Wilderness Medical Society Clinical Practice Guidelines on Water Treatment for Wilderness, International Travel, and Austere Situations: 2024 Update

To provide guidance to medical providers, wilderness users, and travelers, the Wilderness Medical Society convened an expert panel to develop evidence-based guidelines for treating water in situations where the potability of available water is not assured, including wilderness and international travel, areas impacted by disaster, and other areas without adequate sanitation. The guidelines present the available methods for reducing or eliminating microbiological contamination of water for individuals, groups, or households; evaluation of their effectiveness; and practical considerations. The evidence base includes both laboratory and clinical publications. The panel graded the recommendations based on the quality of supporting evidence and the balance between benefits and risks/burdens according to the criteria published by the American College of Chest Physicians.

Trapping Halogen Anions in Cationic Viologen Porous Organic Polymers for Highly Cycling-Stable Cathode Materials

Halogens, especially Br2 and I2 , as cathode materials for lithium-ion batteries exhibit high energy density with low cost, but poor cycling performance due to their high solubility in electrolyte solution. Herein, viologen-based cationic porous organic polymers (TpVXs, X = Cl, Br, or I) with abundant pores and ionic redox-active moieties are designed to immobilize halogen anions stoichiometrically. TpVBr and TpVI electrodes exhibit high initial specific capacity (116 and 132 mAh g-1 at 0.2 C) and high average discharge voltage (≈3.0 V) without any host materials. Notably, benefiting from the porous and ionic structure, TpVBr and TpVI present excellent long-term cycling stability (86% and 98% capacity retention after 600 cycles at 0.5 C), which are far superior to those of the state-of-the-art halogen electrodes. In addition, the charge storage mechanism is investigated by in situ Raman and ex situ X-ray photoelectron spectroscopy.

Orally Bioavailable 4-Phenoxy-quinoline Compound as a Potent Aurora Kinase B Relocation Blocker for Cancer Treatment

We investigated a novel 4-phenoxy-quinoline-based scaffold that mislocalizes the essential mitotic kinase, Aurora kinase B (AURKB). Here, we evaluated the impact of halogen substitutions (F, Cl, Br, and I) on this scaffold with respect to various drug parameters. Br-substituted LXY18 was found to be a potent and orally bioavailable disruptor of cell division, at sub-nanomolar concentrations. LXY18 prevents cytokinesis by blocking AURKB relocalization in mitosis and exhibits broad-spectrum antimitotic activity in vitro. With a favorable pharmacokinetic profile, it shows widespread tissue distribution including the blood-brain barrier penetrance and effective accumulation in tumor tissues. More importantly, it markedly suppresses tumor growth. The novel mode of action of LXY18 may eliminate some drawbacks of direct catalytic inhibition of Aurora kinases. Successful development of LXY18 as a clinical candidate for cancer treatment could enable a new, less toxic means of antimitotic attack that avoids drug resistance mechanisms.

Dynamic and Static Nature of XH-∗-π and YX-∗-π (X = F, Cl, Br, and I; Y = X and F) in the Distorted π-System of Corannulene Elucidated with QTAIM Dual Functional Analysis

The dynamic and static nature of the XH-∗-π and YX-∗-π (X = F, Cl, Br, and I; Y = X and F) interactions in the distorted π-system of corannulene (π(C₂₀H₁₀)) is elucidated with a QTAIM dual functional analysis (QTAIM-DFA), where asterisks emphasize the presence of bond critical points (BCPs) on the interactions. The static and dynamic nature originates from the data of the fully optimized and perturbed structures, respectively, in QTAIM-DFA. On the convex side, H in F-H-∗-π(C₂₀H₁₀) and each X in Y-X-∗-π(C₂₀H₁₀) join to C of the central five-membered ring in π(C₂₀H₁₀) through a bond path (BP), while each H in X-H-∗-π(C₂₀H₁₀) does so to the midpoint of C=C in the central five-membered ring for X = Cl, Br, or I. On the concave side, each X in F-X-∗-π(C₂₀H₁₀) also joins to C of the central five-membered ring with a BP for X = H, Cl, Br, and I; however, the interactions in other adducts are more complex than those on the convex side. Both H and X in X-H-∗-π(C₂₀H₁₀) (X = Cl and Br) and both Fs in F-F-∗-π(C₂₀H₁₀) connect to the three C atoms in each central five-membered ring (with three BPs). Two, three, and five BPs were detected for the Cl-Cl, I-H, Br-Br, and I-I adducts, where some BPs do not stay on the central five-membered ring in π(C₂₀H₁₀). The interactions are predicted to have a vdW to CT-MC nature. The interactions on the concave side seem weaker than those on the convex side for X-H-∗-π(C₂₀H₁₀), whereas the inverse trend is observed for Y-X-∗-π(C₂₀H₁₀) as a whole. The nature of the interactions in the π(C₂₀H₁₀) adducts of the convex and concave sides is examined in more detail, employing the adducts with X-H and F-X placed on their molecular axis together with the π(C₂₄H₁₂) and π(C₆H₆) adducts.

New Analytical Strategy for Bioaccessibility Evaluation of Bromine and Iodine from Edible Seaweeds

A strategy for determining the bioaccessibility of bromine and iodine from edible seaweeds was proposed for the first time using microwave-induced combustion (MIC) and ion chromatography coupled to mass spectrometry (IC-MS) after in vitro digestion. The concentrations of bromine and iodine in edible seaweeds using the proposed methods (MIC and IC-MS) were not statistically different from those using MIC and inductively coupled plasma mass spectrometry (p > 0.05). Trueness was assessed by recovery experiments (101-110%, relative standard deviation <10%). Following an in vitro digestion protocol, MIC was proposed as sample preparation for bioaccessible and residual fractions. Using this strategy, the mass balance totaled from 97 to 111%. No statistical difference (p > 0.05) was observed between the total concentration of bromine or iodine and their concentration in bioaccessible and residual fractions for three edible seaweed species, indicating full analyte quantification in the fractions.

Direct C2-H alkylation of indoles driven by the photochemical activity of halogen-bonded complexes

A light-driven metal-free protocol for the synthesis of sulfone-containing indoles under mild conditions is reported. Specifically, the process is driven by the photochemical activity of halogen-bonded complexes formed upon complexation of a sacrificial donor, namely 1,4-diazabicyclo[2.2.2]octane (DABCO), with α-iodosulfones. The reaction provides a variety of densely functionalized products in good yields (up to 96% yield). Mechanistic investigations are reported. These studies provide convincing evidences for the photochemical formation of reactive open-shell species.

