Chlorine Anions Research Articles

Role of ionic chlorine in the thermal degradation of metal chloride-doped graphene sheets

The degradation mechanism of graphene sheets doped with metal chloride was investigated as a function of the annealing process. The sheet resistance of doped graphene increased from 500–700 Ω sq−1 to 10 kΩ sq−1 and the transmittance at 550 nm decreased from 95% to 87–91% after annealing at 400 °C. Furthermore, the work function of doped graphene decreased from 4.7–5.1 eV to 4.2–4.5 eV after annealing. The G and 2D band peaks in the Raman spectra were shifted to lower wavenumbers by annealing at 400 °C, regardless of the kind of dopant, and reached nearly the same level as that of the pristine graphene. X-ray photoemission spectroscopy showed that the chlorine anions and chlorine atoms disappeared after thermal annealing. The scanning electron microscopy images revealed the capability of annealing to gather the unstable metal cations, thereby inducing the aggregation of metal particles. The degree of doping of the graphene sheets was strongly related to not only metal cations but also chlorine anions. Therefore, aggregation of metal particles and adsorption of chlorine ions degraded the properties of graphene as a function of annealing temperature.

NBO Analysis the Chlorine Anion Recognition Mechanism of the Urea-Based Involving Iodine and Fluorine Derivation Functional Molecular Material

The recognition mechanism of the urea-based non-involving fluorine (A) and involving fluorine (B) derivation receptors for the chlorine anion (Cl-) was discussed by using the density function B3LYP method. The results showed that recognition mechanism was performed by using four coordination weak bonds, which include two N-H…Cl hydrogen bonds and two C-I…Cl halogen bonds. The calculated interaction energies (ΔECP) with basis set super-position error (BSSE) correction of the two systems are -121.78 and -179.71 kJ•mol-1, respectively. So, the urea-based involving fluorine derivation receptor (B) presents the better recognition capable for the Cl-. Natural bond orbital theory (NBO) analysis has been used to investigate the electronic behavior and property of the N-H…Cl hydrogen bonds and two blue-shift C-I…Cl halogen bonds in the A…Cl- and B…Cl- recognition systems, respectively.

Ion doping of graphene for high-efficiency heterojunction solar cells

We demonstrated the p-type chemical doping by chlorine and nitrate anions to enhance the Schottky junction in the solar cell. Nitrate ions were found to be more effective for reducing the sheet resistance and enlarging the work function of graphene for effective charge separation and transport, and the efficiency was increased to 9.2% by a factor of 1.68 under AM 1.5 illumination.

The Geometry Structures and IR Properties of the Urea-Based Derivation Functional Molecular Materials Used for the Chlorine Anion Recognition

The geometry structures and IR properties of the non-involving fluorine (A) and involving fluorine (B) urea-based derivation receptors used recognition for chlorine anion (Cl-) was investigated by using the density function Becke, three-parameter, Lee-Yang-Parr (B3LYP) method. The involving fluorine urea-based derivation receptor (B) presents a better recognition capable for the Cl-. In the A…Cl- recognition system, the stretch vibrational frequency of the N-H bond presents an obvious red-shift, and the red-shift value higher than 12.4 cm-1, moreover, the IR intensity increased from 8.26 km•mol-1 of the monomer to 312.12km•mol-1 of the recognition system. However, as for the C-I bonds of the halogen bond donors of the receptor molecules A and B, their stretch vibrational frequencies present the different potential shift.

