Influence Of Halogens Research Articles

Abstract 4165: Influence of halogens in squaraine dye on optoacoustic signal

Abstract Optoacoustic imaging has grown in clinical relevance due to inherent advantages in sensitivity, resolution, and contrast, compared to standard modalities, such as fluorescence. However, guiding principles for development of small molecule contrast agents specific for optoacoustic imaging is lacking. This study assesses the influence of specific structural features of small molecule dyes, specifically squaraine dyes, that result in optoacoustic activity. Through computational models, in vitro testing, and in vivo experimentation this study assesses the effects of halogens on small molecule squaraine dyes to increase optoacoustic signal. By using the aid of our computational model, we decorated the squaraine scaffold with heavy halogenation of squaraines increased optoacoustic activity (2.12 a.u. vs. 0.21 a.u., p<0.001). Density functional theory models suggest the origin of increased optoacoustic signal is due to increases in transition dipole moment which manifested experimentally as increased absorbance in the NIR wavelength range and decreased fluorescence quantum yield, respectively. This study provides an insight into the structure-function relationships that lead to guiding principles for designing optoacoustic-specific contrast agents. Further developments of squaraines and other types of optoacoustic agents will further increase relevance of optoacoustic imaging in a clinical setting. Citation Format: Kavita Belligund, William MacCuaig, Carly Wickizer, Yihan Shao, Lacey R. McNally. Influence of halogens in squaraine dye on optoacoustic signal [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4165.

Halogens Enhance Haze Pollution in China.

Severe and persistent haze events in northern China, characterized by high loading of fine aerosol especially of secondary origin, negatively impact human health and the welfare of ecosystems. However, current knowledge cannot fully explain the formation of this haze pollution. Despite field observations of elevated levels of reactive halogen species (e.g., BrCl, ClNO2, Cl2, HBr) at several sites in China, the influence of halogens (particularly bromine) on haze pollution is largely unknown. Here, for the first time, we compile an emission inventory of anthropogenic bromine and quantify the collective impact of halogens on haze pollution in northern China. We utilize a regional model (WRF-Chem), revised to incorporate updated halogen chemistry and anthropogenic chlorine and bromine emissions and validated by measurements of atmospheric pollutants and halogens, to show that halogens enhance the loading of fine aerosol in northern China (on average by 21%) and especially its secondary components (∼130% for secondary organic aerosol and ∼20% for sulfate, nitrate, and ammonium aerosols). Such a significant increase is attributed to the enhancement of atmospheric oxidants (OH, HO2, O3, NO3, Cl, and Br) by halogen chemistry, with a significant contribution from previously unconsidered bromine. These results show that higher recognition of the impact of anthropogenic halogens shall be given in haze pollution research and air quality regulation.

The Perlin effect in 2-halocyclohexanones and 2-halocyclohexanethiones

The Perlin effect is an NMR phenomenon observed in six-membered rings and it is referred to as 1JC−Hax < 1JC−Heq. In the present work, the influence of halogens (F, Cl and Br) at position 2 in cyclohexanones and cyclohexanethiones is theoretically evaluated on the one-bond C2H2 coupling constants, i.e. on the Perlin effect. An important hyperconjugative interaction (πC=Y → σ*C-H, Y = O and S) operating in the studied systems seems to play a significant role for the observed 1JC−Hax < 1JC−Heq behavior. In addition, the Lewis contribution (JLewis) dominates the Fermi Contact term (JFC), which plays the major role for the overall one-bond CH coupling constant. Compared to the gas phase, this behavior was found to be insensitive to implicit solvents (DMSO and water).