Halogen-Based 17β-HSD1 Inhibitors: Insights from DFT, Docking, and Molecular Dynamics Simulation Studies

The high expression of 17β-hydroxysteroid dehydrogenase type 1 (17β-HSD1) mRNA has been found in breast cancer tissues and endometriosis. The current research focuses on preparing a range of organic molecules as 17β-HSD1 inhibitors. Among them, the derivatives of hydroxyphenyl naphthol steroidomimetics are reported as one of the potential groups of inhibitors for treating estrogen-dependent disorders. Looking at the recent trends in drug design, many halogen-based drugs have been approved by the FDA in the last few years. Here, we propose sixteen potential hydroxyphenyl naphthol steroidomimetics-based inhibitors through halogen substitution. Our Frontier Molecular Orbitals (FMO) analysis reveals that the halogen atom significantly lowers the Lowest Unoccupied Molecular Orbital (LUMO) level, and iodine shows an excellent capability to reduce the LUMO in particular. Tri-halogen substitution shows more chemical reactivity via a reduced HOMO-LUMO gap. Furthermore, the computed DFT descriptors highlight the structure-property relationship towards their binding ability to the 17β-HSD1 protein. We analyze the nature of different noncovalent interactions between these molecules and the 17β-HSD1 using molecular docking analysis. The halogen-derived molecules showed binding energy ranging from -10.26 to -11.94 kcal/mol. Furthermore, the molecular dynamics (MD) simulations show that the newly proposed compounds provide good stability with 17β-HSD1. The information obtained from this investigation will advance our knowledge of the 17β-HSD1 inhibitors and offer clues to developing new 17β-HSD1 inhibitors for future applications.

New Halogen-Containing Drugs Approved by FDA in 2021: An Overview on Their Syntheses and Pharmaceutical Use

This review describes the recent Food and Drug Administration (FDA)-approved drugs (in the year 2021) containing at least one halogen atom (covalently bound). The structures proposed throughout this work are grouped according to their therapeutical use. Their synthesis is presented as well. The number of halogenated molecules that are reaching the market is regularly preserved, and 14 of the 50 molecules approved by the FDA in the last year contain halogens. This underlines the emergent role of halogens and, in particular, of fluorine and chlorine in the preparation of drugs for the treatment of several diseases such as viral infections, several types of cancer, cardiovascular disease, multiple sclerosis, migraine and inflammatory diseases such as vasculitis.

After 200 Years: The Structure of Bleach and Characterization of Hypohalite Ions by Single-Crystal X-Ray Diffraction*

We report the first X-ray single crystal structures of hypochlorite (ClO^- ) and hypobromite (BrO^- ) salts, including hydrated sodium hypochlorite, a staple of the chlorine industry and ubiquitous bleaching and disinfection agent for almost 200 years. The structures, supported by variable-temperature Raman spectroscopy on individual crystals and periodic density-functional theory (DFT) calculations, provide insight into solid-state geometry and supramolecular chemistry of hypohalite ions.

Sex differences in cardiopulmonary effects of acute bromine exposure

Accidental occupational bromine (Br>2>) exposures are common, leading to significant morbidity and mortality; however, the specific effects of Br>2> inhalation in female victims are unclear. Our studies demonstrated that acute high-concentration Br>2> inhalation is fatal, and cardiac injury and dysfunction play an important role in Br>2> toxicity in males. In this study, we exposed female Sprague Dawley rats, age-matched to those males from previously studied, to 600 ppm Br>2> for 45 min and assessed their survival, cardiopulmonary injury and cardiac function after exposure. Br>2> exposure caused serious mortality in female rats (59%) 48 h after exposure. Rats had severe clinical distress, reduced heart rates and oxygen saturation after Br>2> inhalation as was previously reported with male animals. There was significant lung injury and edema when measured 24 h after exposure. Cardiac injury biomarkers were also significantly elevated 24 h after Br>2> inhalation. Echocardiography and hemodynamic studies were also performed and revealed that the mean arterial pressure was not significantly elevated in females. Other functional cardiac parameters were also altered. Aside from the lack of elevation of blood pressure, all other changes observed in female animals were also present in male animals as reported in our previous study. These studies are important to understand the toxicity mechanisms to generate therapies and better-equip first responders to deal with these specific scenarios after bromine spill disasters.>.

Recent Strategies for Carbon-Halogen Bond Formation Using Nickel

Nickel catalysis has demonstrated the capability of performing a broad range of synthetically challenging transformations over the last decade. Though recent literature has focused on the formation of C-C and C-N bonds, a variety of breakthroughs in the field of C-X bond generation have also been reported. A diverse range of strategies using nickel have been developed, in an effort to expand the scope and synthetic utility of these halogenation methods. This Minireview will cover six emerging strategies in this field including: oxidatively induced C-X reductive elimination, triflate-to-halogen exchange reactions, directed C-H halogenation, non-directed electrophilic C-H halogenation of arenes, enantioselective α-fluorination of carbonyl containing compounds, and 1,2-difunctionalization-halogenation reactions. The final section has been split into two parts: nickel-catalyzed hydrohalogenation and nickel-catalyzed carbohalogenation reactions.

Behavioral and Neuronal Effects of Inhaled Bromine Gas: Oxidative Brain Stem Damage

The risk of accidental bromine (Br2) exposure to the public has increased due to its enhanced industrial use. Inhaled Br2 damages the lungs and the heart; however, adverse effects on the brain are unknown. In this study, we examined the neurological effects of inhaled Br2 in Sprague Dawley rats. Rats were exposed to Br2 (600 ppm for 45 min) and transferred to room air and cage behavior, and levels of glial fibrillary acidic protein (GFAP) in plasma were examined at various time intervals. Bromine exposure resulted in abnormal cage behavior such as head hitting, biting and aggression, hypervigilance, and hyperactivity. An increase in plasma GFAP and brain 4-hydroxynonenal (4-HNE) content also was observed in the exposed animals. Acute and delayed sympathetic nervous system activation was also evaluated by assessing the expression of catecholamine biosynthesizing enzymes, tryptophan hydroxylase (TrpH1 and TrpH2), and tyrosine hydroxylase (TyrH), along with an assessment of catecholamines and their metabolites. TyrH was found to be increased in a time-dependent manner. TrpH1 and TrpH2 were significantly decreased upon Br2 exposure in the brainstem. The neurotransmitter content evaluation indicated an increase in 5-HT and dopamine at early timepoints after exposure; however, other metabolites were not significantly altered. Taken together, our results predict brain damage and autonomic dysfunction upon Br2 exposure.