Crystal structures of 2,2′:6′,2″-terpyridine uranyl chlorides molecular assemblies and their luminescence signatures

A series of three compounds bearing uranyl cations and 2,2′:6′,2″-terpyridine (terpy) has been hydrothermally synthesized from uranium tetrachloride aqueous solution. An oxidation process into the hexavalent state has been observed for uranium in these synthesis conditions, together with the crystallization of different phases, which have been characterized by single-crystal X-ray diffraction analysis. The tetrachloridodioxidouranate terpyridinium salts UO2Cl4·H2terpy·H2O (1) and UO2Cl4·(H2terpy)2·2Cl (2) consist of the molecular assemblies of tetrachloro-uranyl anions ([UO2Cl4]2−, square plane bipyramidal environment), isolated to each other via the doubly protonated H2terpy molecules. The latter chelate either water (1) or chlorine anions (2). The addition of organic base such as pyridine favored the crystallization of the complex, UO2Cl2(terpy) (3), with the neutral terpy moiety coordinating one uranyl center via the nitrogen atoms of the pyridyl rings. It resulted in one uranyl center bonded to three nitrogen and two terminal chlorine anions, located in a distorted equatorial plane and two terminal perpendicular uranyl oxygens in apical position of a pentagonal bipyramid ([UO2Cl2N3]). Different π–π interactions between the pyridyl rings of neighboring terpy molecules also occur for these complexes. Fluorescence spectroscopy of these different complexes has been measured at room temperature and 77K showing the various local environments of the emitting centers.

A regional examination of episodic acidification response to reduced acidic deposition and the influence of plantation forests in Irish headwater streams

Episodic surface water acidification is common in many regions worldwide; the driving processes are dependent on a variety of physicochemical and climatic characteristics, and acid deposition pressures, which have changed significantly over the last two decades. This study provided a unique opportunity to re-examine the drivers of acidity in an environment of low anthropogenic input. In three geologically distinct acid-sensitive regions of Ireland during 2009–2010, 34 headwater streams were evaluated in peat-dominated catchments draining moorlands without forest, 20–50% (low) forest cover and >50% (high) forest cover. Results indicated episodic acidity/alkalinity loss in headwater streams, despite significant reductions in acid deposition. Both the differences in pH between base and storm-flow (∆pH) and the number of pH events≤5.5 were higher in forested streams. Dissolved organic carbon and inorganic aluminium concentrations were also higher in forested catchments. The primary driver of acidity was strong organic anions, which generally increased with increasing forest cover. Base-cation dilution was also prominent in west and southern regions, while surprisingly chlorine anion acidity from sea-salts had little or no influence on stream acidity. The contributions of excess non-marine sulphate (xSO4) and nitrate (NO3) to storm-water were low, with no observed increases in xSO4 with increasing forest cover, although contributions of NO3 were higher in forested catchments in the east. The results suggest that episodic acidification in Ireland is primarily driven by organic acids. However in peat dominant catchments, plantation forest, climate change and/or reductions in xSO4 appear to also be having an effect on stream pH from increased DOC, with some forested streams previously unaffected by deposition now showing low pH (<5.5) during storm-flow. As quantified from this study, observed changes in stream acidification in Ireland may provide a better understanding of future chemical responses to declining acid deposition and climate change elsewhere.

Synthesis, crystal structure, DNA interaction and anticancer activity of tridentate copper(II) complexes

Three new tridentate copper(II) complexes [Cu(dthp)Cl2] (1) (dthp=2,6-di(thiazol-2-yl)pyridine), [Cu(dmtp)Cl2] (2) (dmtp=2,6-di(5-methyl-4H-1,2,4-triazol-3-yl)pyridine) and [Cu(dtp)Cl2] (3) (dtp=2,6-di(4H-1,2,4-triazol-3-yl)pyridine) have been synthesized and characterized. Crystal structure of complex 1 shows that the complex existed as distorted square pyramid with five co-ordination sites occupied by the tridentate ligand and the two chlorine anions. Ethidium bromide displacement assay, viscosity measurements, circular dichroism studies and cyclic voltammetric experiments suggested that these complexes bound to DNA via an intercalative mode. Three Cu(II) complexes were found to efficiently cleave DNA in the presence of sodium ascorbate, and singlet oxygen (1O2) and hydrogen peroxide were proved to contribute to the DNA cleavage process. They exhibited anticancer activity against HeLa, Hep-G2 and BEL-7402 cell lines. Nuclear chromatin cleavage has also been observed with AO/EB staining assay and the alkaline single-cell gel electrophoresis (comet assay). The results demonstrated that three Cu(II) complexes cause DNA damage that can induce the apoptosis of BEL-7402 cells.

