Monthly Archives: September 2023

Assessing the Toxicity of Sea Salt to Early Life Stages of Freshwater Mussels: Implications for Sea Level Rise in Coastal Rivers

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Abstract

Sea levels across the planet are rising, particularly along the eastern coast of the United States. Climate-induced sea level rise can result in the inundation and intrusion of seawater into freshwater drainages. This would alter salinity regimes and lead to the salinization of coastal freshwater ecosystems. Increased salinity levels in freshwater can negatively affect freshwater-dependent species, including native mussels belonging to the order Unionida, which are highly sensitive to changes in water quality. Sea salt is largely made up of sodium and chloride ions, forming sodium chloride, a known toxicant to freshwater mussels. However, sea salt is a mixture that also contains other major ions, including potassium, sulfate, calcium, strontium, and magnesium, among others. Freshwater mussels exposed to sea salt would be exposed to each of the sea salt ions at the same time, resulting in a mixture toxicity effect. The mixture toxicity of these ions on early life stages of freshwater mussels is largely unknown because most research to date has evaluated individual salt ions in relative isolation. Therefore, we conducted acute toxicity tests on early life stages (glochidia and juvenile) of three freshwater mussel species that inhabit Atlantic Slope drainages (nonsalinity-adapted Atlanticoncha ochracea, salinity-adapted A. ochracea, Sagittunio nasutus, and Utterbackiana implicata). Glochidia and juveniles of each species were exposed to a control and six concentrations of Instant Ocean® Sea Salt (IOSS), a synthetic sea salt that closely resembles the ionic composition of natural sea salt. Exposure concentrations were 1 part(s) per thousand (ppt), 2 ppt, 8.5 ppt, 12.5 ppt, 17 ppt, and 34 ppt. We calculated the median effect concentration (EC50) for each of the eight acute toxicity tests and found that glochidia were more sensitive than juveniles to IOSS. At hour 24 EC50s for the glochidia ranged from 0.38 to 3.6 ppt, with the most sensitive freshwater mussel being the nonsalinity-adapted A. ochracea, exhibiting an EC50 of 0.38 ppt (95% confidence interval [CI] 0.33–0.44). Juvenile freshwater mussels exhibited EC50s at hour 96 ranging from 5.0 to 10.4 ppt, with the least sensitive freshwater mussel being the nonsalinity-adapted A. ochracea, exhibiting an EC50 of 10.4 ppt (95% CI 9.1–12.0). Our results show that acute exposure to sea salt adversely affects freshwater mussel viability, particularly glochidia. This information can be used to enhance freshwater mussel conservation strategies in regions that are or will be impacted by climate-induced sea level rise and associated freshwater salinization. Environ Toxicol Chem 2023;00:1–12. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Enhancement of zinc (II) phthalocyanine photophysical properties in water by sulfonatocalix[4]arene‐based micelles

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Zinc phthalocyanines have demonstrated a wide range of applications as photosensitisers, particularly in organic synthesis, photocatalysis and photodynamic therapy. Although the introduction of ionic groups on the macrocycle periphery increases their water solubility, aggregation phenomena remain as a significant drawback for their application. In this study, amphiphilic sulfonatocalix[4]arene-based micelles were used to promote the monomerization of a cationic phthalocyanine through host–guest interactions. A comprehensive spectroscopic characterization was conducted, varying the concentration of sulfonatocalix[4]arene, and binding parameters were calculated to determine the optimal conditions for complete monomerization of the photosensitizer in water. Under these conditions, the combination of sulfonatocalix[4]arene and the photosensitizer activated its photophysical activity in aqueous media, showing significant singlet oxygen photoproduction, photocatalytic capability and photostability.

Ex‐Situ Generation of Bis(trifluoromethyl)disulfide and Applications to Trifluoromethylthiolation Reactions

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Herein, a convenient and operationally simple protocol for the ex-situ generation of bis(trifluoromethyl)disulfide from the readily available and commercial Langlois reagent is reported. The one-step synthesis of the toxic and volatile CF3SSCF3 is performed in a two-chamber reactor with simple PPh3 and N-bromosuccinimide as the activator, allowing for the safe handling and tandem utilization in direct trifluoromethylthiolation reactions. The versatility of the ex-situ generated CF3SSCF3 is demonstrated in known electrophilic, nucleophilic, and a radical trifluoromethylthiolation reactions. Furthermore, the application of the CF3SSCF3 in a copper-catalyzed cross-coupling with boronic acids is disclosed, showing good to excellent yields of trifluoromethyl-substituted aryl products, including pharmaceutically relevant molecules.

