Polyoxometalate-Incorporated CuI-Resorcin[4]arene Metal-Organic Complexes as Heterogeneous Catalysts for Catalytic Oxidation of Mustard Gas Simulant

Exploring efficient heterogeneous catalysts for catalytic oxidation of chemical warfare agents (CWAs) is highly desired. As a class of discrete anionic metal oxide clusters, polyoxometalates (POMs) provide abundant catalytic active sites, thus resulting their rich redox properties. Here, a family of known POM-incorporated Cu^I-resorcin[4]arene metal-organic complexes, namely, [Cu₄(TPTR4A)₂][PW₁₂O₄₀](OH) ⋅ 0.5DMA ⋅ 5H₂O ( Cu - PW ), [Cu₄(TPTR4 A)₂][PMo₁₂O₄₀](OH) ⋅ 2DMA ⋅ H₂O ( Cu - PMo ) and [Cu₄(TPTR4A)₂][SiW₁₂O₄₀] ⋅ 2.5DMA ( Cu - SiW ) were utilized as catalysts to promote the oxidation of 2-chloroethyl ethyl sulfide (CEES). Strikingly, compared to the novel compound [Cu₃Cl₆(TPTR4A)(DMA)] ⋅ CH₃CH₂OH (defined as Cu - T ), the three complexes exhibited excellent stability, indicating that the integration of POMs and metal–organic units could improve the stability of the compounds. Moreover, Cu - PMo and Cu - PW showed higher activities for the catalytic oxidation of CEES to CEESO with selectivities both of 99 %.     

Enhanced Interfacial Electron Transfer by Asymmetric Cu-Ov-In Sites on In2O3 for Efficient Peroxymonosulfate Activation

Enhancing the peroxymonosulfate (PMS) activation efficiency to generate more radicals is vital to promote the Fenton-like reaction activity, however, how to promote the PMS adsorption and accelerate the interfacial electron transfer to boost its activation kinetics remains a great challenge. Herein, we prepared Cu-doped defect-rich In₂O₃ (Cu-In₂O₃/O_v) catalysts containing asymmetric Cu−O_v−In sites for PMS activation in water purification. The intrinsic catalytic activity is that the side-on adsorption configuration of the O−O bond (Cu−O−O−In) at the Cu-O_v-In sites significantly stretches the O−O bond length. Meanwhile, the Cu-O_v-In sites increase the electron density near the Fermi energy level, promoting more and faster electron transfer to the O−O bond for generating more SO₄⋅⁻ and ⋅OH. The degradation rate constant of tetracycline achieved by Cu-In₂O₃/O_v is 31.8 times faster than In₂O₃/O_v, and it shows the possibility of membrane reactor for practical wastewater treatment.     

C−H Activation by Iron-Vanadium Bimetallic Oxide Cluster Anions FeV3O10− and FeV5O15−: A Comparison with Scandium-Vanadium Oxide Clusters

Late transition metal-bonded atomic oxygen radicals (LTM−O⋅⁻) have been frequently proposed as important active sites to selectively activate and transform inert alkane molecules. However, it is extremely challenging to characterize the LTM−O⋅⁻-mediated elementary reactions for clarifying the underlying mechanisms limited by the low activity of LTM−O⋅⁻ radicals that is inaccessible by the traditional experimental methods. Herein, benefiting from our newly-designed ship-lock type reactor, the reactivity of iron-vanadium bimetallic oxide cluster anions FeV₃O₁₀⁻ and FeV₅O₁₅⁻ featuring with Fe−O⋅⁻ radicals to abstract a hydrogen atom from C₂−C₄ alkanes has been experimentally characterized at 298 K, and the rate constants are determined in the orders of magnitude of 10⁻¹⁴ to 10⁻¹⁶ cm³ molecule⁻¹ s⁻¹, which are four orders of magnitude slower than the values of counterpart ScV₃O₁₀⁻ and ScV₅O₁₅⁻ clusters bearing Sc−O⋅⁻ radicals. Theoretical results reveal that the rearrangements of the electronic and geometric structures during the reaction process function to modulate the activity of Fe−O⋅⁻. This study not only quantitatively characterizes the elementary reactions of LTM−O⋅⁻ radicals with alkanes, but also provides new insights into structure-activity relationship of M−O⋅⁻ radicals.     