Crystal structure and magnetic properties of two new zoledronate complexes: A Mn dimer [Mn(II)(H3Zol)2·(H2O)2] and a Fe15 molecular cluster [Fe(III)15(HZol)10(H2Zol)2 (H2O)12(Cl4:(H2O)2)·Cl7·(H2O)65] (where H4Zol: C5H10N2O7P2 is zoledronic acid)

The synthesis, X-ray structure and magnetic properties of two new zoledronato complexes are presented: Mn(II)(H3Zol)2(H2O)2, (I) and Fe(III)15(HZol)10(H2Zol)2 (H2O)24 (2/3Cl:1/3H2O)6·7Cl·65(H2O) (II), where H4Zol=zoledronic acid=C5H10N2O7P2. Complex (I) is a dimer, built up around an inversion centre where the cation is located, surrounded by two chelating zoledronate anions and two water molecules. The structure is isomorphous to the Co, Ni and Zn isologues. A quite different structure is the Fe(III) complex which consists of a centrosymmetric cluster with 15 Fe(III) cations (one of them at the inversion centre), 12 zoledronate anions, in different protonation states and 26 coordinated water molecules, 24 of which show full occupancy and the remaining 2 share 6 coordination sites with 4 chlorine anions. There are in addition 7 chlorine counterions and a not well determined number of hydration water molecules, their number being adjusted as to match the chemical and TGA analysis. The general shape of the molecule is that of a 6 arm propeller with a Fe(III) cation at its center and two FeO6 coordination polyhedra sitting above and below, defining some sort of “paddle wheel axis”, perpendicular to the wheel plane. Around this axis there is an almost perfect circular structure formed by other six FeO6 octahedra, to which the “paddles”, defined by the remaining six FeO6 groups attach. The ensemble presents some unusual (Fe···OPO)n loops (n=2,3,4), some of them unreported, and displays a striking non-crystallographic −3 symmetry. The protonation state of the zoledronato ligands were inferred from the counterions effectively found and charge balance considerations. Both compounds present a paramagnetic behaviour at R.T, and obey a Curie Weiss law down to rather low temperatures (15K for (I), 100(K) for (II)) with a tendency to different types of interactions viz., ferromagnetic for (I) and antiferromagnetic for (II). The geometry of the F15 cluster is analyzed.

Synthesis of Efficient Nanosized Rutile TiO2 and Its Main Factors Determining Its Photodegradation Activity: Roles of Residual Chloride and Adsorbed Oxygen

Nanosized TiO2 containing different contents of rutile phase was controllably synthesized by a hydrochloric acid-modified hydrothermal process. It is demonstrated that the formation of rutile phase in TiO2 mainly depends on the role of chlorine anions in the synthesis, and a certain amount of residual chloride would exist on the surfaces of the resulting nanocrystalline rutile TiO2. Interestingly, the as-prepared rutile shows high activity for photodegradation of rhodamine B dye compared with the as-prepared anatase, even superior to the P25 TiO2. It is mainly attributed to the residual chloride that could promote the dye adsorbed on the surfaces of TiO2, consequently accelerating the photosensitization oxidation reactions of the dye molecules. In the photodegradation of liquid-phase phenol and gas-phase aldehyde, the as-prepared rutile TiO2 samples display low activity, which is attributed to the photogenerated electrons weakly captured by the adsorbed oxygen, since the residual chloride could effectively capture photoinduced holes based on the atmosphere-controlled surface photovoltage spectroscopy results. Further, the photoactivity of resulting rutile for degrading phenol and aldehyde is greatly enhanced by modifying a proper amount of phosphoric acids to increase the adsorption of O2, even higher than that of the P25 TiO2. This work would explore feasible routes to synthesize efficient nanosized rutile TiO2-based photocatalysts for degrading colored and colorless organic pollutants by investigating the rate-determining factors in the photodegradation processes.

