Cl2 Molecules Research Articles

Polychlorinated Biphenyls Interactions with Water—Characterization Based on the Analysis of Non-Covalent Interactions and Energy Partitioning

Although polychlorinated biphenyls (PCBs) have been long banned from use, both they and dioxins are still considered persistent organic pollutants. The reason is twofold: their relative inertness (especially to oxidation) and their ability to accumulate in fat tissue. The current study sheds light on the interactions of PCBs with water, chlorine, and chlorine dioxide. Necessary insight is gained from Atoms in Molecules (AIM) and Non-Covalent Interactions (NCI) index and analyses for the 1:1 complexes of PCBs with water and chlorine (Cl2) molecules. Further, Symmetry-Adapted Perturbation Theory (SAPT) calculations reveal the strength and nature of the intermolecular interactions, and the presence of halogen bonding is demonstrated in AIM, NCI, and SAPT studies. The stability of water, chlorine, and chlorine dioxide (ClO2) complexes with PCBs is discussed using the supramolecular MP2 approach. Finally, analysis of microsolvation shells of PCBs showed the origins of the hydrophobicity and environmental persistence of these chemicals. Our results are applicable to the sustainability of water treatment strategies providing a description of forces and interactions at the molecular level.

Adsorption and dissociation of Cl2 on CuO(111) surface with first-principles study

The first principle calculation based on density functional theory (DFT) was used to discuss the adsorption and dissociation behaviors of Cl2 on the perfect and oxygen-deficient surfaces of CuO(111) in this paper. The adsorption behavior and reaction mechanism of Cl2 directly adsorbed on two CuO(111) surfaces were analyzed by calculating the adsorption structure, energy of adsorption, charge density difference, the electron localization function and density of states (DOS) of the system. The calculations suggest that the most advantageous site for Cl2 adsorption on the perfect CuO(111) surface is the bridge site between two Cusub atoms. However, on the oxygen-deficient CuO(111) surface, two Cl atoms dissociated from the Cl2 molecule and bound to the Cu site after optimization. The calculations indicate that the existence of oxygen vacancy is highly chemically reactive when it comes to the dissociation of Cl2, which can increase the activity of CuO significantly. Our calculations of the adsorption and dissociation of Cl2 on the CuO(111) surface can offer some microscopic information for the side products of CuO and Cl2 produced by the thermolysis of copper oxychloride and the effect of side reaction on yield.

First principles study of NH3, H2S, Cl2, and C2H2 gases adsorption on defective GaSe monolayer

Toxic gases emission poses serious environmental concerns and health risks. The Van der Waals type of layered materials is an emergent class of materials with extraordinary physicochemical properties which are highly attractive for gas sensors. This study report on the potential applications of the interaction between toxic gases of NH3, H2S, Cl2, and C2H2 and the defective GaSe monolayer with Se vacancy, O-doped, and N-doped based on density functional theory. The defective GaSe monolayer enhances the adsorption energy and charge transfer value after four toxic molecules are adsorbed on it, particularly, the Cl2 molecule is adsorbed on the Se-vacancy site of the GaSe monolayer. The distance between four toxic molecules and the defective GaSe monolayer is significantly reduced after adsorption.

Experimental and theoretical approach for novel imidazolium ionic liquids as Smart Corrosion inhibitors for mild steel in 1.0 M hydrochloric acid

3-(4-hydroxybutyl)-1-phenethyl-1H-imidazol-3-ium chloride ([HB-Imid] Cl), and 3-(2-chlorobenzyl)-1-phenethyl-1H-imidazol-3-ium chloride ([CB-Imid] Cl) were investigated as corrosion inhibitors for mild steel in 1.0 M hydrochloric acid solution. Electrochemical techniques (PDP and EIS) were performed as experimental studies while DFT at B3LYP 6-311G (df,pd), and molecular dynamic simulation were used as theoretical approach. PDP experiments revealed that the studied ionic liquids (ILs) behaved as mixture type inhibitors. EIS results indicated that these compounds showed good inhibition performance with inhibition efficiency around 95% at the optimum concentration of 1.0 × 10−3 M. According to Langmuir isotherm model and the thermodynamic parameters, these ILs were adsorbed onto the mild steel surface through physical and chemical bonds. SEM and EDX examinations proved the formation of a protective layer of adsorbed inhibitors at the steel surface. The DFT/B3LYP/6-311G(df,pd) computations in both the gas and water environments disclosed that [HB-Imid] Cl molecule was softer and had a lower energy gap, electrodonating power, and polarizability indexes.

