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Ab initio study of phosphine (PH 3) adsorption on the (001) palladium oxide (PdO) surface was performed with the GGA-PBE and vdW-DF2-C09 functionals, using the quantum ESPRESSO code. We found that PH 3 is very energetically stable on the bridge-ox (B 1) and top (T) sites of the PdO-O(001) and PdO-Pd(001) surfaces respectively with a coverage rate of 0.25 ML. The geometrical parameters of PH 3 in the free and adsorbed phase found are in agreement with the literature results. The study of the isosurfaces of the system constituted by PH 3 adsorbed on the B 1 and T sites of PdO-O(001) and PdO-Pd(001) respectively, leads on the one hand to a charge accumulation around the Phosphorus (P), oxygen (O) and palladium (Pd) atoms, and on the other hand to a loss of charge by the hydrogen atoms of PH 3. The study of the thermochemistry of PH 3 shows that it is favourable with the GGA-PBE functional, while it is unfavourable with the vdW-DF2-C09 functional. [Display omitted] • The adsorption and decomposition of PH 3 on PdO(001) surface have been investigated. • The adsorption of PH 3 on the PdO-O(001) surface with the GGA-PBE functional, is favourable at B 1 and H sites; while the PdO-Pd(001) surface, it is favourable on T and H sites. • For the vdW-DF2-C09 function, PH 3 adsorption on the PdO-O(001) surface is favourable at T and B 1 sites, while on the PdO-Pd(001) surface it is only favourable at T and B 3 sites. • The adsorption energies of PH 3 on both PdO-O(001) and PdO-Pd(001) surfaces is decreases as the coverage increase. • The thermochemical decomposition of PH 3 is favourable with the PdO-O(001) surface for the GGA-PBE functional. [ABSTRACT FROM AUTHOR]

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This systematic review aimed to analyze if using polywave light-emitting diodes (LED) to photoactivate resin-based materials (resin composites, adhesive systems, and resin cements) containing alternative photoinitiators provide better physicochemical properties than monowave ones. Inclusion criteria were in vitro studies that evaluated the degree of conversion, microhardness and flexural strength in resin-based materials containing alternative photoinitiators and light-activated with mono and polywave LEDs. Exclusion criteria were studies that evaluated the physicochemical properties of composites through any material interposed between the LED and the resin composite and studies that exclusively compared different modes and/or light activation times. Selection of studies, data extraction, and risk-of-bias analysis was performed. Data from selected studies were qualitatively analyzed. A systematic search was performed in June 2021 using PubMed/Medline, Embase, Scopus, and ISI Web of Science databases and grey literature without language restriction. A total of 18 studies were included in the qualitative analysis. Nine studies used diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) as an alternative photoinitiator for resin composite. Polywave LED improved the degree of conversion of resin composite compared to monowave in 9 of the included studies. Polywave LED improved the microhardness of resin composite compared to monowave in 7 of the included studies. Polywave LED improved the degree of conversion for 11 studies and microhardness of resin composite compared to monowave for 7 included studies. No differences in the flexural strength medium between poly and monowave LEDs were observed. The evidence was graded as low quality due to the high risk of bias for 11 studies. The existing studies, with their limitations, revealed that the polywave light-emitting diode maximizes activation, resulting in a higher degree of double-bond conversion and microhardness of resin composites containing alternative photoinitiators. However, the flexural strength of these materials is not influenced by the type of light activation device. • The replacement of camphorquinone with alternative photoinitiators is increasing in resin composites. • Alternative photoinitiators absorb light in different wavelengths compared to camphorquinone. • Polywave or dual-peak light emitting diodes (LEDs) have emerged as a solution to provide light in wavelengths within the violet spectrum that monowave LEDs are unable to provide. • The use of polywave LEDs seems to generate higher values of degree of conversion than monowave devices for resin composites containing alternative photoinitiators. [ABSTRACT FROM AUTHOR]