Nucleation of water vapors at temperatures above the boiling point in the presence of ion admixtures

The dependences of the Gibbs energy, entropy, and work of formation on the sizes of the centers of nucleation of a condensed phase with the size of up to 533 molecules formed on singly charged sodium cations and chlorine anions in water vapor at the temperature of 400 K have been calculated on the molecular level by the Monte Carlo method. It has been shown that, when the detailed interaction model is used, the effect of pulling the ion from microdroplets is kept at relatively high temperatures, accelerating the loss of the thermodynamic stability of the center of nucleation and the formation of the typical nucleation barrier, the same as in homogeneous microdroplets. When ion admixtures are present, the free energy barrier to the growth of centers of nucleation in strongly supersaturated vapors is considerably lowered. The nucleation velocity and minimum relative contents of the ion admixtures, able to accelerate nucleation, have been estimated in the region of strong supersaturation.

Anodic chlorine/nitrogen co-doping of reduced graphene oxide films at room temperature

Room temperature simultaneous doping of reduced graphene oxide films with oxygen, nitrogen and chlorine was performed through anodic polarization in a neutral nitrogen-deaerated KCl electrolyte. The thermodynamic electrochemical windows of water, dissolved nitrogen and chlorine anions were analyzed on the basis of the Pourbaix diagram. Anode polarization demonstrated that the nitrogen, water and chlorine anions can be oxidized at an applied potential of 1.7V vs. NHE. The oxidative products, i.e. oxygen, nitrate anion and hypochlorous acid, can react with the reduced graphene oxide surface. X-ray photoelectron spectroscopy proved the chlorine–nitrogen co-doping of the treated film, along with an increase of oxygen groups. Surface structure evolution was also confirmed by Raman and Fourier-transform infrared spectroscopies. The anodic doping can be hindered by covering the reduced graphene oxide surface with sulfate anions or forming stable carbon–nitrogen bonds. Incorporation of oxygen, nitrogen and chlorine also helps to enhance the supercapacitance of the doped film.

Stable associates of polyether oligomers with chlorine anion as revealed by the data of electrospray mass spectrometry and molecular dynamics

Stable complexes of oligomers of polyether (oxyethylated glycerol derivatives) with a chlorine anion have first been registered in negative-ion electrospray ionization mass spectra. The results of molecular dynamics simulation demonstrate that the stabilization of such complexes in the gas phase can be due to the formation of a quasicyclic structure of the polymer chain around the chlorine anion and its coordination by CH2- and OH- groups of the oligomer. This structure is inverted towards the known quasicyclic structure of polyethers, in which metal cations are coordinated by oxygen atoms of ether groups.

4-Chloro-selanyl-3,5-diethyl-1H-pyrazol-2-ium chloride.

In the cation of the title compound, C7H12ClN2Se+·Cl−, the ethyl­ene groups and the Se–Cl fragment adopt a cis configuration with a C—Se—Cl angle of 96.09 (6)°. In the crystal, inter­molecular N—H⋯Cl hydrogen bonds link two cations and two chlorine anions into centrosymmetric clusters. π–π inter­actions between the pyrazole rings [centroid–centroid distance of 3.530 (2) Å] link these clusters into columns along [001] with short inter­molecular Se⋯Cl− contacts of 2.995 (1) Å.

Preparation, characterization and single-cell performance of a new class of Pd-carbon nitride electrocatalysts for oxygen reduction reaction in PEMFCs

This report describes the preparation of two Pd-based carbon nitride electrocatalysts for the oxygen reduction reaction (ORR) for application in polymer electrolyte membrane fuel cells (PEMFCs). The electrocatalysts consist of multi-metallic active sites supported on a graphite-like carbon nitride (CN) matrix with a N content exceeding 13wt%. The electrochemical performance is investigated by cyclic voltammetry with the thin-film rotating disk electrode method (CV-TF-RDE) and evaluated in a single membrane electrode assembly (MEA) PEMFC. The correlation of the structural information to functional properties allows to propose a reaction mechanism and to identify the most desirable features to achieve in a CN electrocatalyst in order to obtain desired electrochemical performance in catalysis of ORR. It is established also that the CN support improves the tolerance towards the catalyst corrosion under oxidizing conditions and thus improves the catalyst durability. The stoichiometry and the morphology of Pd-based CN electrocatalysts play a crucial role in the modulation of the tolerance towards common ORR poisons such as chlorine anions and methanol. Finally, the performance of the Pd-based CN electrocatalysts in a single MEA PEMFC proved promising.