Highly Stable Copper(I)–Thiacalix[4]arene-Based Frameworks for Highly Efficient Catalysis of Click Reactions in Water

Environmentally friendly metal–organic frameworks (MOFs) have gained considerable attention for their potential use as heterogeneous catalysts. Herein, two Cu^I-based MOFs, namely, [Cu₄Cl₄L] ⋅ CH₃OH ⋅ 1.5 H₂O ( 1-Cl ) and [Cu₄Br₄L] ⋅ DMF ⋅ 0.5 H₂O ( 1-Br ), were assembled with new functionalized thiacalix[4]arenes (L) and halogen anions X⁻ (X=Cl and Br) under solvothermal conditions. Remarkably, catalysts 1-Cl and 1-Br exhibit great stability in aqueous solutions over a wide pH range. Significantly, MOFs 1-Cl and 1-Br , as recycled heterogeneous catalysts, are capable of highly efficient catalysis for click reactions in water. The MOF structures, especially the exposed active Cu^I sites and 1D channels, play a key role in the improved catalytic activities. In particular, their catalytic activities in water are greatly superior to those in organic solvents or even in mixed solvents. This work proposes an attractive route for the design and self-assembly of environmentally friendly MOFs with high catalytic activity and reusability in water.     

Rapid Ozone Decomposition over Water-activated Monolithic MoO3/Graphdiyne Nanowalls under High Humidity

Catalytic ozone (O₃) decomposition at high relative humidity (RH) remains a great challenge due to the catalysts poison and deactivation under high humidity. Here, we firstly elaborate the role of water activation and the corresponding mechanism of the promoted O₃ decomposition over the three-dimensional monolithic molybdenum oxide/graphdiyne (MoO₃/GDY) catalyst. The O₃ decomposition over MoO₃/GDY reaches up to 100 % under high humid condition (75 % RH) at room temperature, which is 4.0 times as high as that of dry conditions, significantly surpasses other carbon-based MoO₃ materials(≤7.1 %). The sp-hybridized carbon in GDY donates electrons to MoO₃ along the C−O−Mo bond, facilitating water activation to form hydroxyl species. As a result, hydroxyl species dissociated from water act as new active sites, promoting the adsorption of O₃ and the generation of new intermediate species (hydroxyl ⋅OH and superoxo ⋅O₂⁻), which significantly lowers the energy barriers of O₃ decomposition (0.57 eV lower than dry conditions).     

Observation of Transition-Metal–Boron Triple Bonds in IrB2O− and ReB2O−

Multiple bonds between boron and transition metals are known in many borylene (:BR) complexes via metal d_π→BR back-donation, despite the electron deficiency of boron. An electron-precise metal–boron triple bond was first observed in BiB₂O⁻ [Bi≡B−B≡O]⁻ in which both boron atoms can be viewed as sp-hybridized and the [B−BO]⁻ fragment is isoelectronic to a carbyne (CR). To search for the first electron-precise transition-metal-boron triple-bond species, we have produced IrB₂O⁻ and ReB₂O⁻ and investigated them by photoelectron spectroscopy and quantum-chemical calculations. The results allow to elucidate the structures and bonding in the two clusters. We find IrB₂O⁻ has a closed-shell bent structure (C_s, ¹A′) with BO⁻ coordinated to an Ir≡B unit, (⁻OB)Ir≡B, whereas ReB₂O⁻ is linear (C_∞v, ³Σ⁻) with an electron-precise Re≡B triple bond, [Re≡B−B≡O]⁻. The results suggest the intriguing possibility of synthesizing compounds with electron-precise M≡B triple bonds analogous to classical carbyne systems.     

