Synthesis and Characterization of Phosphate‐Catecholate Chelated Nd(III), Zr(IV), and Al(III) Complexes

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Synthesis and Characterization of Phosphate-Catecholate Chelated Nd(III), Zr(IV), and Al(III) Complexes

Alkoxyphosphoranes, Ph2P(OR)(O2C6Cl4) and the metal chlorides generate corresponding phosphate-catecholate chelated Nd(III), Zr(IV) and Al(III) chlorides via ethyl chloride elimination. These monometallic and bimetallic metal complexes are stabilized by chelating P−O and catecholate-O donors.


Abstract

Metal phosphates are important catalysts and materials in synthesis chemistry. Herein, we describe the synthesis and characterization of phosphate-catecholate chelated Nd(III), Zr(IV) and Al(III) chlorides (2–5). These species are achieved via ethyl chloride elimination reaction of oxophosphoranes with corresponding metal chlorides. The product 2–5 represent a new serial of monometallic and bimetallic phosphate-catecholate chelated metal complexes stabilized by both P−O and catecholate-O donors. These findings pave the way for future explorations of such species in catalysis.

Acute Toxicity of Copper to Three Species of Pacific Salmon Fry in Water with Low Hardness and Low Dissolved Organic Carbon

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Abstract

Proposed development of a mine within Alaska's Bristol Bay watershed (USA) has raised concerns about the potential impact of copper (Cu) on Pacific salmon (Oncorhynchus spp.). We conducted 96-h flow-through bioassays using low-hardness and low dissolved organic carbon water to determine the acute lethal toxicity of Cu to sockeye (Oncorhynchus nerka), Chinook (Oncorhynchus tshawytscha), and coho salmon (Oncorhynchus kisutch) fry. We aimed to determine Cu toxicity under field-relevant water quality conditions and to assess three methods of calculating ambient Cu criteria: the biotic ligand model (BLM), a multiple linear regression model endorsed by the US Environmental Protection Agency, and the hardness-based model currently used by the State of Alaska. The criteria generated by all models were below 20% lethal Cu concentrations by factors ranging from 2.2 to 54.3, indicating that all criteria would be protective against mortality. The multiple linear regression-based criteria were the most conservative and were comparable to BLM-based criteria. The median lethal concentrations (LC50s) for sockeye, Chinook, and coho were 35.2, 23.9, and 6.3 µg Cu/L, respectively. We also used the BLM to predict LC50s for each species. Model predictions differed from empirical LC50s by factors of 0.7 for sockeye and Chinook salmon, and 1.1 for coho salmon. These differences fell within the acceptable range of ±2, indicating the model's accuracy. We calculated critical lethal Cu accumulation values for each species to account for differing water chemistry in each bioassay; the present study revealed that coho salmon were most sensitive to Cu, followed by sockeye and Chinook salmon. Our findings underscore the importance of considering site- and species-specific factors when modeling Cu toxicity. The empirical data we present may enhance Cu risk assessments for Pacific salmon. Environ Toxicol Chem 2023;00:1–13. © 2023 SETAC

Revisiting the structure and dynamics of hydrated Cd2+ in aqueous solutions: Insights from the RI‐SCS‐MP2/MM molecular dynamics simulation

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Revisiting the structure and dynamics of hydrated Cd2+ in aqueous solutions: Insights from the RI-SCS-MP2/MM molecular dynamics simulation

The MP2 QM/MM MD simulation revealed that Cd2+ is coordinated with mostly six water molecules in the first hydration shell with numerous ligand exchange events during the simulation time of 200 ps.


Abstract

The spin component scale MP2/molecular mechanics molecular dynamics simulation investigated the hydration shell formation and hydrated Cd2+ dynamics in the water environment. At the first hydration shell, six water molecules with 2.27 Å for the average distance between water and Cd2+. Dynamical properties were analyzed by computing the water molecule's mean residence time (MRT) in its first and second hydration shells. The MRT of each shell was determined to be 31.8 and 1.92 ps, suggesting the strong influence of Cd2+ in the first hydration shell. The second shell was labile, with an average number of water molecules being 18. Despite the strong interaction between Cd2+ and water molecules in the first shell, the influence of ions in the second hydration shell remained weak.

Agricultural Use of Insecticides Alters Homeostatic Behaviors and Cognitive Ability in Lymnaea stagnalis

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Abstract

Lymnaea stagnalis is an ecologically important, stress-sensitive, freshwater mollusk that is at risk for exposure to insecticides via agricultural practices. We provide insight into the impact insecticides have on L. stagnalis by comparing specific behaviors including feeding, locomotion, shell regeneration, and cognition between snails collected at two different sites: one contaminated by insecticides and one not. We hypothesized that each of the behaviors would be altered in the insecticide-exposed snails and that similar alterations would be induced when control snails were exposed to the contaminated environment. We found no significant differences in locomotion, feeding, and shell regeneration of insecticide-exposed L. stagnalis compared with nonexposed individuals. Significant changes in feeding and shell repair were observed in nonexposed snails inhabiting insecticide-contaminated pond water. Most importantly, snails maintained and trained in insecticide-contaminated pond water did not form configural learning, but this cognitive deficit was reversed when these snails were maintained in insecticide-free pond water. Our findings conclude that insecticides have a primarily negative impact on this higher form of cognition in L. stagnalis. Environ Toxicol Chem 2023;00:1–12. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Comprehensive investigation of electronic structure, phonon spectrum and thermoelectric performance of LuMSb (M = Ni, Pd, Pt) half Heusler compounds from first principles