Atomistic kinetic Monte Carlo simulation on atomic layer deposition of TiN thin film

The atomic layer deposition (ALD) process of TiN thin films is widely used in microelectronics, but the detailed growth mechanism is still elusive at the atomistic level. In the present computational study, we carry out kinetic Monte Carlo (kMC) simulations on the ALD process using TiCl4 and NH3 precursors. Based on the on-lattice model, we sort out key reactions relevant for the ALD process such as adsorption/desorption of precursors, generation of surface Cl atoms, and evolution of free HCl and Cl2 molecules. The reaction energies considering local environments are calculated at the level of density functional theory (DFT) while the activation barriers are linearly fitted to sampled cases among distinct reaction families. The resulting kMC model produces the temperature-dependent growth rates and the amounts of Cl residues in reasonable agreement with experiments. The detailed growth pathway is discussed based on the simulation results, which underscores the critical role of surface Cl atoms in the ALD process by generating HCl gas molecules. By revealing the atomistic mechanisms in the TiN-ALD process, the present work would help optimize material properties of TiN thin films.

Microwave assisted co-operative dynamics and structural variations in chlorobenzene-acetonitrile solutions

Molecular interactions between CBZ-ACN at 8.845 GHz of microwave frequency region confer structural behavior of molecules such that either monomers or multimers are present in the agreed binary mixtures. Effect of microwave frequency on molecular interactions and hydrogen bonding between C≡N (nitrile) molecule and Cl (chlorine) molecule of CBZ and ACN binary solutions has been studied using X-band microwave technique at 301ºK. Co-operative dynamics and hydrogen bonding between nitrile and chlorine group molecules has been thoroughly explicated thereby obtaining static dielectric constant, excess permittivity, Kirkwood correlation factor using Luzar model and Bruggeman factor.
 Bangladesh J. Sci. Ind. Res. 57(2), 85-90, 2022

Adsorption and Sensing Performances of Pristine and Au-Decorated Gallium Nitride Monolayer to Noxious Gas Molecules: A DFT Investigation.

In this study, the adsorption of noxious gas molecules (NO, Cl2, and O3) on GaN and Au-decorated GaN was systematically scrutinized, and the adsorption energy, bond length, charge, density of state (DOS), partial density of state (PDOS), electron deformation density (EDD), and orbitals were analyzed by the density functional theory (DFT) method. It is found that the interaction between NO and pristine GaN is physical adsorption, while GaN chemically reacts with Cl2 and O3. These observations suggest that pristine GaN may be a candidate for the detection of Cl2 and O3. The highly activated Au-decorated GaN can enhance the adsorption performance toward NO and convert the physical adsorption for NO into chemical adsorption, explaining the fact that precious metal doping is essential for regulating the electronic properties of the substrate material. This further confirms the well-established role of Au-decorated GaN in NO gas-sensing applications. In addition, the adsorption performance of Au-decorated GaN for Cl2 and O3 molecules is highly improved, which provides guidance to scavenge toxic gases such as Cl2 and O3 by the Au-decorated GaN material.

Critical Computational Evidence Regarding the Long-Standing Controversy over the Main Electrophilic Species in Hypochlorous Acid Solution.