Marine iodine emissions in a changing world

Iodine is a critical trace element involved in many diverse and important processes in the Earth system. The importance of iodine for human health has been known for over a century, with low iodine in the diet being linked to goitre, cretinism and neonatal death. Research over the last few decades has shown that iodine has significant impacts on tropospheric photochemistry, ultimately impacting climate by reducing the radiative forcing of ozone (O₃) and air quality by reducing extreme O₃ concentrations in polluted regions. Iodine is naturally present in the ocean, predominantly as aqueous iodide and iodate. The rapid reaction of sea-surface iodide with O₃ is believed to be the largest single source of gaseous iodine to the atmosphere. Due to increased anthropogenic O₃, this release of iodine is believed to have increased dramatically over the twentieth century, by as much as a factor of 3. Uncertainties in the marine iodine distribution and global cycle are, however, major constraints in the effective prediction of how the emissions of iodine and its biogeochemical cycle may change in the future or have changed in the past. Here, we present a synthesis of recent results by our team and others which bring a fresh perspective to understanding the global iodine biogeochemical cycle. In particular, we suggest that future climate-induced oceanographic changes could result in a significant change in aqueous iodide concentrations in the surface ocean, with implications for atmospheric air quality and climate.

The HOX⋯SO2 (X=F, Cl, Br, I) Binary Complexes: Implications for Atmospheric Chemistry

Sulfur dioxide and hypohalous acids (HOX, X=F, Cl, Br, I) are ubiquitous molecules in the atmosphere that are central to important processes like seasonal ozone depletion, acid rain, and cloud nucleation. We present the first theoretical examination of the HOX⋯SO₂ binary complexes and the associated trends due to halogen substitution. Reliable geometries were optimized at the CCSD(T)/aug-cc-pV(T+d)Z level of theory for HOF and HOCl complexes. The HOBr and HOI complexes were optimized at the CCSD(T)/aug-cc-pV(D+d)Z level of theory with the exception of the Br and I atoms which were modeled with an aug-cc-pwCVDZ-PP pseudopotential. 27 HOX⋯SO₂ complexes were characterized and the focal point method was employed to produce CCSDT(Q)/CBS interaction energies. Natural Bond Orbital analysis and Symmetry Adapted Perturbation Theory were used to classify the nature of each principle interaction. The interaction energies of all HOX⋯SO₂ complexes in this study ranged from 1.35 to 3.81 kcal mol^-1 . The single-interaction hydrogen bonded complexes spanned a range of 2.62 to 3.07 kcal mol^-1 , while the single-interaction halogen bonded complexes were far more sensitive to halogen substitution ranging from 1.35 to 3.06 kcal mol^-1 , indicating that the two types of interactions are extremely competitive for heavier halogens. Our results provide insight into the interactions between HOX and SO₂ which may guide further research of related systems.

Cs[Cl3 F10 ]: A Propeller-Shaped [Cl3 F10 ]- Anion in a Peculiar A[5] B[5] Structure Type

Reaction of CsF with ClF3 leads to Cs[Cl3 F10 ]. It contains a molecular, propeller-shaped [Cl3 F10 ]- anion with a central μ3 -F atom and three T-shaped ClF3 molecules coordinated to it. This anion represents the first example of a heteropolyhalide anion of higher ClF3 content than [ClF4 ]- and is the first Cl-containing interhalogen species with a μ-bridging F atom. The chemical bonds to the central μ3 -F atom are highly ionic and quite weak as the bond lengths within the coordinating XF3 units (X = Cl, and also calculated for Br, I) are almost unchanged in comparison to free XF3 molecules. Cs[Cl3 F10 ] crystallizes in a very rarely observed A[5] B[5] structure type, where cations and anions are each pseudohexagonally close packed, and reside, each with coordination number five, in the trigonal bipyramidal voids of the other.

An Improved Electron Microprobe Method for the Analysis of Halogens in Natural Silicate Glasses

We present a new analytical method, which allows the simultaneous analysis of fluorine (F), chlorine (Cl), bromine (Br), and iodine (I) in geological samples. To account for interferences of Fe on the spectral lines of F, of Al on Br-lines, and of Ca on I-lines, we prepared four new halogen-free calibration glasses. The new method is used to analyze various glass reference materials and crystal-hosted melt inclusions from the Azores. Our results show that our new method allows reliable and reproducible analyses of all four halogens in silicate glasses.

The Cl isotope composition and halogen contents of Apollo-return samples

Lunar mare basalts are depleted in F and Cl by approximately an order of magnitude relative to mid-ocean ridge basalts and contain two Cl-bearing components with elevated isotopic compositions relative to the bulk-Earth value of ∼0‰. The first is a water-soluble chloride constituting 65 ± 10% of total Cl with δ³⁷Cl values averaging 3.0 ± 4.3‰. The second is structurally bound chloride with δ³⁷Cl values averaging 7.3 ± 3.5‰. These high and distinctly different isotopic values are inconsistent with equilibrium fractionation processes and instead suggest early and extensive degassing of an isotopically light vapor. No relationship is observed between F/Cl ratios and δ³⁷Cl values, which suggests that lunar halogen depletion largely resulted from the Moon-forming Giant Impact. The δ³⁷Cl values of apatite are generally higher than the structurally bound Cl, and ubiquitously higher than the calculated bulk δ³⁷Cl values of 4.1 ± 4.0‰. The apatite grains are not representative of the bulk rock, and instead record localized degassing during the final stages of lunar magma ocean (LMO) or later melt crystallization. The large variability in the δ³⁷Cl values of apatite within individual thin sections further supports this conclusion. While urKREEP (primeval KREEP [potassium/rare-earth elements/phosphorus]) has been proposed to be the source of the Moon's high Cl isotope values, the ferroan anorthosites (FANs) have the highest δ³⁷Cl values and have a positive correlation with Cl content, and yet do not contain apatite, nor evidence of a KREEP component. The high δ³⁷Cl values in this lithology are explained by the incorporation of a >30‰ HCl vapor from a highly evolved LMO.

Circulating and tissue biomarkers as predictors of bromine gas inhalation

The threat from deliberate or accidental exposure to halogen gases is increasing, as is their industrial applications and use as chemical warfare agents. Biomarkers that can identify halogen exposure, diagnose victims of exposure or predict injury severity, and enable appropriate treatment are lacking. We conducted these studies to determine and validate biomarkers of bromine (Br₂ ) toxicity and correlate the symptoms and the extent of cardiopulmonary injuries. Unanesthetized rats were exposed to Br₂ and monitored noninvasively for clinical scores and pulse oximetry. Animals were euthanized and grouped at various time intervals to assess brominated fatty acid (BFA) content in the plasma, lung, and heart using mass spectrometry. Bronchoalveolar lavage fluid (BALF) protein content was used to assess pulmonary injury. Cardiac troponin I (cTnI) was assessed in the plasma to evaluate cardiac injury. The blood, lung, and cardiac tissue BFA content significantly correlated with the clinical scores, tissue oxygenation, heart rate, and cardiopulmonary injury parameters. Total (free + esterified) bromostearic acid levels correlated with lung injury, as indicated by BALF protein content, and free bromostearic acid levels correlated with plasma cTnI levels. Thus, BFAs and cardiac injury biomarkers can identify Br₂ exposure and predict the severity of organ damage.