Photoluminescent nickel(II)-metallomesogens derived from salphen ligands: influence of halogens at the spacer on mesomorphism and emission properties

ABSTRACTThree new series of photoluminescent nickel(II) metallomesogens, [NiL]; H2L = N,N′-Bis(4-n-alkoxysalicylidene)-4-fluoro/bromo/chloro-1,2-diaminobenzene (n = 12, 14, 16) based on ‘salphen’ ligands have been synthesised and their mesomorphic and photophysical properties explored. The complexes, isolated as orange microcrystalline solids were characterised by elemental analyses, FT-IR, 1H NMR and UV-visible spectroscopy. Thermal studies show all the compounds to be enantiotropic liquid crystals displaying columnar mesophase over a wide temperature range. Electronegativity and steric requirement of the halogen substituent at the ligand’s spacer remarkably influence the 2-D packing of the columns in the lattice in these complexes controlling the supramolecular mesomorphic order and photoluminescence. The mesophase behaviour of the fluoro-substituted complex is characterised by a transition from a columnar oblique (p1) to columnar rectangular (p2mm) phase, former stable till ambient temperature. The chloro and bromo analogues, on the other hand, displayed exclusively columnar rectangular (p2mm) mesophase with the former transforming into a glassy state and latter into a crystalline phase during cooling to ambient temperature. Molecular model based on interdigitated anti-parallel and back to back arrangements in the different columnar mesophase are proposed on the basis of X-ray diffraction (XRD) studies. The complexes emit in the blue region when excited with near UV wavelength.

Textures and high field strength elements in hydrothermal magnetite from a skarn system: Implications for coupled dissolution-reprecipitation reactions

There is increasing evidence to suggest that high field strength elements (HFSE) could be mobile to some extent in hydrothermal fluid due to the influence of halogens (e.g., fluorine and chlorine). However, in natural hydrothermal (fluid) systems, “coupled dissolution reprecipitation” (CDR) reactions at fluid-mineral interfaces that have been emphasized in the past decade may play a key role in controlling the final textures and mineral assemblages. The influences of the CDR reactions in hydrothermal systems on HFSE enrichment or depletion at the mineral scale are enigmatic. In this study, we show that enrichment of Nb and Zr can occur in magnetite on the mineral scale formed by hydrothermal fluids at medium-to-lower temperature in a skarn system. Four stages of mineralization and alteration of magnetite have been identified in the Baishiya iron skarn deposit of the East Kunlun Mountains of China. Magnetite formed in stage 1 (S1) developed obvious oscillatory zonation, whereas that formed in stages 2 (S2) and 3 (S3) shows hydrothermal alteration and metasomatic textures, and that in stage 4 (S4) developed euhedral crystals with simple zoning. Systematic variations in the trace element compositions of different magnetite grains analyzed by EMPA and LA-ICP-MS suggest that the magnetite from S1 to S3 may have formed in a metasomatic process at relatively constant temperature, whereas the magnetite from S4 formed by re-equilibrium processes at lower temperature. The magnetite from each stage can be divided into light and dark domains based on backscattered electron images. The dark domains in the magnetite from S1 and S2 have higher Nb/Ta (8.52–27.00) and Zr/Hf (18.22–52.64) ratios and silicon contents than the light domains (0.55–5.66 and 2.54–16.43, respectively). Compared with other magnetite ores, the ores from S1 and S2 are depleted of V and Ni. This depletion may be induced by increased oxygen and co-crystallized sulfide. However, these variations are unlikely to be responsible for the enrichment of Nb and Zr in magnetite at equilibrium conditions. Conversely, the dark domains of the magnetite from S1 and S2 are porous, irregular, and/or oscillatory with quartz inclusions, indicating nonequilibrium conditions. These textural features could be attributed to the CDR reactions that are ubiquitous in skarn systems. The increased silicon concentrations in magnetite due to the CDR reactions could affect the lattice parameters of the magnetite structure, leading to an overall change in the volume of magnetite ores. The reduplicative processes of volume change, dissolution, and porosity formation within magnetite are further imporved due to an incresed oxygen fugacity and co-crystallized sulfide (e.g., decreased temperature or increased sulfur fugacity) at far-from-equilibrium or local equilibrium conditions, resulting in oscillatory magnetite dark domains of S1. Ripening of the transient porosity can trap nanoscale precipitates of columbite and zircon within pores of Si-magnetite, and this precipitation could be attributed to the co-crystallized phlogopite that would incorporate fluorine from the hydrothermal fluid, and subsequently decrease the solubility of Nb and Zr in the skarn system. This scenario highlights that Nb and Zr could be scavenged and enriched into in the reaction fronts (porosity) by controlling the reaction pathway at a local scale that does not reflect the overall fluid-rock interaction history of the mineral assemblage.