Although hypochlorous acid (HOCl) solution has become a popular electrophilic reagent for industrial uses, the question of which molecule (HOCl or Cl2) undergoes electrophilic addition with olefins remains a controversial issue in some literature and textbooks, and this problem has been largely underexplored in theoretical studies. In this work, we computationally studied the electrophilic addition mechanism of olefins using three experimentally predicted effective electrophilic chlorinating agents, i.e., HOCl, Cl2, and Cl2O molecules. Our results demonstrate that Cl2 and Cl2O are the main electrophilic agents in HOCl solution, whereas the HOCl molecule cannot be the electrophile since the energy barrier when directly adding HOCl molecule to olefins is too high to overcome and the “anti-Markovnikov” regioselectivity for tri-substituted olefin is not consistent with experiments. Notably, the HOCl molecule prefers to form oxonium ion intermediate with a double bond, rather than the generally believed chlorium ion intermediate. This work could benefit mechanistic studies of critical biological and chemical processes with HOCl solution and may be used to update textbooks.

Fluorine and chlorine gas storage by confinement inside Boron Nitrogen Nanotubes

DFT calculations using the WB97XD and CAM-B3LYP functional and the basis set 6-31G(d,p) were performed to study the interaction between the X 2 (X=F or Cl) molecule and boron nitrogen nanotubes (BNNTs). Each molecule was confined within BNNTs with different dimensions in either parallel or perpendicular positions along the nanotube axis. The interaction between X 2 molecule and the BNNT nanotube differed according to the extension of the confinement space and the molecular orientation. Unlike Cl 2 , F 2 forms a very stable complex with the (4,4) and (5,5) BNNTs. The van der Waals interactions of the X 2 molecule with the BNNT leads to charge transfer and a change in the charge distribution in the X 2 molecule, producing a new detectable infrared signal of the X-X bond stretch that is nanotube’s diameter dependent.

Low Energy Electron Attachment by Some Chlorosilanes.

In this paper, the rate coefficients (k) and activation energies (Ea) for SiCl4, SiHCl3, and Si(CH3)2(CH2Cl)Cl molecules in the gas phase were measured using the pulsed Townsend technique. The experiment was performed in the temperature range of 298–378 K, and carbon dioxide was used as a buffer gas. The obtained k depended on temperature in accordance with the Arrhenius equation. From the fit to the experimental data points with function described by the Arrhenius equation, the activation energies (Ea) were determined. The obtained k values at 298 K are equal to (5.18 ± 0.22) × 10−10 cm3·s−1, (3.98 ± 1.8) × 10−9 cm3·s−1 and (8.46 ± 0.23) × 10−11 cm3·s−1 and Ea values were equal to 0.25 ± 0.01 eV, 0.20 ± 0.01 eV, and 0.27 ± 0.01 eV for SiHCl3, SiCl4, and Si(CH3)2(CH2Cl)Cl, respectively. The linear relation between rate coefficients and activation energies for chlorosilanes was demonstrated. The DFT/B3LYP level coupled with the 6-31G(d) basis sets method was used for calculations of the geometry change associated with negative ion formation for simple chlorosilanes. The relationship between these changes and the polarizability of the attaching center (αcentre) was found. Additionally, the calculated adiabatic electron affinities (AEA) are related to the αcentre.

Nanosystem’s density functional theory study of the chlorine adsorption on the Fe(100) surface

Abstract This contribution investigates chlorine (Cl) interaction with the Fe(100) surface, with a focus on governing adsorption energies and geometrical features at the nanoscale using the density functional theory (DFT) approach. The Cl/Fe(100) system can be considered as a building block to create nanosystems with specific and desired electronic, material, mechanical, or environmental properties. We report adsorption energies, surface relaxations. and buckling distances for Cl adsorbed as a function of Cl coverage. The computational DFT framework employs a vdW-DF functional with coverages varying from 0.25 to 1 ML. Adsorption at a bridge site with coverage of 0.5 ML appears to be the most preferred site, with an adsorption energy of −4.44 eV. For all coverages, Cl adsorption at the bridge and hollow sites incurs slightly higher adsorption energies than adsorption at the top (T) site. The potential energy surface (PES) for the dissociation of a Cl molecule over the Fe(100) surface was calculated. Dissociative adsorption of the Cl molecule on Fe(100) ensues via a modest activation barrier of only 0.58 eV in a noticeably exothermic reaction of 2.94 eV. In agreement with experimental observations, the work function decreases upon Cl addition in reference to the clean iron surface. The electronic interaction between Cl and the Fe(100) surface was examined by calculating the differential charge density distribution of the most stable structure (B-0.5 ML). The vdW-DF interactions increase the adsorption energies and reduce the equilibrium distances when compared with the corresponding results from plain DFT.