New Oxindole-Bridged Acceptors for Organic Sensitizers: Substitution and Performance Studies in Dye-Sensitized Solar Cells

New D-π-A configured organic sensitizers featuring halogen-substituted oxindole-bridged acceptor units have been synthesized for dye-sensitized solar cells applications. Among fluorine, bromine, and iodine substitution, the cell based on bromine incorporated dye exhibited the highest efficiency. The oxindoles in these sensitizers were found to assist the electron injection through the chelation of their amide carbonyl groups to the TiO2 surface. This study provides an alternate approach for future rational dye design to gain excellent DSSC performance.

Upregulation of airway smooth muscle calcium-sensing receptor by low-molecular-weight hyaluronan

We investigated the mechanisms involved in the development of airway hyperresponsiveness (AHR) following exposure of mice to halogens. Male mice (C57BL/6; 20-25 g) exposed to either bromine (Br2) or Cl2 (600 or 400 ppm, respectively, for 30 min) developed AHR 24 h after exposure. Nifedipine (5 mg/kg body wt; an L-type calcium channel blocker), administered subcutaneously after Br2 or Cl2 exposure, produced higher AHR compared with Br2 or Cl2 alone. In contrast, diltiazem (5 mg/kg body wt; a nondihydropyridine L-type calcium channel blocker) decreased AHR to control (air) values. Exposure of immortalized human airway smooth muscle cells (hASMC) to Br2 resulted in membrane potential depolarization (Vm Air: 62 ± 3 mV; 3 h post Br2:-45 ± 5 mV; means ± 1 SE; P < 0.001), increased intracellular [Ca2+]i, and increased expression of the calcium-sensing receptor (Ca-SR) protein. Treatment of hASMC with a siRNA against Ca-SR significantly inhibited the Br2 and nifedipine-induced Vm depolarization and [Ca2+]i increase. Intranasal administration of an antagonist to Ca-SR in mice postexposure to Br2 reversed the effects of Br2 and nifedipine on AHR. Incubation of hASMC with low-molecular-weight hyaluronan (LMW-HA), generated by exposing high-molecular-weight hyaluronan (HMW-HA) to Br2, caused Vm depolarization, [Ca2+]i increase, and Ca-SR expression to a similar extent as exposure to Br2 and Cl2. The addition of HMW-HA to cells or mice exposed to Br2, Cl2, or LMW-HA reversed these effects in vitro and improved AHR in vivo. We conclude that detrimental effects of halogen exposure on AHR are mediated via activation of the Ca-SR by LMW-HA.

Towards a Stronger Halogen Bond Involving Astatine: Unexpected Adduct with Bu3 PO Stabilized by Hydrogen Bonding

The halogen bond is a powerful tool for the molecular design and pushing the limits of its strength is of major interest. Bearing the most potent halogen-bond donor atom, astatine monoiodide (AtI) was recently successfully probed [Nat. Chem. 2018, 10, 428-434]. In this work, we continue the exploration of adducts between AtI and Lewis bases with the tributylphosphine oxide (Bu₃ PO) ligand, revealing the unexpected experimental occurrence of two distinct chemical species with 1:1 and 2:1 stoichiometries. The 1:1 Bu₃ PO⋅⋅⋅AtI complex is found to exhibit the strongest astatine-mediated halogen bond so far (with a formation constant of 10^(4.24±0.35) ). Quantum chemical calculations unveil the intriguing nature of the 2:1 2Bu₃ PO⋅⋅⋅AtI adduct, involving a halogen bond between AtI and one Bu₃ PO molecular unit plus CH⋅⋅⋅O hydrogen bonds chelating the second Bu₃ PO unit.

Halogen-Mediated Partial Oxidation of Polyvinyl Alcohol for Tissue Engineering Purposes

Partial oxidation of polyvinyl alcohol (PVA) with potassium permanganate turned out to be an efficient method to fabricate smart scaffolds for tissue engineering, endowed with biodegradation and protein delivery capacity. This work considered for the first time the use of halogens (bromine, chlorine and iodine) as less aggressive agents than potassium permanganate to perform controlled PVA oxidation, in order to prevent degradation of polymer molecular size upon chemical modification. Oxidized PVA solutions were chemically characterized (i.e., dinitrophenylhydrazine assay, viscosity measurements, molecular size distribution) before preparing physically cross-linked hydrogels. Scaffolds were assessed for their mechanical properties and cell/tissue biocompatibiliy through cytotoxic extract test on IMR-90 fibroblasts and subcutaneous implantation into BALB/c mice. According to chemical investigations, bromine and iodine allowed for minor alteration of polymer molecular weight. Uniaxial tensile tests demonstrated that oxidized scaffolds had decreased mechanical resistance to deformation, suggesting tunable hydrogel stiffness. Finally, oxidized hydrogels exhibited high biocompatibility both in vitro and in vivo, resulting neither to be cytotoxic nor to elicit severe immunitary host reaction in comparison with atoxic PVA. In conclusion, PVA hydrogels oxidized by halogens were successfully fabricated in the effort of adapting polymer characteristics to specific tissue engineering applications.

Wilderness Medical Society Clinical Practice Guidelines for Water Disinfection for Wilderness, International Travel, and Austere Situations

To provide guidance to clinicians, the Wilderness Medical Society convened experts to develop evidence-based guidelines for water disinfection in situations where the potability of available water is not ensured, including wilderness and international travel, areas affected by disaster, and other areas without adequate sanitation. The guidelines present the available methods for reducing or eliminating microbiologic contamination of water for individuals, groups, or households; evaluation of their effectiveness; and practical considerations. The evidence evaluation includes both laboratory and clinical publications. The panel graded the recommendations based on the quality of supporting evidence and the balance between benefits and risks or burdens, according to the criteria published by the American College of Chest Physicians.

Twisting the TAPPs: Bay-Substituted Non-planar Tetraazapero-pyrenes and their Reduced Anions

A new synthesis of tetraazaperopyrenes (TAPPs) starting from a halogenated perylene derivative 3,4,9,10- tetrabromo-1,6,7,12-tetrachloroperylene (1) gave access to bay-substituted TAPPs for the first time. Selective lithiation of the bromine-positions and subsequent addition of tosyl azide led to the formation of the tetraazidotetrachloroperylene (2), which was subsequently reduced by addition of sodium borohydride to the corresponding tetraaminotetrachloroperylene (3). Oxidation to its semiquinoidal form 4 and subsequent cyclization with acid chlorides gave rise to a series of bay-chlorinated TAPPs. Whereas the aromatic core of the previously studied ortho-substituted TAPPs was found to be planar, the steric pressure of the two chlorine substituents on each side leads to the twist of the peropyrene core of approximately 30 degrees, a structural feature also observed in other bay-substituted perylene derivatives. An experimental and computational analysis reveals that introducing chloride substituents at these positions leads to slightly increased electron affinities (EA) enabling the selective generation and characterization of the reduced mono-anionic radicals and closed shell di-anionic species. These anions were isolated and characterized by UV/Vis spectroscopy and EPR or NMR, respectively. Processing of the bay-chlorinated TAPPs in n-channel organic TFTs revealed electron mobilities of 0.001 to 0.003 cm2  V-1  s-1 . These reduced electron mobilities compared to the ortho-halogenated TAPPs are thought to be rooted in the less densely packed solid-state structures.