Solvent-Vapor-Induced Reversible Single-Crystal-to-Single-Crystal Transformation of a Triphosphaazatriangulene-Based Metal–Organic Framework

A triphosphaazatriangulene (H₃L) was synthesized through an intramolecular triple phospha-Friedel–Crafts reaction. The H₃L triangulene contains three phosphinate groups and an extended π-conjugated framework, which enables the stimuli-responsive reversible transformation of [Cu(HL)(DMSO)⋅(MeOH)]_n, a 3D-MOF that exhibits reversible sorption characteristics, into (H₃L⋅0.5 [Cu₂(OH)₄⋅6 H₂O] ⋅4 H₂O), a 1D-columnar assembled proton-conducting material. The hydrophilic nature of the latter resulted in a proton conductivity of 5.5×10⁻³ S cm⁻¹ at 95 % relative humidity and 60 °C.     

Synthesis of Ti(OH)OF ⋅ 0.66 H2O in Imidazolium-based Ionic Liquids

The influence of the cation of imidazolium-derived ionic liquids (ILs) on a low-temperature solution-based synthesis of hexagonal tungsten bronze (HTB) type Ti(OH)OF ⋅ 0.66 H₂O and bronze-type TiO₂(B) is investigated. The IL (C_xmim BF₄) acts as solvent and also as reaction partner with respect to the decomposition of [BF₄]⁻, releasing F⁻. In the present study, the chain length of the alkyl chain side groups attached to the imidazolium ring was varied (C₂mim BF₄ to C₁₀mim BF₄), and the obtained solids were analyzed by Powder X-Ray diffraction (PXRD) followed by Rietveld refinement. As a main finding these analyses indicate a transformation of Ti(OH)OF ⋅ 0.66 H₂O into TiO₂(B), and upon prolonged reaction time finally also into anatase TiO₂. Rietveld analysis suggests that when using ILs with longer alkyl chains, the conversion of Ti(OH)OF ⋅ 0.66 H₂O is slower compared to syntheses performed with smaller alkyl chains. Hence, Ti(OH)OF ⋅ 0.66 H₂O appears to be metastable and is stabilized by long-chain ILs serving as surfactant attached to the crystallites’ surface. In this view, the ILs shield the nanoparticles and thus slow down the conversion into the more stable compounds. This confirms previous findings that ILs act as both, solvent and reaction medium in this reaction, thus enabling the synthesis of peculiar Ti-oxides.     

Self-Assembly of Polyoxometalate-Resorcin[4]arene-Based Inorganic-Organic Complexes: Metal Ion Effects on the Electrochemical Performance of Lithium Ion Batteries

With their adjustable structures and diverse functions, polyoxometalate (POM)-resorcin[4]arene-based inorganic–organic complexes are a kind of potential multifunctional material. They have potential applications for lithium ion batteries (LIBs). However, the relationship between different coordinated metal ions and electrochemical performance has rarely been investigated. Here, three functionalized POM-resorcin[4]arene-based inorganic–organic materials, [Co₂(TMR4 A)₂(H₂O)₁₀][SiW₁₂O₄₀] ⋅ 2 EtOH ⋅ 4.5 H₂O ( 1 ), [Ni₂(TMR4 A)₂(H₂O)₁₀][SiW₁₂O₄₀] ⋅ 4 EtOH ⋅ 13 H₂O ( 2 ), and [Zn₂(TMR4 A)₂(H₂O)₁₀][SiW₁₂O₄₀] ⋅ 2 EtOH ⋅ 2 H₂O ( 3 ), have been synthesized. Furthermore, to enhance the conductivities of these compounds, 1–3 were doped with reduced graphene oxide (RGO) to give composites 1 @RGO- 3 @RGO, respectively. As anode materials for LIBs, 1 @RGO- 3 @RGO can deliver very high discharge capacities (1445.9, 1285.0 and 1095.3 mAh g⁻¹, respectively) in the initial run, and show discharge capacities of 898, 665 and 651 mAh g⁻¹, respectively, at a current density of 0.1 A g⁻¹ over 100 runs. More importantly, the discharge capacities of 319, 283 and 329 mAh g⁻¹ were maintained for 1 @RGO- 3 @RGO even after 400 cycles at large current density (1 A g⁻¹).     