Simulation Verification of Barrierless HONO Formation from the Oxidation Reaction System of NO, Cl, and Water in the Atmosphere.

Nitrous acid (HONO) is a major source of hydroxyl (OH) radicals, and identifying its source is crucial to atmospheric chemistry. Here, a new formation route of HONO from the reaction of NO with Cl radicals with the aid of one or two water molecules [(Cl) (NO) (H2O)n (n = 1-2)] as well as on the droplet surface was found by Born-Oppenheimer molecular dynamic simulation and metadynamic simulation. The (Cl) (NO) (H2O)1 (monohydrate) system exhibited a free-energy barrier of approximately 0.95 kcal mol-1, whereas the (Cl) (NO) (H2O)2 (dihydrate) system was barrierless. For the dihydrate system and the reaction of NO with Cl radicals on the droplet surface, only one water molecule participated in the reaction and the other acted as the "solvent" molecule. The production rates of HONO suggested that the monohydrate system ([NO] = 8.56 × 1012 molecule cm-3, [Cl] = 8.00 × 106 molecule cm-3, [H2O] = 5.18 × 1017 molecule cm-3) could account for 40.3% of the unknown HONO production rate (Punknown) at site 1 and 53.8% of Punknown at site 2 in the East China Sea. This study identified the importance of the reaction system of NO, Cl, and water molecules in the formation of HONO in the marine boundary layer region.

Optical Absorption of Excimer Laser‐Induced Dichlorine Monoxide in Silica Glass and Excitation of Singlet Oxygen Luminescence by Energy Transfer from Chlorine Molecules

An optical absorption (OA) band of interstitial dichlorine monoxide molecules with peak at 4.7 eV and halfwidth 0.94 eV is identified in F2 laser‐irradiated (ħω = 7.9 eV) synthetic silica glass bearing both interstitial O2 and Cl2 molecules. Alongside with intrinsic defects, this OA band can contribute to solarization of silica glasses produced from SiCl4. Although only the formation of ClClO is confirmed by its Raman signature, its structural isomer ClOCl may also contribute to this induced OA band. Thermal destruction of this band between 300 °C and 400 °C almost completely restores the preirradiation concentration of interstitial Cl2. An additional weak OA band at 3.5 eV is tentatively assigned to ClO2 molecules. The strongly forbidden 1272 nm infrared luminescence band of excited singlet O2 molecules is observed at 3–3.5 eV excitation, demonstrating an energy transfer process from photoexcited triplet Cl2 to O2. The energy transfer most likely occurs between Cl2 and O2 interstitial molecules located in neighboring nanosized interstitial voids in the structure of SiO2 glass network.

Decomposition of сarbon tetrachloride under the action of a dielectric barrier discharge of atmospheric pressure in an oxygen atmosphere

In this study, the process of decomposition of carbon tetrachloride (CCl4) vapor in oxygen DBD at atmospheric pressure and its kinetic regularities have been studied. In the course of the experiments, it was shown that the efficiency of the decomposition of carbon tetrachloride in DBD can reach 100%. Depending on the conditions of the experiments, the effective rate constants were equal to (0.16–0.59) s−1, and the decomposition energy yields were (0.001–0.012) molecules per 100 eV of the inputed energy. The main decomposition products were CO2 and Cl2 molecules. The formation of a solid on the internal electrode of the reactor was also found. The substance contains atoms of carbon, oxygen, chlorine (C:O:Cl) = 1:0.38:0.01, as well as hydrogen atoms. The substance also contains functional groups –CH, –CH2, –OH and dimers of carboxylic (chlorocarboxylic) acids. Based on the solution of the Boltzmann equation for electrons, it is shown that for the compositions of a gas containing O2 molecules, ССl4, and decay products, the kinetic and transport characteristics of electrons are the same as in a pure oxygen discharge. Using the kinetic characteristics of electrons and the reaction rate constants the mechanisms of reactions leading to the found reaction products are proposed. It was shown that the primary reaction of destruction is the reaction of dissociation of CCl4 by electron impact, leading to the formation of CCl3• and Cl and the reaction with the O (1D) atom, as a result of which CCl3• and ClO• are formed.