The shortest chalcogen...halogen contacts in molecular crystals

The survey of the shortest contacts in structures deposited in the Cambridge Structural Database shows that chalcogen...halogen, halogen...halogen and chalcogen...chalcogen interactions can compete as cohesion forces in molecular crystals. The smallest parameter δ (defined as the interatomic distance minus the sum of relevant van der Waals radii) for Ch...X contacts between chalcogens (Ch: S, Se) and halogens (X: F, Cl, Br, I) is present only in 0.86% out of 30 766 deposited structures containing these atoms. Thus, in less than 1% of these structures can the Ch...X forces be considered as the main type of cohesion forces responsible for the molecular arrangement. Among the 263 structures with the shortest Ch...X contact, there are four crystals where no contacts shorter than the sums of van der Waals radii are present (so-called loose crystals). The smallest δ criterion has been used for distinguishing between the bonding (covalent bond) and non-bonding contacts and for validating the structural models of crystals.

Hexahalodiborate Dianions: A New Family of Binary Boron Halides

The electron‐precise binary boron subhalide species [B₂X₆]²⁻ X=F, Br, I) were synthesized and their structures confirmed by X‐ray crystallography. The existence of the previously claimed [B₂Cl₆]²⁻, which had been questioned, was also confirmed by X‐ray crystallography. The dianions are isoelectronic to hexahaloethanes, are subhalide analogues of the well‐known tetrahaloborate anions (BX₄⁻), and are rare examples of molecular electron‐precise binary boron species beyond B₂X₄, BX₃, and [BX₄]⁻.

Rational Synthesis, Structures and Properties of the Ionic Liquid Binary Iodine-Bromine Octahalide Series [In Br8-n ]2- (n=0, 2, 3, 4)

A series of octanuclear iodine-bromine interhalides [I_n Br_8-n ]^2- (n=0, 2, 3, 4) were prepared systematically in two steps. Firstly, addition of a dihalogen (Br₂ or IBr) to the triaminocyclopropenium bromide salt [C₃ (NEt₂ )₃ ]Br forms the corresponding trihalide salt with Br₃ ^- or IBr₂ ^- anions, respectively. Secondly, addition to Br₃ ^- of half an equivalent of Br₂ gives the octabromine polyhalide [Br₈ ]^2- , whereas addition to IBr₂ ^- of half an equivalent of Br₂ , IBr or I₂ gives the corresponding interhalides: [I₂ Br₆ ]^2- , [I₃ Br₅ ]^2- , and [I₄ Br₄ ]^2- , respectively. The four octahalides were characterized by X-ray crystallography, computational studies, Raman and Far-IR spectroscopies, as well as by TGA and melting point. All of the salts were found to be ionic liquids.

A Single Atom Change Facilitates the Membrane Transport of Green Fluorescent Proteins in Mammalian Cells

Direct delivery of proteins into mammalian cells is a challenging problem in biological and biomedical applications. The most common strategies for the delivery of proteins into the cells include the use of cell-penetrating peptides or supercharged proteins. Herein, we show for the first time that a single atom change, hydrogen to halogen, at one of the tyrosine residues can increase the cellular entry of ∼28 kDa green fluorescent protein (GFP) in mammalian cells. The protein uptake is facilitated by a receptor-mediated endocytosis and the cargo can be released effectively into cytosol by co-treatment with the endosomolytic peptide ppTG21.

Recycled Components in Mantle Plumes Deduced From Variations in Halogens (Cl, Br, and I), Trace Elements, and 3He/4He Along the Hawaiian-Emperor Seamount Chain

Halogens are primarily located within surface reservoirs of the Earth; as such they have proven to be effective tracers for the identification of subducted volatiles within the mantle. Subducting lithologies exhibit a wide variety of halogen compositions, yet the mantle maintains a fairly uniform signature, suggesting halogens may be homogenized during subduction to the mantle or during eruption. Here we present halogen (Cl, Br, and I), K, noble gas, and major and trace element data on olivines from three seamounts along the Hawaiian-Emperor seamount chain to determine if the deep mantle source has retained evidence of halogen heterogeneities introduced through subduction. High Ni contents indicate that the Hawaiian-Emperor mantle source contains a recycled oceanic crust component in the form of pyroxenite, which increases from the 46% in the oldest (Detroit) to 70% in the younger seamount (Koko). Detroit seamount retains mid-ocean ridge basalts (MORB)-like Br/Cl and I/Cl, while the Br/Cl and I/Cl of Suiko and Koko seamounts are higher than MORB and similar to altered oceanic crust and dehydrated serpentinite. Helium isotopes show a similar evolution, from MORB-like values at Detroit seamount toward higher values at Suiko and Koko seamounts. The correlation between pyroxenite contributions, Br/Cl, I/Cl, and 3He/4He indicates that subducted material has been incorporated into the primordial undegassed Hawaiian mantle plume source. The identification of recycled oceanic crustal signatures in both the trace elements and halogens indicates that subduction and dehydration of altered oceanic crust may exert control on the cycling of volatile elements to the deep mantle.

Halogen Substituents in the Isoquinoline Scaffold Switches the Selectivity of Inhibition between USP2 and USP7

Deubiquitinases are important components of the protein regulatory network and, hence, constitute a tempting drug target. We report herein structure-activity relationship studies to develop halogen-substituted isoquionoline-1,3-dione-based inhibitors of the deubiquitinase USP2. In contrast to our previous reports, the best compound discovered was found to act through a reactive oxygen species independent, uncompetitive mechanism with an IC₅₀ of 250 nm. We show the crucial role of halogens in the common scaffold to provide potency and selectivity of our compound, where the introduction of the fluorine atom completely switches the selectivity of the inhibitor between USP2 and USP7. Our cellular studies highlight the potential applicability of the reported compound for in vivo experiments. The discovery of the isoquinoline-1,3-dione core and the knowledge obtained with regard to halogen substituents provide a platform towards understanding USP2 inhibition and the development of highly selective next-generation deubiquitinase inhibitors.