Oxidative coupling of methane using non-stoichiometric lead hydroxyapatite catalyst mixtures

Lead hydroxyapatite (PbxCa10−x(PO4)6(OH)2, 0<x⩽10) is one of the most active catalysts for oxidative coupling of methane (OCM) to produce ethane and ethylene from natural gas (methane). In this study, we investigated how the OCM activity of a precipitated lead hydroxyapatite is associated with its mixture and non-stoichiometric properties. Lead hydroxyapatite was prepared through aqueous precipitation in the presence of chlorine anions and calcination under helium background at 1073K, which resulted in a mixture of non-stoichiometric lead hydroxyapatites, each having a different cationic composition (PbxCa10−x). The mixture could be diversified by extracting the chlorines thermally from the chloro-hydroxyapatites of various chlorine contents. The formation of an apatite structure was confirmed through Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), X-ray fluorescence (XRF) and inductively coupled plasma (ICP) analyses. The non-stoichiometric characters of the prepared hydroxyapatites were analyzed through Raman/FT-Raman spectroscopy. The C2 selectivities of the prepared catalysts were evaluated at 1048K with a fixed CH4 conversion of 35%. Among the tested catalysts, lead hydroxyapatite, which was obtained by removing chlorines from Pb2Ca8(PO4)6(OH)0.5Cl1.5, showed a C2 selectivity of 62%, and achieved a C2 yield of 22% at 1048K. The OCM activity of the catalyst was mainly associated with its surface basicity, which was investigated using CO2-temperature-programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS) analyses.

Positive and Negative Photoion Spectroscopy Study of Monochlorothiophenes

Photolysis dynamics of monochlorothiophenes (2- and 3-chlorothiophenes) is investigated using positive and negative photoion mass spectrometry combined with the synchrotron vacuum ultraviolet radiation. A dozen of the daughter cations are observed in the time-of-flight mass spectra, and their appearance energies are determined by the photoion efficiency spectroscopy measurements. At the energetic threshold, the concerted process rather than a stepwise reaction for C(4)H(3)SCl(+) → C(2)HSCl(+) + C(2)H(2) and the ring-open isomers of the dehydrogenated thiophene cations (C(4)H(3)S(+) and C(4)H(2)S(+)) formed in C(4)H(3)SCl(+) → C(4)H(3)S(+) + Cl and C(4)H(2)S(+) + HCl are proposed on the basis of the B3LYP/6-311+G(3df,3pd) calculations. The chlorine anion (Cl(-)) is observed as the product of the photoion-pair dissociations in the energy range of 10.70-22.00 eV. A set of valence-to-Rydberg state transitions 12a' → np (n = 6, 7, 8, 9, 10, etc.) and several series of vibrational excitations are tentatively assigned in the Cl(-) spectrum of 2-chlorothiophene in the lower energy range of 10.90-12.00 eV.

Hydrothermal synthesis and crystal structure of a novel nickel(II) complex: [Ni(H2Bibzim)3Cl2 · 2H2O] (H2Bibzim = 2,2-Bibenzimidazole)

A novel organic-inorganic hybrid compound based on weak intermolecular interactions formulated as Ni(H2Bibzim)3Cl2 · 2H2O (H2Bibzim = 2,2-bibenzimidazole, formula, C14H10N4) has been synthesized under hydrothermal conditions and characterized by elemental analysis, single-crystal X-ray diffraction analyses, and IR spectra. It crystallizes in the orthorhombic system, space group Pbcn, Z = 2, a = 20.8530(19), b = 15.7838(14), c = 12.3159(11) A, V = 4053.7(6) A3, Mr = 1736.84, ρc = 1.423g/cm3, λ = 0.71073 A, μ(MoKα) = 0.664 mm−1, F(000) = 1792, R = 0.0283 and wR = 0.0707 for 3746 observed reflections with I > 2σ(I). The complex is composed of mononuclear cations [Ni(H2Bibzim)3]2+, chlorine anions, and lattice water molecules, which are linked into a two-dimensional supramolecular architectures via hydrogen bonds and π-π-stacking interactions.