In Situ Study of Molecular Doping of Chlorine on MoS2 Field Effect Transistor Device in Ultrahigh Vacuum Conditions.

We report a precise measurement of the sensor behavior of the field effect transistor (FET) formed with the MoS2 channel when the channel part is exposed to Cl2 gas. The gas exposure and the electrical measurement of the MoS2 FET were executed with in situ ultrahigh-vacuum (UHV) conditions in which the surface analysis techniques were equipped. This makes it possible to detect how much sensitivity the MoS2 FET can provide and understand the surface properties. With the Cl2 gas exposure to the channel, the plot of the drain current versus the gate voltage (Id–Vg curve) shifts monotonically toward the positive direction of Vg, suggesting that the adsorbate acts as an electron acceptor. The Id–Vg shifts are numerically estimated by measuring the onset of Id (threshold voltage, Vth) and the mobility as a function of the dosing amounts of the Cl2 gas. The behaviors of both the Vth shift and the mobility with the Cl2 dosing amount can be fitted with the Langmuir adsorption kinetics, which is typically seen in the uptake curve of molecule adsorption onto well-defined surfaces. This can be accounted for by a model where an impinging molecule occupies an empty site with a certain probability, and each adsorbate receives a certain amount of negative charge from the MoS2 surface up to the monolayer coverage. The charge transfer makes the Vth shifts. In addition, the mobility is reduced by the enhancement of the Coulomb scattering for the electron flow in the MoS2 channel by the accumulated charge. From the thermal desorption spectroscopy (TDS) measurement and density functional theory (DFT) calculations, we concluded that the adsorbate that is responsible for the change of the FET property is the Cl atom that is dissociated from the Cl2 molecule. The monotonic shift of Vth with the coverage suggests that the MoS2 device sensor has a good sensitivity to detect 10–3 monolayers (ML) of adsorption corresponding to the ppb level sensor with an activation time of 1 s.

Density Functional Theory Analysis of the Adsorption Behavior of C4 and Cl2 on the TiO2 (110) Surface

Based on the density functional theory (DFT) method, the behavioral mechanism of carbon addition to promote TiO2 chlorination is investigated based on the adsorption energy, charge transfer and density of states (DOS) in the coadsorption system of a C4 cluster and a Cl2 molecule on the TiO2 (110) surface. The investigated results indicate that C4 cluster bonding with an O atom on the TiO2 (110) surface could promote the Cl2 molecule to dissociate into two Cl atoms that bond with the Ti atom on the TiO2 (110) surface and a C atom of the C4 cluster. The newly formed C-O bond and Ti-Cl bond constitute the channel of electron transfer from C4 to the Cl atom and weaken the adjacent O-Ti bonding effect, which are conducive to the formation of new Ti-Cl and C-O bonds. Moreover, the tendency of C4OCl dissociation from the TiO2 (110) surface is obvious, forming oxygen vacancy defects for the next Cl atom adsorption.

Cl⋅⋅⋅Cl Halogen Bonding: Nature and Effect of Substituent at Electron Donor Cl atom