C-Halogenated 9,10-Diboraanthracenes: How the Halogen Load and Distribution Influences Key Optoelectronic Properties

9,10-Dihydro-9,10-diboraanthracenes (DBAs) have low-energy LUMOs and narrow HOMO-LUMO gaps and are thus attractive electron-transporting and light-emitting materials in optoelectronic devices. A systematic series of ten C-halogenated 9,10-(Mes)₂ -DBAs was synthesized and studied by cyclic voltammetry, UV/Vis absorption and emission spectroscopy, and quantum-chemical calculations (Mes=mesityl). We probed the influence of the nature of the halogen atoms and the halogen substitution patterns on key optoelectronic properties of the DBAs. All 9,10-(Mes)₂ derivatives can be reversibly reduced at the DBA cores and at electrode potentials between E_1/2 ^Red1 =-1.84 and -1.26 V (vs. FcH/FcH⁺ ). The most bathochromic UV/Vis absorption and the fluorescence emission of each DBA correspond to an ICT transition between the Mes rings and the DBA core. Br substituents lower the DBA LUMO energy and narrow the energy gap to the highest degree along the series F<Cl<Br. Halogen atoms located at 1,4,5,8-positions are more influential than those at 2,3,6,7-positions. An increasing fluorine load continuously decreases the LUMO levels and HOMO-LUMO gaps. Colorless octafluoro- and tetrafluoro-DBAs form colored and fluorescent π-stacked hetero dimers with anthracene in C₆ H₆ solutions and in the solid state. The sterically congested 1,5-(ThMe)₂ -9,10-(Mes)₂ -DBA was prepared in 74 % yield from 1,5-(Br)₂ -9,10-(Mes)₂ -DBA and Me₃ Sn-ThMe through a Stille-type C-C coupling reaction (ThMe=5-Me-2-thienyl).

Improvement of the Photophysical Performance of Platinum-Cyclometalated Complexes in Halogen-Bonded Adducts

Three groups of luminescent platinum complexes [Pt(C^N)(L)(Y)] [C^N=benzothienyl-pyridine (1), bezofuryl-pyridine (2), phenyl-pyridine (3); L/Y=DMSO/Cl (a), PPh₃ /Cl (b), PPh₃ /CN (c)] have been probed as halogen-bond (XB) acceptors towards iodofluorobenzenes (IC₆ F₅ and I₂ C₆ F₄ ). Compounds 1 a and 2 a (L/Y=DMSO/Cl) afford the adducts 1 a⋅⋅⋅I₂ C₆ F₄ and 2 a⋅⋅⋅I₂ C₆ F₄ , which feature I⋅⋅⋅S_btpy /I⋅⋅⋅π_btpy and I⋅⋅⋅O_DMSO /I⋅⋅⋅Cl short contacts, respectively. The phosphane-cyanide derivatives 1 c and 2 c (L/Y=PPh₃ /CN) co-crystallise with both IC₆ F₅ and I₂ C₆ F₄ . None of the phpy-based species 3 a-3 c participated in XB interactions. Although the native complexes are rather poor luminophores in the solid state (Φ_em =0.023-0.089), the adducts exhibit an up to 10-fold increase of the intensity with a minor alteration of the emission energy. The observed gain in the quantum efficiency is mainly attributed to the joint influence of non-covalent interactions (halogen/hydrogen bonding, π-π stacking), which govern the crystal-packing mode and diminish the radiationless pathways for the T₁ →S₀ transition by providing a rigid environment around the chromophore.

Investigation of Large Polychloride Anions: [Cl11 ]- , [Cl12 ]2- , and [Cl13 ]. Angew Chem Int Ed Engl 2018;57:9136-9140. [PMID: 29737601 DOI: 10.1002/anie.201803486]

For decades the chemistry of polyhalides was dominated by polyiodides and more recently also by an increasing number of polybromides. However, apart from a few structures containing trichloride anions and a single report on an octachloride dianion, [Cl₈ ]^2- , polychlorine compounds such as polychloride anions are unknown. Herein, we report on the synthesis and investigation of large polychloride monoanions such as [Cl₁₁ ]^- found in [AsPh₄ ][Cl₁₁ ], [PPh₄ ][Cl₁₁ ], and [PNP][Cl₁₁ ]⋅Cl₂ , and [Cl₁₃ ]^- obtained in [PNP][Cl₁₃ ]. The polychloride dianion [Cl₁₂ ]^2- has been obtained in [NMe₃ Ph]₂ [Cl₁₂ ]. The novel compounds have been thoroughly characterized by NMR spectroscopy, single-crystal Raman spectroscopy, and single-crystal X-ray diffraction. The assignment of their spectra is supported by molecular and periodic solid-state quantum-chemical calculations.

Selective F or Br Functionalization of Dibenzofuran for Application as Host Materials of Phosphorescent Organic Light-Emitting Diodes

Four dibenzofuran-type host materials substituted with a carbazolylcarbazole moiety were synthesized to investigate the effect of substitution position on the material parameters and device performances of host materials. The carbazolylcarbazole moiety was substituted at the 1-, 2-, 3-, and 4-positions of dibenzofuran by F or Br for a comprehensive study of the positional effect of dibenzofuran-derived host materials. Systematic synthesis and comparison of the four host materials revealed that 1-, 2-, and 4-position modification was better than 3-position modification for high triplet energy and high external quantum efficiency.

Hydrogen Bond versus Halogen Bond in Cation-Cation Complexes: Effect of the Solvent

Competition between hydrogen- (HB) and halogen-bonded (XB) 4-ammoniumpyridine and halogenammonium (NH_n F_3-n X⁺ ; n=0-3; X=F, Cl, Br, and I) cation-cation complexes are explored by means of DFT calculations. HB and XB minima structures are found for all systems in the gas phase. As the number of fluorine atoms increases, the HB complexes are more favored than those of XB. Proton transfer is generally observed in complexes with two, three, or four halogen atoms. The XB complexes evolve from traditional halogen bonds, to halogen-shared complexes, and to ionic complexes as the number of fluorine atoms increases. The dissociation transition states and their corresponding barriers are also characterized; the barriers increase as the number of fluorine atoms increases. The results if solvent effects are considered indicate that, even in an apolar solvent, such as n-hexane, most of the complexes have favorable binding energies. Atoms-in-molecules theory is used to analyze the complexes, and results in good correlations between electron density and total electron energy density (Η) values with the intermolecular bond length. According to the Η values obtained, the covalency of these interactions starts to manifest at distances around 72-74 % the sum of the van der Waals radii of the interacting atoms.