Geminate Charge Recombination in Liquid Alkane with Concentrated CCl4: Effects of CCl4 Radical Anion and Narrowing of Initial Distribution of Cl–

Dynamics of radical cations and electrons in an admixture of a linear saturated hydrocarbon (n-dodecane) and halocarbon (carbon tetrachloride, CCl(4)) were investigated by picosecond electron beam pulse radiolysis. The decay of thermalized electrons (e(th)(-)) observed in infrared transient photoabsorption were simply accelerated by the addition of CCl(4), giving a high rate constant of 2.3 × 10(11) mol(-1) dm(3) s(-1). The decrease of the initial yield of e(th)(-) was quantified by C(37) (50 mmol), which is linked to the reaction of epithermal electrons (e(-)) with CCl(4). In contrast, the n-dodecane radical cation (RH(2)(•+)) monitored in the near-infrared indicated a convex-type dependence of the decay rate on CCl(4) concentration, although the initial yield of RH(2)(•+) remained almost constant up to a much higher CCl(4) concentration. The decay of RH(2)(•+) was analyzed by Monte Carlo simulations of geminate ion recombination with e(th)(-), chlorine anion (Cl(-)) formed via dissociative electron attachment, and CCl(4) radical anion. The results showed a good agreement with the experiments by considering two assumptions: (1) CCl(4) radical anion formed via e(th)(-) attachment and (2) narrowing of the initial distribution of Cl(-). The decrease in the initial yield of RH(2)(•+) at high CCl(4) concentration was well explained by immediate decomposition of CCl(4)(•+) to CCl(3)(+) and hole transfer from CCl(4)(•+) to adjacent RH(2) without diffusive motion of the reactants. Time-dependent density functional theory supported the spectroscopic assignment of intermediate species in the n-dodecane/CCl(4) system. The present results would be of help in understanding the electron capture reaction in multicomponent systems such as a chemically amplified resist in lithography.

Effect of chlorine ions on the stability of nucleation cores in condensing water vapors

The Gibbs energy and the equilibrium work of nucleation of condensed-phase nuclei in water vapors in the presence of chlorine anions are calculated at the molecular level using the Monte Carlo method at a temperature of 273 K for sizes of up to 200 molecules. It is found that the growth of a nucleus leads to the displacement of a chloride ion onto its surface, which is accompanied by a loss of the thermodynamic stability of the microdroplet. It is found that the size dependence of the work of nucleation exhibits a minimum and a maximum with an inflection point that separates the region of stable and unstable equilibrium sizes.

Mesoporous zirconosilicate doughnuts with high performance in liquid oxidative dehydrogenation of hydroquinone to quinone

Unusual partially crystalline ordered mesoporous zirconosilicate doughnuts with Si/Zr ratio as low as 1.5 were synthesized from the aqueous polymerisation of a single source molecular precursor Zr[OSi(Ot-BuO)3]4 without the use of any templating agent. A radial homogenous mesoporosity (4nm) was observed inside these very regular sub-micrometric (600nm) doughnuts. These structures were partially crystallized in hydrothermal conditions (100°C) into an analogous zircon (ZrSiO4) framework. The formation mechanism has been investigated. It is evidenced that chlorine anions Cl− concentration and pH value are essential to achieve the process, even if their role is still a matter of investigations. The obtained materials demonstrated even higher catalytic activity, selectivity and stability in the liquid oxidative dehydrogenation of hydroquinone to 1,4-benzoquinone compared to TS-1 zeolite catalysts and amorphous highly ordered mesoporous zirconosilicate materials.