Complexation and Versatile Reactivity of a Highly Lewis Acidic Cationic Mg Complex with Alkynes and Phosphines

[(BDI)Mg⁺][B(C₆F₅)₄⁻] ( 1 ; BDI=CH[C(CH₃)NDipp]₂; Dipp=2,6-diisopropylphenyl) was prepared by reaction of (BDI)MgnPr with [Ph₃C⁺][B(C₆F₅)₄⁻]. Addition of 3-hexyne gave [(BDI)Mg⁺ ⋅ (EtC≡CEt)][B(C₆F₅)₄⁻]. Single-crystal X-ray analysis, NMR investigations, Raman spectra, and DFT calculations indicate a significant Mg-alkyne interaction. Addition of the terminal alkynes PhC≡CH or Me₃SiC≡CH led to alkyne deprotonation by the BDI ligand to give [(BDI-H)Mg⁺(C≡CPh)]₂ ⋅ 2 [B(C₆F₅)₄⁻] ( 2 , 70 %) and [(BDI-H)Mg⁺(C≡CSiMe₃)]₂ ⋅ 2 [B(C₆F₅)₄⁻] ( 3 , 63 %). Addition of internal alkynes PhC≡CPh or PhC≡CMe led to [4+2] cycloadditions with the BDI ligand to give {Mg⁺C(Ph)=C(Ph)C[C(Me)=NDipp]₂}₂ ⋅ 2 [B(C₆F₅)₄⁻] ( 4 , 53 %) and {Mg⁺C(Ph)=C(Me)C[C(Me)=NDipp]₂}₂ ⋅ 2 [B(C₆F₅)₄⁻] ( 5 , 73 %), in which the Mg center is N,N,C-chelated. The (BDI)Mg⁺ cation can be viewed as an intramolecular frustrated Lewis pair (FLP) with a Lewis acidic site (Mg) and a Lewis (or Brønsted) basic site (BDI). Reaction of [(BDI)Mg⁺][B(C₆F₅)₄⁻] ( 1 ) with a range of phosphines varying in bulk and donor strength generated [(BDI)Mg⁺ ⋅ PPh₃][B(C₆F₅)₄⁻] ( 6 ), [(BDI)Mg⁺ ⋅ PCy₃][B(C₆F₅)₄⁻] ( 7 ), and [(BDI)Mg⁺ ⋅ PtBu₃][B(C₆F₅)₄⁻] ( 8 ). The bulkier phosphine PMes₃ (Mes=mesityl) did not show any interaction. Combinations of [(BDI)Mg⁺][B(C₆F₅)₄⁻] and phosphines did not result in addition to the triple bond in 3-hexyne, but during the screening process it was discovered that the cationic magnesium complex catalyzes the hydrophosphination of PhC≡CH with HPPh₂, for which an FLP-type mechanism is tentatively proposed.     

Regulating Spin Polarization through Cationic Vacancy Defects in Bi4Ti3O12 for Enhanced Molecular Oxygen Activation

Molecular oxygen (O₂) activation technology is of great significance in environmental purification due to its eco-friendly operation and cost-effective nature. However, the activation of O₂ is limited by spin-forbidden transitions, and efficient molecular oxygen activation depends on electronic behavior and surface adsorption. Herein, we prepared cationic defect-rich Bi₄Ti₃O₁₂ (BTO-MV2) catalysts containing Ti vacancies (V_Ti) for O₂ activation in water purification. The V_Ti on BTO nanosheets can induce electron spin polarization, increasing the number of spin-down photogenerated electrons and reducing the recombination of electron-hole pairs. An active surface V_Ti is also formed, serving as a center for adsorbing O₂ and extracting electrons, effectively generating ⋅OH, O₂⋅⁻ and ¹O₂. The degradation rate constant of tetracycline achieved by BTO-MV2 is 3.3 times faster than BTO, indicating a satisfactory prospect for practical application. This work provides an efficient pathway to activate molecular oxygen by constructing new active sites through cationic vacancy modification technology.     