Synthesis of Functional Bis(pentafluoroethyl)silanes (C2 F5 )2 SiX2 , with X=H, F, Cl, Br, OPh, and O2 CCF3

As recently shown, the introduction of pentafluoroethyl functionalities into silicon compounds is of general interest due to an enhanced Lewis acidity of the resulting species. By this means, the synthesis of previously inaccessible hypervalent silicon derivatives is enabled. While an easy access to tris(pentafluoroethyl)silanes has already been published, synthetic strategies for the selective preparation of bis derivatives are yet unknown. In this contribution, a convenient protocol for the synthesis of functional bis(pentafluoroethyl)silicon compounds is presented. These compounds represent precursors for the synthesis of pentafluoroethylated polysiloxanes. Furthermore, they prove to be resistant to oxonium cations, which is a key feature for the preparation of stable pentafluoroethylsilic acids. Treatment of dichlorodiphenoxysilane with in situ generated pentafluoroethyl lithium leads to the corresponding bis(pentafluoroethyl)silane in high yields. (C₂ F₅ )₂ Si(OPh)₂ serves as a starting material for further functionalized bis(pentafluoroethyl)silanes. These silanes have been isolated and their reactivity towards N bases studied. The pronounced Lewis acidity of the obtained compounds has been documented by the formation of octahedral adducts with nitrogen donors such as 1,10-phenanthroline and acetonitrile.

Supramolecular Spangling, Crocheting, and Knitting of Functionalized Pyrene Molecules on a Silver Surface

Pyrenes, as photoactive polycyclic aromatic hydrocarbons (PAHs), represent promising modules for the bottom-up assembly of functional nanostructures. Here, we introduce the synthesis of a family of pyrene derivatives peripherally functionalized with pyridin-4-ylethynyl termini and comprehensively characterize their self-assembly abilities on a smooth Ag(111) support by scanning tunneling microscopy. By deliberate selection of number and geometric positioning of the pyridyl-terminated substituents, two-dimensional arrays, one-dimensional coordination chains, and chiral, porous kagomé-type networks can be tailored. A comparison to phenyl-functionalized reference pyrenes, not supporting the self-assembly of ordered structures at low coverage, highlights the role of the pyridyl moieties for supramolecular crocheting and knitting. Furthermore, we demonstrate the selective spangling of pores in the two-dimensional pyrene assemblies by a distinct number of iodine atoms as guests by atomically resolved imaging and complementary X-ray photoelectron spectroscopy.

Behavior of Halogen Bonds of the Y-X⋅⋅⋅π Type (X, Y=F, Cl, Br, I) in the Benzene π System, Elucidated by Using a Quantum Theory of Atoms in Molecules Dual-Functional Analysis

The nature of halogen bonds of the Y-X-✶-π(C6 H6 ) type (X, Y=F, Cl, Br, and I) have been elucidated by using the quantum theory of atoms in molecules (QTAIM) dual-functional analysis (QTAIM-DFA), which we proposed recently. Asterisks (✶) emphasize the presence of bond-critical points (BCPs) in the interactions in question. Total electron energy densities, Hb (rc ), are plotted versus Hb (rc )-Vb (rc )/2 [=(ħ(2) /8m)∇(2) ρb (rc )] for the interactions in QTAIM-DFA, in which Vb (rc ) are potential energy densities at the BCPs. Data for perturbed structures around fully optimized structures were used for the plots, in addition to those of the fully optimized ones. The plots were analyzed by using the polar (R, θ) coordinate for the data of fully optimized structures with (θp , κp ) for those that contained the perturbed structures; θp corresponds to the tangent line of the plot and κp is the curvature. Whereas (R, θ) corresponds to the static nature, (θp , κp ) represents the dynamic nature of the interactions. All interactions in Y-X-✶-π(C6 H6 ) are classified by pure closed-shell interactions and characterized to have vdW nature, except for Y-I-✶-π(C6 H6 ) (Y=F, Cl, Br) and F-Br-✶-π(C6 H6 ), which have typical hydrogen-bond nature without covalency. I-I-✶-π(C6 H6 ) has a borderline nature between the two. Y-F-✶-π(C6 H6 ) (Y=Br, I) were optimized as bent forms, in which Y-✶-π interactions were detected. The Y-✶-π interactions in the bent forms are predicted to be substantially weaker than those in the linear F-Y-✶-π(C6 H6 ) forms.

Structures of Trichloromethyl Thiocyanate, CCl3 SCN, in Gaseous and Crystalline State

Trichloromethyl thiocyanate, CCl3 SCN, was structurally studied in both the gas and crystal phases by means of gas electron diffraction (GED) and single-crystal X-ray diffraction (XRD), respectively. Both experimental studies and quantum chemical calculations indicate a staggered orientation of the CCl3 group relative to the SCN group. This conclusion is supported by the similarity of the C-SCN bond length to that of the anti-structure of CH2 ClSCN (Berrueta Martínez et al. Phys. Chem. Chem. Phys. 2015, 17, 15805-15812). Bond lengths and angles are similar for gas and crystal CCl3 SCN structures; however, the crystal structure presents different intermolecular interactions. These include halogen and chalcogen type interactions, the geometry of which was studied. Characteristic C-Y⋅⋅⋅N angles (Y=Cl or S) close to 180° provide evidence for typical σ-hole interactions along the halogen/chalcogen-carbon bond in N⋅⋅⋅Cl and N⋅⋅⋅S, intermolecular units.

Building a Better Halide Receptor: Optimum Choice of Spacer, Binding Unit, and Halosubstitution

Quantum calculations are used to measure the binding of halides to a number of bipodal dicationic receptors, constructed as a pair of binding units separated by a spacer group. A number of variations are studied. A H atom on each binding unit (imidazolium or triazolium) is replaced by Br or I. Benzene, thiophene, carbazole, and dimethylnaphthalene are considered as spacer groups. Each receptor is paired with halides F(-) , Cl(-) , Br(-) , and I(-) . Substitution with I on the binding unit yields a large enhancement of binding, as much as 13 orders of magnitude; a much smaller increase occurs for substitution with Br. Imidazolium is a more effective binding agent than is triazolium. Benzene and dimethylnaphthalene represent the best spacers, followed by thiophene and carbazole. F(-) binds much more strongly than do the other halides, which obey the order Cl(-) >Br(-) >I(-) .

Synthesis of the Stable Ordered Conjugated Polymer Poly(dibromodiacetylene) from an Explosive Monomer

Dibromobutadiyne is an extremely unstable compound that explodes at room temperature, even under inert atmosphere. This instability has limited the studies of dibromobutadiyne almost entirely to spectroscopic characterization. Here we report an approach to control the reactivity of dibromobutadiyne, via topochemical reaction in cocrystals, leading to the ordered polymer poly(dibromodiacetylene), PBDA. At low temperatures (-15 to -18 °C), dibromobutadiyne can form cocrystals with oxalamide host molecules containing either pyridyl or nitrile side groups, in which halogen bonds align the dibromobutadiyne monomers for topochemical polymerization. The cocrystals with the bis(nitrile) oxalamide host undergo complete ordered polymerization to PBDA, demonstrated by solid-state MAS-NMR, Raman, and optical absorption spectroscopy. Once formed, the polymer can be separated from the host; unlike the monomer, PBDA is stable at room temperature.