The Synergetic Interplay of Weak Interactions in the Ion‐Pair Recognition of Quaternary and Diquaternary Ammonium Salts by Halogenated Resorcinarenes

AbstractThe influence of halogens on the noncovalent interactions of different upper‐rim‐substituted hexylresorcinarenes with quaternary and diquaternary ammonium iodide salts was investigated in the gas phase by electrospray ionization Fourier‐transform ion‐cyclotron‐resonance (ESI‐FTICR) mass spectrometry and in solution by 1H NMR titration studies. The electronic nature of the substituents on the upper rim of the resorcinarene was directly reflected in the order of binding strengths of the hosts towards quaternary and diquaternary ammonium cations in the gas phase. In solution, the opposite trend was observed, with generally higher binding constants for the diquaternary over the quaternary salts. This phenomenon is explained by the synergetic effect originating from the interaction of the halogenated resorcinarenes with the counteranions through enhanced hydrogen bonding, leading to ion‐pair binding in solution. The electronegativity of the halogens renders the hydrogen of the hydroxy group more acidic, and hence enforces hydrogen bonding in solution. The collective effect of several weak interactions is manifested in solution, thereby emphasizing the benefits of comparing solution and gas‐phase studies in recognition processes.

How relevant is the deposition of mercury onto snowpacks? – Part 1: A statistical study on the impact of environmental factors

Abstract. A portion of the highly toxic methylmercury that bioaccumulates in aquatic life is created from mercury entering bodies of water with snowpack meltwater. To determine the importance of meltwater as a source of aquatic mercury, it is necessary to understand the environmental processes that govern the behavior of snowpack-related mercury. In this study we investigate relationships among 5 types of snowpack-related mercury observations and 20 model environmental variables. The observation types are the 24-h fractional loss of mercury from surface snow, and the concentrations of mercury in surface snow, seasonal snowpacks, the snowpack meltwater's ionic pulse, and long-term snowpack-related records. The model environmental variables include those related to atmospheric mercury, insolation, wind, atmospheric stability, snowpack physical characteristics, atmospheric pressure, and solid precipitation. Bivariate and multiple linear regressions were performed twice for each mercury observation type: once with all observations, and once excluding observations from locations where the snowpack's burden of oxidizing and stabilizing halogens is known or presumed to affect snowpack mercury. Since no observations from long-term snowpack-related records were considered affected by halogens, this group of observations was included with the sets of uninfluenced observations and was not discussed with the complete, original sets of observations. When all observations are included, only 37% of their variability can be explained, on average, with significance confidence levels averaging 81%; a separate regression model predicts each mercury observation type. Without the influence of halogens, the regression models are able to explain an average of 79% of the observations' variability with significance confidence levels averaging 97%. The snowpack-related mercury observations are most strongly controlled by the dry and wet depositions of oxidized mercury, and by precipitation. Mercury deposited through wet processes is more strongly retained by snowpacks than mercury deposited through dry processes. Revolatilization of mercury deposited through wet processes may be inhibited through burial by fresh snowfalls and/or by its more central location, compared to that of mercury deposited through dry deposition, within snowpack snow grains. The two depositions of oxidized mercury together explain 84% of the variability in observed concentrations of mercury in surface snow, 52% of the variability of observed concentrations of mercury in seasonal snowpacks and their meltwater's ionic pulse, and only 20% of the variability of observed concentrations of mercury in long-term snowpack-related records; other environmental controls seemingly gain in relevance as time passes. The concentration of mercury in long-term records is apparently primarily affected by latitude; both the primary sources of anthropogenic mercury and the strong upper-level zonal winds are located in the midlatitudes.