Dual-Plasmon Resonance Coupling Promoting Directional Photosynthesis of Nitrate from Air

Photocatalysis, particularly plasmon-mediated photocatalysis, offers a green and sustainable approach for direct nitrogen oxidation into nitrate under ambient conditions. However, the unsatisfactory photocatalytic efficiency caused by the limited localized electromagnetic field enhancement and short hot carrier lifetime of traditional plasmonic catalysts is a stumbling block to the large-scale application of plasmon photocatalytic technology. Herein, we design and demonstrate the dual-plasmonic heterojunction (Bi/Cs_xWO₃) achieves efficient and selective photocatalytic N₂ oxidation. The yield of NO₃⁻ over Bi/Cs_xWO₃ (694.32 μg g⁻¹ h⁻¹) are 2.4 times that over Cs_xWO₃ (292.12 μg g⁻¹ h⁻¹) under full-spectrum irradiation. The surface dual-plasmon resonance coupling effect generates a surge of localized electromagnetic field intensity to boost the formation efficiency and delay the self-thermalization of energetic hot carriers. Ultimately, electrons participate in the formation of ⋅O₂⁻, while holes involve in the generation of ⋅OH and the activation of N₂. The synergistic effect of multiple reactive oxygen species drives the direct photosynthesis of NO₃⁻, which achieves the overall-utilization of photoexcited electrons and holes in photocatalytic reaction. The concept that the dual-plasmon resonance coupling effect facilitates the directional overall-utilization of photoexcited carriers will pave a new way for the rational design of efficient photocatalytic systems.     

Electrical Pulse-Driven Periodic Self-Repair of Cu-Ni Tandem Catalyst for Efficient Ammonia Synthesis from Nitrate

Electrocatalytic nitrate reduction sustainably produces ammonia and alleviates water pollution, yet is still challenging due to the kinetic mismatch and hydrogen evolution competition. Cu/Cu₂O heterojunction is proven effective to break the rate-determining NO₃⁻-to-NO₂⁻ step for efficient NH₃ conversion, while it is unstable due to electrochemical reconstruction. Here we report a programmable pulsed electrolysis strategy to achieve reliable Cu/Cu₂O structure, where Cu is oxidized to CuO during oxidation pulse, then regenerating Cu/Cu₂O upon reduction. Alloying with Ni further modulates hydrogen adsorption, which transfers from Ni/Ni(OH)₂ to N-containing intermediates on Cu/Cu₂O, promoting NH₃ formation with a high NO₃⁻-to-NH₃ Faraday efficiency (88.0±1.6 %, pH 12) and NH₃ yield rate (583.6±2.4 μmol cm⁻² h⁻¹) under optimal pulsed conditions. This work provides new insights to in situ electrochemically regulate catalysts for NO₃⁻-to-NH₃ conversion.     

Structurally Stable Ni(OH)2 Composite with Super Long-term Cycling Life for Aqueous High-performance Supercapacitor

We synthesized an electrochemical structurally stable composite electrode, containing Ni-doped Co(CO₃)_0.5OH ⋅ 0.11H₂O nanoneedles and nanoflake-/nanofrustum-like Ni(OH)₂ with highly hydrophilic group, leading to enhanced rare performance. The electrode exhibits an outstanding ultra-long cycle life of more than 140,000 cycles. Specially, the assembled aqueous hybrid supercapacitor presents more than 80 % capacity retention even after 170,000 cycles and high energy density of 44.5 Wh kg⁻¹. This work highlights a feasible strategy to design and develop high-efficiency electrodes via engineering on composition and nanostructure.     