Inhaled matters of the heart

Inhalations of atmospheric pollutants, especially particulate matters, are known to cause severe cardiac effects and to exacerbate preexisting heart disease. Heart failure is an important sequellae of gaseous inhalation such as that of carbon monoxide. Similarly, other gases such as sulphur dioxide are known to cause detrimental cardiovascular events. However, mechanisms of these cardiac toxicities are so far unknown. Increased susceptibility of the heart to oxidative stress may play a role. Low levels of antioxidants in the heart as compared to other organs and high levels of reactive oxygen species produced due to the high energetic demand and metabolic rate in cardiac muscle are important in rendering this susceptibility. Acute inhalation of high concentrations of halogen gases is often fatal. Severe respiratory injury and distress occurs upon inhalation of halogens gases, such as chlorine and bromine; however, studies on their cardiac effects are scant. We have demonstrated that inhalation of high concentrations of halogen gases cause significant cardiac injury, dysfunction, and failure that can be critical in causing mortalities following exposures. Our studies also demonstrated that cardiac dysfunction occurs as a result of a direct insult independent of coexisting hypoxia, since it is not fully reversed by oxygen supplementation. Therefore, studies on offsite organ effects of inhaled toxic gases can impact development of treatment strategies upon accidental or deliberate exposures to these agents. Here we summarize the knowledge of cardiovascular effects of common inhaled toxic gases with the intent to highlight the importance of consideration of cardiac symptoms while treating the victims.

Active and widespread halogen chemistry in the tropical and subtropical free troposphere

Halogens in the troposphere are increasingly recognized as playing an important role for atmospheric chemistry, and possibly climate. Bromine and iodine react catalytically to destroy ozone (O3), oxidize mercury, and modify oxidative capacity that is relevant for the lifetime of greenhouse gases. Most of the tropospheric O3 and methane (CH4) loss occurs at tropical latitudes. Here we report simultaneous measurements of vertical profiles of bromine oxide (BrO) and iodine oxide (IO) in the tropical and subtropical free troposphere (10 °N to 40 °S), and show that these halogens are responsible for 34% of the column-integrated loss of tropospheric O3. The observed BrO concentrations increase strongly with altitude (∼ 3.4 pptv at 13.5 km), and are 2-4 times higher than predicted in the tropical free troposphere. BrO resembles model predictions more closely in stratospheric air. The largest model low bias is observed in the lower tropical transition layer (TTL) over the tropical eastern Pacific Ocean, and may reflect a missing inorganic bromine source supplying an additional 2.5-6.4 pptv total inorganic bromine (Bry), or model overestimated Bry wet scavenging. Our results highlight the importance of heterogeneous chemistry on ice clouds, and imply an additional Bry source from the debromination of sea salt residue in the lower TTL. The observed levels of bromine oxidize mercury up to 3.5 times faster than models predict, possibly increasing mercury deposition to the ocean. The halogen-catalyzed loss of tropospheric O3 needs to be considered when estimating past and future ozone radiative effects.

Halogenotrinitromethanes: a combined study in the crystalline and gaseous phase and using quantum chemical methods

The halogenotrinitromethanes FC(NO2 )3 (1), BrC(NO2 )3 (2), and IC(NO2)3 (3) were synthesized and fully characterized. The molecular structures of 1-3 were determined in the crystalline state by X-ray diffraction, and gas-phase structures of 1 and 2 were determined by electron diffraction. The Hal-C bond lengths in F-, Cl-, and Br-C(NO2 )3 in the crystalline state are similar to those in the gas phase. The obtained experimental data are interpreted in terms of Natural Bond Orbitals (NBO), Atoms in Molecules (AIM), and Interacting Quantum Atoms (IQA) theories. All halogenotrinitromethanes show various intra- and intermolecular non-bonded interactions. Intramolecular N⋅⋅⋅O and Hal⋅⋅⋅O (Hal=F (1), Br (2), I (3)) interactions, both competitors in terms of the orientation of the nitro groups by rotation about the C-N bonds, lead to a propeller-type twisting of these groups favoring the mentioned interactions. The origin of the unusually short Hal-C bonds is discussed in detail. The results of this study are compared to the molecular structure of ClC(NO2 )3 and the respective interactions therein.

Borylation of unactivated aryl chlorides under mild conditions by using diisopropylaminoborane as a borylating reagent

The synthesis of arylboronic ester derivatives from aryl chlorides by using aryl(amino)boranes is described. Palladium-catalyzed coupling between aryl chlorides and diisopropylaminoborane leads to the formation of a CB bond under mild conditions. A wide range of functional groups are tolerated, making this method particularly useful for the borylation of functionalized aromatics.

How much binding affinity can be gained by filling a cavity?

Binding affinity optimization is critical during drug development. Here, we evaluate the thermodynamic consequences of filling a binding cavity with functionalities of increasing van der Waals radii (-H, -F, -Cl, and CH(3)) that improve the geometric fit without participating in hydrogen bonding or other specific interactions. We observe a binding affinity increase of two orders of magnitude. There appears to be three phases in the process. The first phase is associated with the formation of stable van der Waals interactions. This phase is characterized by a gain in binding enthalpy and a loss in binding entropy, attributed to a loss of conformational degrees of freedom. For the specific case presented in this article, the enthalpy gain amounts to -1.5 kcal/mol while the entropic losses amount to +0.9 kcal/mol resulting in a net 3.5-fold affinity gain. The second phase is characterized by simultaneous enthalpic and entropic gains. This phase improves the binding affinity 25-fold. The third phase represents the collapse of the trend and is triggered by the introduction of chemical functionalities larger than the binding cavity itself [CH(CH(3))(2)]. It is characterized by large enthalpy and affinity losses. The thermodynamic signatures associated with each phase provide guidelines for lead optimization.

Toxicity of halogenated oxyquinolines in dogs. A clinical study. I. A survey of cases

A survey of 100 cases of oxyquinoline poisoning in dogs is presented. The disease, characterized by hyperexcitability of the CNS with convulsions as well as heart and liver injury, runs an acute course. The mortality (euthanized dogs included) was 30 %. Case-history data showed that the oxyquinoline treatment which preceded the disease was given because the dog had incidental diarrhoea. In most cases the drugs were administered for only 1 day before the dog fell ill. The median time from the last dose to onset of symptoms was 12 hrs. Old dogs were affected more often than expected and also showed higher mortality than did young dogs.