Reduction of dioxin emissions from thermal waste treatment plants: a brief survey

Since 1977 dioxins were detected in fly ashes from waste incineration plants; this class of compounds is of major importance concerning the acceptance of this technology. Extended research and development revealed in short time the main formation mechanism of dioxins, the importance of good combustion control, the influence of halogens and sulphur, and paved the way for strategies for minimisation of formation, and efficient abatement. The main steps in this development as well as the current situation are described.

Halogen diffusion in magmatic systems: Our current state of knowledge

Diffusion of halogens has the potential to influence petrogenetic processes in magma chambers and conduit degassing processes. This contribution reviews our current state of knowledge concerning halogen diffusion and the influence of halogens on the diffusion of major elements in silicate melts. The addition of halogens to silicate melts at common, natural concentration levels will have little effect on the diffusion of major elements. However, the differences between the diffusivity of water, the diffusivities of halogens, and the diffusivity of sulfur are significant enough that during melt inclusion entrapment, or during rapid bubble or crystal growth, diffusive fractionation between water and the halogens, and between halogens and sulfur, are expected to occur and can influence the compositions of melt inclusions, crystals and volcanic gases.

Mechanism of Oxidation of 2,6‐Di‐tert‐butyl‐phenol with Molecular Oxygen, in Presence of Some New Bis(di‐halogeno α‐Methyl Salen) Copper(II) Complexes

A new series of the Cu(II) Schiff bases complexes were prepared and characterised. The studies followed the influence of halogens grafted on the aromatic rings of ligands on properties and reactivity of copper(II) complexes. The complexes was characterised by elemental analysis, FT‐IR, UV‐Vis and EPR spectroscopy and cyclic voltametry. The catalytic activity these complexes were tested by the oxygenation reaction of 2,6‐di‐tert butyl phenol with molecular oxygen. The reaction mechanism of oxidation involves reversible formation of [LCu‐O2] adducts.

The Influence of Halogens on the Electronic System of Biologically Important Ligands: Spectroscopic Study of Halogenobenzoic Acids, Halogenobenzoates and 5‐Halogenouracils

AbstractFor Abstract see ChemInform Abstract in Full Text.

Model study of multiphase DMS oxidation with a focus on halogens

Abstract. We studied the oxidation of dimethylsulfide (DMS) in the marine boundary layer (MBL) with a one-dimensional numerical model and focused on the influence of halogens. Our model runs show that there is still significant uncertainty about the end products of the DMS addition pathway, which is especially caused by uncertainty in the product yield of the reaction of the intermediate product methyl sulfinic acid (MSIA) with OH. BrO strongly increases the importance of the addition branch in the oxidation of DMS even when present at mixing ratios smaller than 0.5pmol mol-1. The inclusion of halogen chemistry leads to higher DMS oxidation rates and smaller DMS to SO2 conversion efficiencies. The DMS to SO2 conversion efficiency is also drastically reduced under cloudy conditions. In cloud-free model runs between 5 and 15% of the oxidized DMS reacts further to particulate sulfur, in cloudy runs this fraction is almost 100%. Sulfate production by HOClaq and HOBraq is important in cloud droplets even for small Br- deficits and related small gas phase halogen concentrations. In general, more particulate sulfur is formed when halogen chemistry is included. A possible enrichment of HCO3- in fresh sea salt aerosol would increase pH values enough to make the reaction of S(IV)* (=SO2,aq+HSO3-+SO32-) with O3 dominant for sulfate production. It leads to a shift from methyl sulfonic acid (MSA) to non-sea salt sulfate (nss-SO42-) production but increases the total nss-SO42- only somewhat because almost all available sulfur is already oxidized to particulate sulfur in the base scenario. We discuss how realistic this is for the MBL. We found the reaction MSAaq+OH to contribute about 10% to the production of nss-SO42- in clouds. It is unimportant for cloud-free model runs. Overall we find that the presence of halogens leads to processes that decrease the albedo of stratiform clouds in the MBL.

