flow-mediated vasodilatation or endothelial nitric oxide synthesis. On the other hand, a cyclooxygenase product may be, at least in part, responsible for the vasodilating effect of non-ionic agents on epicardial coronary arteries, since contrast-induced vasodilatation is strongly inhibited in the presence of indomethacin. These findings have potential clinical implications, since the analysis of contrast-induced coronary vasomotion might result in a new test capable of evaluating vascular functional integrity. Such a test might be alternative or complementary to the tests based on muscarinic agonists (acetylcholine) or serotonin, which are known to evaluate the nitric oxide pathway.

[Drinking water decontamination with isolative sorbent disinfectants]

Drinking water can be decontaminated with the use of isolative sorbent disinfectants. Consideration of the effectiveness of water disinfectants and the sorptive power of porous materials against bacteria and viruses attested to the favour of iodine and silver-containing disinfectants and their compositions on porous aggressive carriers to be employed in extreme conditions such as on board crewed space vehicles.