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Abstract

We studied the structural, electronic, phonon spectrum and thermoelectric properties of ternary LuMSb (M = Ni, Pd, Pt) half Heusler compounds by using first principles method. The electronic properties are calculated via energy band structure and density of states by using GGA + U approximation. The calculations reveal that the replacement of Ni with Pd and Pt, energy gap decreases and LuNiSb, LuPdSb are found to have narrow indirect band gaps and exhibit semiconducting nature, while LuPtSb is found to be a gapless semiconductor. Phonon band structure calculations give only positive values of phonon frequency indicating the dynamically stability of these compounds. The thermoelectric properties have been computed using semi-classical Boltzmann transport theory. We found high Seebeck coefficient (S) and high power factor (PF) for LuNiSb and LuPdSb compounds in the whole temperature range. The ZT values of LuNiSb and LuPdSb are high in general and reach a maximum of 0.67 and 0.69 at 450 K, respectively, whereas 0.39 is the maximum ZT value for LuPtSb at the same temperature. These findings propose LuNiSb and LuPdSb compounds as promising materials for thermoelectric applications at room temperature.

Bond dissociation energies of the fifth‐row elements (InI): A quantum theoretical benchmark study

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Bond dissociation energies of the fifth-row elements (In<span class='icomoon'></span>I): A quantum theoretical benchmark study

Compounds containing fifth-row elements, such as In, Sn, Sb, Te, and I, present a challenge to computational chemistry. The BDE of these compounds were calculated using ab-initio methods, including some popular DFT functionals, as well as MP2 and CCSD(T). The top-performing functionals were MN12SX, MN15L, B3P86, and M062X.


Abstract

The bond dissociation energies (BDE) of most main-group elements have been accurately measured. However, the BDE values for heavy elements, particularly those from the fifth period (InI), are still missing or poorly validated. This study aims to identify the most accurate computational methods for calculating BDE values of compounds containing fifth-row elements, including In, Sn, Sb, Te, and I, with a focus on readily accessible methods in software packages. The investigation involved a benchmark study using density functional theory (DFT), in addition to the 2nd order Møller–Plesset perturbation theory (MP2) and the coupled cluster with single, double, and perturbative triple excitations CCSD(T). The DFT functionals used in the study include APFD, B3LYP, B3LYP-D3, B3P86, B97-D3, BHandH, HSEH1PBE, M06-2X, MN12-SX, MN15-L, and TPSSH. The functionals were carefully selected to cover some popular functionals as well as to cover all levels of the Jacob's ladder of DFT accuracy. The computed BDE values were compared with experimental values, and the results were filtered to remove any possible outliers. The statistical errors (MAPE, RMSE, and Pearson's) were then calculated and used to assess the performance of the methods.

Study on the microscopic mechanism of adsorption and diffusion of hydrocarbon oil drops on coal surface using molecular dynamics simulations

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Study on the microscopic mechanism of adsorption and diffusion of hydrocarbon oil drops on coal surface using molecular dynamics simulations

Spreading characteristics of hydrocarbon oil drops on coal surfaces.


Abstract

Flotation of fine coal particles usually uses oil collectors, but the micromechanisms need to be more refined due to the complex structure and abundant functional groups on the surface of coal bodies. The adsorption spreading behavior and interfacial properties of nonpolar oil drops on flat low-order coal (LOC) and high-order coal (HOC) surfaces were investigated in depth using molecular dynamics (MD) simulations, while the effects of different functional groups on LOC surfaces were also considered. The results showed that the contact angle, contact area and interaction energy of oil drops adsorbed on the LOC and HOC surfaces at simulated equilibrium in aqueous environment were 77.68°, 621.49 Å2, −140.94 kcal/mol; 53.98°, 962.14 Å2, and −195.13 kcal/mol, respectively. The smaller the equilibrium contact angle between the oil drops and the surface, the larger the contact area and the larger the absolute value of the interaction energy, the better the spreading effect of the oil drops and the easier the surface is to flotation. Compared with the HOC surface, the oil drops could not displace the water molecules on the LOC surface better and spread poorly on its surface, and the migration rate was higher. This was caused by the abundant functional groups on the surface of LOC. The type of functional group significantly affects the interaction of nonpolar oil drops with hydrophilic surfaces, with the order of adsorption strength being CH3 > COCH3 > OH > COOH. The formation of a dense hydrated film of oil drops on the COOH surface was an important reason for the difficulty of flotation on the LOC surface. MD elucidated the mechanism of action of nonpolar oil collectors on LOC and HOC surfaces, which is a guide for efficient flotation on LOC surfaces.