AbstractHalogen‐halogen bonding plays a vital role in crystal engineering and supramolecular chemistry. The Cl⋅⋅⋅Cl halogen bonding is studied here between R−Cl and ClF molecules using high level quantum chemical methods to find the nature and role of the substituent on the strength of this bond. A wide range of R moieties, like R=Cl, F, CH3, C2H5, C3H7, (CH3)3, H2F, CHF2, CF3, NH2, N(CH3)2, NHF and NF2, are chosen to find the effect of the substituent. The binding energies are found to range between −2.28 and −13.73 kJ mol−1 at the CCSD(T)/aug‐cc‐pVTZ level. The binding energy correlates with the negative electrostatic potential on the Cl atom and IP value of the R−Cl molecules, but it depends upon the nature of R−Cl bond. The electron density [ρ(rc)] at the bond critical point (BCP) is found to be a good parameter to assess the strength of the interaction. The decomposition of interaction energy by using Symmetry Adapted Perturbation Theory (SAPT) reveals that dispersion force is also important in stabilizing the complexes. Several important correlations between the strength of Cl⋅⋅⋅Cl interaction and molecular properties of R−Cl are established.

Multi-ionization of the Cl2 molecule in the near-infrared femtosecond laser field.

The multi-electron ionization and subsequent dissociation of the Cl2 molecule in a near-infrared femtosecond laser field was investigated via the dc-sliced ion imaging technique. The single charged molecular ions, Cl2+, dissociate from two excited states, 2Πu and 2Σg+, with the electrons ionized from the HOMO−1 and HOMO−2 orbital, respectively. For the multi-charged molecular ions, Cl2n+ (n = 2–8), our results showed that the stretch of the inter-nuclear distance benefitted the ionization of the electrons to produce highly-charged molecular ions. In addition, compared with the traditional charge resonance enhanced ionization (CREI) model, the critical distance (Rc) for the Cl2 molecule in our experiment was a short range that depended on the charge state rather than a single point.

Molecular Structure Characteristics and Wetting Behaviors of Alkyl Binary Doped Ionic Liquids’ Thin Lubricating Films on Silicon Surfaces: Molecular Dynamics Simulations

The molecular structure characteristics and wetting behaviors of alkyl binary doped ionic liquids’ (ILs) thin lubricating film on silicon surfaces, which are composed of a (DA) self-assembled monolayer (SAM) and a binary doped ILs layer, are probed by molecular dynamics simulations. In the binary doped ILs layer, 1-carboxyethyl-3-methylimidazolium chloride ([CMIM]Cl) ILs were bonded to the terminal amino (NH2) groups of the DA SAM, and 1-dodecyl-3-methylimidazolium hexafluorophosphate ([DMIM]PF6) ILs were distributed around the [CMIM]Cl molecules by physical adsorption. Additionally, surface coverage and chain grafting positions of the bonded-phase [CMIM]Cl and the adsorption properties of mobile-phase [DMIM]PF6 were investigated. The simulation results revealed that the optimal surface coverage of [CMIM]Cl on the DA SAM was 50% with a lateral spacing of 2a and a longitudinal spacing of 22a, in which a is the space between the adjacent molecules. Meanwhile, the optimal molecular ratio of [CMIM]Cl to [DMIM]PF6 was 1 : 4, leading to the stablest structure of the lubricating film. Wetting behaviors of thin lubricating film on silicon surfaces showed good hydrophobicity, which is helpful for reducing friction and adhesion. It can be anticipated that the alkyl binary doped ILs’ thin lubricating film is suitable for antifriction and antiadhesion applications on silicon surfaces.

Sulfated Tin Oxide as Highly Selective Catalyst for the Chlorination of Methane to Methyl Chloride

The chlorination of methane (CH4) is an attractive route to convert CH4 into more valuable chemicals. The selective formation of methyl chloride (CH3Cl) is a key process, but it is rather difficult to achieve with high selectivity due to a radical reaction. Catalytic ionic processes can be a solution. Herein, sulfated tin oxide (STO) was employed in the gas-phase catalytic chlorination of CH4. The STO catalyst exhibited high selectivity to CH3Cl (>96%) even at high CH4 conversion. By applying a suite of physicochemical characterizations, it is shown that the strong Lewis acid sites on STO generated by the interaction of Sn and surface sulfate groups are mainly responsible for the highly selective CH4 conversion. DFT calculations further revealed that STO surface can activate more Cl2 molecules in a heterolytic manner, leading to better catalytic performances as compared to SnO2 and sulfated zirconia catalysts.