Dual-Templating Approaches to Soybeans Milk-Derived Hierarchically Porous Heteroatom-Doped Carbon Materials for Lithium-Ion Batteries

Biomass derived carbon materials are widely available, cheap and abundant resources. The application of these materials as electrodes for rechargeable batteries shows great promise. To further explore their applications in energy storage fields, the structural design of these materials has been investigated. Hierarchical porous heteroatom-doped carbon materials (HPHCs) with open three-dimensional (3D) nanostructure have been considered as highly efficient energy storage materials. In this work, biomass soybean milk is chosen as the precursor to construct N, O co-doped interconnected 3D porous carbon framework via two approaches by using soluble salts (NaCl/Na₂CO₃ and ZnCl₂/Mg₅(OH)₂(CO₃)₄, respectively) as hard templates. The electrochemical results reveal that these structures were able to provide a stable cycling performance (710 mAh ⋅ g⁻¹ at 0.1 A ⋅ g⁻¹ after 300 cycles for HPHC-a, and 610 mAh ⋅ g⁻¹ at 0.1 A ⋅ g⁻¹ after 200 cycles for HPHC-b) in Li-ion battery and Na-ion storage (210 mAh ⋅ g⁻¹ at 0.1 A ⋅ g⁻¹ after 900 cycles for HPHC-a) as anodes materials, respectively. Further comparative studies showed that these improvements in HPHC-a performance were mainly due to the honeycomb-like structure containing graphene-like nanosheets and high nitrogen content in the porous structures. This work provides new approaches for the preparation of hierarchically structured heteroatom-doped carbon materials by pyrolysis of other biomass precursors and promotes the applications of carbon materials in energy storage fields.     

Determination of Cu2+ in Drinking Water Based on Electrochemiluminescence of Ru(phen)32+ and Cyclam

A convenient and simple electrochemiluminescence (ECL) method was employed to detect trace amounts of Cu²⁺ in drinking water. This method is based on the inhibitory effect of Cu²⁺ on the ECL of Ru(phen)₃²⁺ and 1,4,8,11‐tetraazacyclotetradecane (cyclam) system. ECL intensity of Ru(phen)₃²⁺ was considerably enhanced by the addition of cyclam because of the ECL reaction between them. The ECL intensity of Ru(phen)₃²⁺/cyclam system rapidy decreased with the addition Cu²⁺ because of the formation of chelate complex [Cu(cyclam)]²⁺. Good linear response (R ²=0.9948) was obtained at Cu²⁺ concentration of 1.0×10⁻⁹−1.0×10⁻⁵ mol ⋅ L⁻¹ at glassy carbon electrode in 0.1 mol ⋅ L⁻¹ phosphate buffer (pH 9.0). Observed detection limit of 4.8×10⁻¹⁰ mol ⋅ L⁻¹ satisfied the maximum contaminant level goal (MCLG) for Cu²⁺ set by the US Environmental Protection Agency (US EPA). Applicability of the proposed method was verified by the good reproducibility and stability of the method when applied to determine Cu²⁺ in tap water and simulated wastewater. Thus, a novel ECL detection method was developed for Cu²⁺ detection.     

Synthesis of Non-precious N-doped Mesoporous Fe3O4/CoO@NC Materials towards Efficient Oxygen Reduction Reaction for Microbial Fuel Cells

N-doped transition metal oxides are strategic materials towards the efficient oxygen reduction reaction (ORR) of microbial fuel cells (MFCs). Non-precious N-doped Fe₃O₄/CoO@NC−T (T represents carbonization temperature) catalysts are prepared by an efficient two-step strategy for ORR. Fe₃O₄/CoO@NC-750 exhibits the best performance with an efficient four-electron transfer pathway. The optimal power density of MFCs by using Fe₃O₄/CoO@NC-750 as the cathode catalyst (1243.4 mW ⋅ m⁻²) is superior to that of the MFCs with commercial Pt/C catalyst (1080 mW ⋅ m⁻²), which shows an outstanding activity towards ORR. No significant decrease in output voltage results over 70 days, which shows an excellent electrochemical stability.     