The influence of halogens and calcogens on four carbons normal chains as simple models for the perfluorooctanoate and related ions

Quantum mechanical calculations at HF/6-31+G level of theory were done to investigate the influence of the substitution of hydrogen by halogen atoms in amphiphilic molecules constituted by four-carbon normal chain ions as well as to investigate the effects of replacing the oxygen atoms at the polar head of the ions by sulfur and selenium atoms. In particular this work considers the following nine four-carbon chain ions: C 3X 7CO 2 −, C 3X 7CS 2 − (with X=H, F, Cl, Br) and C 3H 7CSe 2 −. While for the hydrogenate compounds the chain is almost linear and flexible others substitution lead a helicity of the carbonic chain and the ions becomes more and more stiff on going from fluorine to bromine. The calculated energy barrier for internal rotations of the polar head group and the internal rotation of the carbonic chain (about the central C–C bond) confirm these results. The influence of the length of the carbon chain was investigated at the same level of theory by calculating the optimized structure for the following six eight-carbon chains ions: C 7X 15CO 2 −, C 7Y 15CS 2 − (with X=H, F, Cl and Y=H, F) and C 7H 15CSe 2 −. The results show that the compounds with four- and eight-carbon chain are very similar having only small differences in the geometry and charge distribution at the polar head group of the ions.

The influence of selected metals and halogens on the electronic system of benzoic acid.

The influence of halogens and metals on the electronic system of the aromatic ring in lithium, sodium and potassium complexes with p-halogenobenzoic acids has been investigated by means of (13)C and (1)H NMR, IR and Raman spectroscopy and semi-empirical calculations. It has been shown that ionic potentials and electronegativities of halogens and metals are the main factors responsible for perturbations of the electronic charge distribution in the ring.

Determination of the influence of halogens on the strength properties of metals

Determination of the influence of halogens on the strength properties of metals

NMR-spektroskopische Untersuchungen an Chalkogenyerbindungen, III 77Se- und 18C-NMR-Daten von Verbindungen mit C=S- und C=Se-Doppelbindung / NMR Spectroscopic Studies on Chalcogen Compounds, III 77Se and 13C NMR Data of Compounds Containing C=S and C=Se Double Bonds

Abstract 77Se and 13C chemical shifts of compounds of type E=C=E′(E,E′=O, S, Se), Se = CF2, Se=C(NH2)2, Se = C(t-Bu)2 and 1,1,3,3-tetramethyl-2-indanselon are reported. The shielding of both nuclei in the C=Se entity depends strongly on the lowest electron excitation energy. 77Se-13C spin-spin coupling constants for the C=Se double bond are presented for the first time. The values show a strong dependence on the s-character of the carbon atom. This indicates an important Fermi contact contribution. Furthermore the influence of halogens, CF3S and CF3SS groups on the 13C chemical shift in thiocarbonyl compounds of the type S=C(Y)SCF3 (Y=F, Cl, Br) and S=C(SSCF 3)2 is described.

Influence of Halogens on the DC Conductivity and Magnetoresistance of (SN)x

AbstractExposure of (SN)x to the vapor of Br2, I2, and ICI leads to the componds (SNBr0.4)x, (SNI0.02)x, and [SN(ICI)0.1]x, respectively. The second and the third one of these compounds have not been reported before. In the temperature range 4.2 to 300 K the de conductivity is increased in (SN Br0.4)x and (SNI0.02)x and lowered in [SN(ICI)0.1]x compared to the pristine (SN)x. The anisotropy of the de conductivity in (SN Br0.4)x is about 10 times higher than in (SN)x. Measurements of the transverse magnetoresistance at 4.2 K in all three materials indicate increased disorder due to doping with the halogens.

Reactions of ?-benzyl-?-cyclopentadienyliron dicarbonyl

1. σ-Benzyl-π-cyclopentadienyliron dicarbenyl is acylated in the benzene ring under the conditions of the Friedel-Crafts reaction. 2. The iron-carbon σ-bond in σ-benzyl-π-cyclopentadienyliron dicarbonyl was cleaved under the influence of halogens, mercuric bromide, and trifluoroacetic acid.