Trihydrogen Cation Helium Clusters: A New Potential Energy Surface

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Trihydrogen Cation Helium Clusters: A New Potential Energy Surface

A simple and new analytical potential energy surface (PES) for the interaction between the rigid trihydrogen cation and the helium atom is presented. This analytical PES is based on polarization and dispersion-repulsion forces. The parameters of this PES are fitted from data obtained from post Hartree-Fock calculations at the CCSD(T) level.


Abstract

We present a new analytical potential energy surface (PES) for the interaction between the trihydrogen cation and a He atom, , in its electronic ground state. The proposed PES has been built as a sum of two contributions: a polarization energy term due to the electric field generated by the molecular cation at the position of the polarizable He atom, and an exchange-repulsion and dispersion interactions represented by a sum of “atom-bond” potentials between the three bonds of and the He atom. All parameters of this new PES have been chosen and fitted from data obtained from high-level ab-initio calculations. Using this new PES plus the Aziz-Slaman potential for the interaction between Helium atoms and assuming pair-wise interactions, we carry out classical Basin-Hopping (BH) global optimization, semiclassical BH with Zero Point Energy corrections, and quantum Diffusion Monte Carlo simulations. We have found the minimum energy configurations of small He clusters doped with , , with N=1–16. The study of the energies of these clusters allows us to find a pronounced anomaly for N=12, in perfect agreement with previous experimental findings, which we relate to a greater relative stability of this aggregate.

Distinctive Arbutin‐Containing Markers: Chemotaxonomic Significance and Insights Into the Evolution of Proteaceae Phytochemistry

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Natural products isolation studies of eight endemic Tasmanian Proteaceae species – Agastachys odorata, Persoonia juniperina, Hakea megadenia, Hakea epiglottis, Orites diversifolius, Orites acicularis,Orites revolutus, and Telopea truncata – and three endemic Australian Proteaceae species Banksia serrata, Banksia praemorsa, and Banksia marginata were undertaken.Two previously unreported glycoside-derived natural products were identified, in addition to four other tremendously rare arbutin esters. The results of this study provide further evidence consistent with the proposal that these distinctive arbutin esters represent markers that can provide valuable insights into the chemical evolution of plant species within the family Proteaceae.

Carbon monoxide as a C1 building block in fine chemical synthesis

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Abstract

Carbon monoxide (CO) has become one of the most relevant and versatile renewable C1 building blocks for chemical synthesis, especially in the fine chemicals industry, due to the development of efficient and selective catalysts for its activation. In this review, we present a comprehensive critical analysis of the last 10 years literature on the use of CO as a renewable feedstock for fine chemicals production. The review is organized by type of catalytic reaction, namely alkene and alkyne carbonylation, hydroformylation, carbonylation of aryl halides, carbonylative cross-coupling and C–H carbonylation. Notable examples of the synthesis of relevant building blocks and/or known pharmaceuticals are highlighted. Emphasis is placed on examples of utilizing CO as the C1 building block in one or more catalytic steps. The catalyst used and the reaction conditions are consistently presented throughout all of the examples.

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A mini review of thin film composite membranes for organic solvent nanofiltration

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Organic solvent nanofiltration (OSN) is an emerging separation technology. Significant efforts have been dedicated to designing and fabricating thin film composite (TFC) membranes for OSN in recent years. The development and utilization of TFC membranes in OSN are paramount in ensuring the permeability of organic solvent and rejection of solute. Additionally, researchers have delved into optimizing preprocessing and post-treatment procedures during preparation. The preparation process has emerged as another avenue for improving the separation performance of TFC membranes. Simultaneously, various supports have been explored to enhance the TFC membranes' performance, including polymer substrates and inorganic substrates, as well as the interlayers between the substrate and the TFC membrane, each with unique advantages and disadvantages, and the choices of support depend on the specific requirements of the intended application. The limitations of conventional membranes could be overcome and thus achieve superior performance via an improved preparation strategy of the TFC membranes. This review presents a comprehensive overview of the preparation process for TFC membranes, including a detailed discussion of the preparation methods, the optimizing processes, and the substrates. Different TFC membranes for the OSN application is further discussed.