Photo-thermal Cooperative Carbonylation of Ethanol with CO2 on Cu2O-SrTiCuO3-x

Carbonylation of ethanol with CO₂ as carbonyl source into value-added esters is of considerable significance and interest, while remains of great challenge due to the harsh conditions for activation of inert CO₂ in that the harsh conditions result in undesired activation of α-C−H and even cleavage of C−C bond in ethanol to deteriorate the specific activation of O−H bond. Herein, we propose a photo-thermal cooperative strategy for carbonylation of ethanol with CO₂, in which CO₂ is activated to reactive CO via photo-catalysis with the assistance of *H from thermally-catalyzed dissociation of alcoholic O−H bond. To achieve this proposal, an interfacial site and oxygen vacancy both abundant SrTiCuO_3-x supported Cu₂O (Cu₂O-SrTiCuO_3-x) has been designed. A production of up to 320 μmol g⁻¹ h⁻¹ for ethyl formate with a selectivity of 85.6 % to targeted alcoholic O−H activation has been afforded in photo-thermal assisted gas-solid process under 3.29 W cm⁻¹ of UV/Vis light irradiation (144 °C) and 0.2 MPa CO₂. In the photo-driven activation of CO₂ and following carbonylation, CO₂ activation energy decreases to 12.6 kJ mol⁻¹, and the cleavage of alcoholic α-C−H bond has been suppressed.     

Theoretical Study of the Hydroxyl-Radical-Initiated Degradation Mechanism,Kinetics, and Subsequent Evolution of Methyl and Ethyl Iodides in the Atmosphere

The degradation and transformation of iodinated alkanes are crucial in the iodine chemical cycle in the marine boundary layer. In this study, MP2 and CCSD(T) methods were adopted to study the atmospheric transformation mechanism and degradation kinetic properties of CH₃I and CH₃CH₂I mediated by ⋅OH radical. The results show that there are three reaction mechanisms including H-abstraction, I-substitution and I-abstraction. The H-abstraction channel producing ⋅CH₂I and CH₃C ⋅ HI radicals are the main degradation pathways of CH₃I and CH₃CH₂I, respectively. By means of the variational transition state theory and small curvature tunnel correction method, the rate constants and branching ratios of each reaction are calculated in the temperature range of 200–600 K. The results show that the tunneling effect contributes more to the reaction at low temperatures. Theoretical reaction rate constants of CH₃I and CH₃CH₂I with ⋅OH are calculated to be 1.42×10⁻¹³ and 4.44×10⁻¹³ cm³ molecule⁻¹ s⁻¹ at T=298 K, respectively, which are in good agreement with the experimental values. The atmospheric lifetimes of CH₃I and CH₃CH₂I are evaluated to be 81.51 and 26.07 day, respectively. The subsequent evolution mechanism of ⋅CH₂I and CH₃C ⋅ HI in the presence of O₂, NO and HO₂ indicates that HCHO, CH₃CHO, and I-atom are the main transformation end-products. This study provides a theoretical basis for insight into the diurnal conversion and environmental implications of iodinated alkanes.     

A New Approach for the Voltammetric Determination of Amoxicillin in the Dosage Form Using Azo Coupling Reaction with Sulphanilamide

The novel method of amoxicillin (AM) determination has been developed using single-sweep polarography. The proposed method is based on the obtaining of yellow coloured azo compound due to azo coupling reaction of previous diazotized sulphanilamide (SA) (in the medium of 0.6 M hydrochloric acid) with amoxicillin at pH=9.0 with the further reduction of the formed analytical form on a dropping mercury electrode. Voltammetric determination of amoxicillin is carried out due to the reduction peak of azo group of the obtained azo compound in the presence of 0.05 mol ⋅ L⁻¹ Na₂B₄O₇ as a background electrolyte at the potential E_c^p2=−0.55 V and potential sweep rate of 2.5 V ⋅ s⁻¹. The developed voltammetric method has two linear ranges of the determined concentrations (0.05–2.0) ⋅ 10⁻⁵ mol ⋅ L⁻¹ and (0.2–1.0) ⋅ 10⁻⁴ mol ⋅ L⁻¹ and the high sensitivity: LOD without the removing of unreacted sodium nitrite is 1.1 ⋅ 10⁻⁶ mol ⋅ L⁻¹, and 7.2 ⋅ 10⁻⁷ mol ⋅ L⁻¹, when NaNO₂ excess is removed using urea. The developed voltammetric technique of AM determination has been approved during the analyses of tablets and oral suspension.