Among various strategies for CO 2 chemical fixation, the CO 2 cycloaddition with epoxides is one of the most promising and efficient approaches, in which ionic liquid (ILs) is a typical relatively environmentally friendly catalyst and medium. However, ILs decomposition and catalytic stability have not been in-depth investigated, and the structure-activity relationship of cations and anions has remained obscure, which would affect the understanding of catalytic behavior and catalyst loss, and limit the theoretical research and industrial application in CO 2 utilization. Therefore, based on a variety of phosphonium ILs we have designed and synthesized for CO 2 cycloaddition, the structure-activity relationship, steric hindrance and electronic effect of various anions and cations have been systematically studied in main and side reactions. Especially, a regulation strategy of cationic flexible steric hindrance and anionic electron effect have been developed to improve both ILs' activity and stability. Remarkably, the synergistic action of electron-donating effect, hydrogen bond and decreased acidity from flexible steric alkyl groups result in the spatial shielding of cation center and enhancement of the Br's leaving. Consequently, the quaternary phosphonium ILs with asymmetric flexible steric hindrance exhibit the optimal performance, showing propylene oxide (PO) conversion of 99.15% and propylene carbonate (PC) yield of 98.86%, which can efficiently decrease the formation of phosphine oxide, avoiding the decomposition of ILs. This discovery provides a new idea for developing stable and efficient CO 2 fixation system in sustainable industry. • Phosphine oxide generated from ILs' decomposition is first concerned and systematically investigated in CO 2 conversion. • Cationic steric hindrance and anionic electron effect are regulated to enhance both activity and stability. • Quaternary phosphonium ILs with asymmetric flexible groups exhibit excellent performance, avoiding phosphine oxide's formation. • Flexible alkyls' electron-donating effect and hydrogen-bond interaction lead to the spatial shielding and protection to cation center. • This discovery provides a novel avenue for developing CO 2 mitigation and fixation system in sustainable industry. [ABSTRACT FROM AUTHOR]

Abstract: A theoretical study of acidity and hydrogen bond acceptor properties of tetrahedric phosphine oxide derivatives have been carried out by means of MP2 computational methods. The results obtained for the mentioned complexes have been compared with the analogous ones of trimethylphosphine oxide. The strain decreases the complexation energy with metallic atoms as well as the thermodynamic and hydrogen bond acceptor (HBA) ability of the tetrahedric derivatives. [Copyright &y& Elsevier]

Abstract: The palladium(0) and palladium(II) catalysed Suzuki-Miyaura cross- coupling reaction has been established. We found that the optimized conditions are 1% PdCl2(PPh3)2, 1M aqueous Na2CO3 (2.5 eq.) and anthracene-phosphine oxide adduct (3) as a stable ligand (0.1 eq.) in only 4hours refluxing 1,4-dioxane. The reactions proceed in moderate to good yields with a diverse array of coupling partners as substrates. [Copyright &y& Elsevier]

Organophosphorus derivatives are widely used in human health care and have been detected in aquatic ecosystems. These compounds may pose significant risks to non-target exposed organisms and only limited studies are available on bioconcentration and the effects of organophosphorus derivatives on marine organisms. The aim of this work was to evaluate the possible toxic effects of two concentrations (20 and 40 μg/L) of γ-oximo- and γ-amino-phosphonates and phosphine oxides in mediterranean clams Ruditapes decussatus exposed for 14 days using different biomarkers and the changes of filtration and respiration rate. The use of clams in ecotoxicity evaluation is thus mandatory to assess the feasibility of assessing oxidative stress on R. decussatus after being exposed to γ-oximo- and γ-amino-phosphonates and phosphine oxides. The oxidative status was analyzed by measuring oxidative stress biomarkers RNS and ROS production in mitochondria, superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferases (GSTs), lipid peroxidation (LPO) and acetylcholinesterase (AChE), whose alteration was indicative of organophosphorus exposure, in both gills and digestive gland of the clams. No significant alterations in RNS, ROS production, SOD, CAT and AChE activities and MDA content were observed in both organs of clams treated with γ-oximophosphine oxides. It was possible then to hypothesize that γ-oximophosphine oxides may have probably exerted an incomplete alteration of antioxidant defenses and damage, which was changed by the activation of defense mechanisms. On the contrary, oxidative stress parameters were changed after exposure to γ-amino-phosphonates and phosphine oxides. In addition, metals accumulation, filtration and respiration rates were altered following exposure to all the studied organophosphorus compounds. [Display omitted] • Organophosphorus affect biochemical and physiological parameters on the clams. • Organophosphorus induced antioxidant response and chemical changes. • Neurotoxic effect could occur in contaminant dependent manner. [ABSTRACT FROM AUTHOR]