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Engineered nanoparticles (NPs) are being studied for their potential to harm humans and the environment. Biological activity, toxicity, physicochemical properties, fate, and transport of NPs must all be evaluated and/or predicted. In this work, we explored the influence of metal oxide nanoparticle facets on their toxicity towards bronchial epithelial (BEAS-2B), Murine myeloid (RAW 264.7), and E. coli cell lines. To estimate the toxicity of metal oxide nanoparticles grown to a low facet index, a quantitative structure–activity relationship ((Q)SAR) approach was used. The novel model employs theoretical (density functional theory calculations) and experimental studies (transmission electron microscopy images from which several particle descriptors are extracted and toxicity data extracted from the literature) to investigate the properties of faceted metal oxides, which are then utilized to construct a toxicity model. The classification mode of the k-nearest neighbour algorithm (EnaloskNN, Enalos Chem/Nanoinformatics) was used to create the presented model for metal oxide cytotoxicity. Four descriptors were identified as significant: core size, chemical potential, enthalpy of formation, and electronegativity count of metal oxides. The relationship between these descriptors and metal oxide facets is discussed to provide insights into the relative toxicities of the nanoparticle. The model and the underpinning dataset are freely available on the NanoSolveIT project cloud platform and the NanoPharos database, respectively. [ABSTRACT FROM AUTHOR]

A density functional theory study was performed on the [3+2] cycloaddition (32CA) reaction of 1 H -phosphorinium-3-olate and 1-methylphosphorinium-3-olate with methyl acrylate. The thermodynamic and kinetic parameters were analysed by considering the regio- and stereoisomeric pathways in gas phase and solvents. The geometries indicate that the transition states are slightly more advanced and asynchronous in ethanol. Electron localisation function topological analysis of the bonding changes along the most favourable reaction pathway associated with the 32CA reaction of 1 H -phosphorinium-3-olate with methyl acrylate indicates that the reaction takes place through a two-stage one-step mechanism. Non-covalent interactions analysis of TS6x-H reveals the existence of weak hydrogen bonding explaining the regioselectivity found in this low-polar zw-type 32CA reaction. On comparing these theoretical findings with the nitrogen analogues of the 32CA reactions, it is found that the regioselectivity is affected and the pathways are kinetically and thermodynamically enhanced. Therefore, a priori , the phosphorus cycloadducts could be synthesised. [ABSTRACT FROM AUTHOR]

Highlights: [•] The 1,3-dipolar cycloaddition of pyrazinium-3-olates are studied theoretically. [•] The level of theory used is B3LYP/6-31G(d). [•] Parr functions were used to have a better understanding of the reaction mechanism. [•] The findings will be helpful for future synthesis of the reported compounds. [Copyright &y& Elsevier]

Abstract: The excited-state intramolecular proton transfer (ESIPT) fluorescence of the synthesised 2-(1,3-benzothiazol-2-yl)-5-(N,N- diethylamino)phenol (1) was studied using spectroscopic and theoretical methods. The changes in the electronic transition, energy levels, and orbital diagrams were investigated using the ab initio molecular orbital computation [B3LYP/6-31G(d)]. Compound (1) is fluorescent; it shows a single absorption and dual emission in solvents of different polarities. Experimental absorption and emission wavelengths are in good agreement with those predicted using the Time-Dependent Density Functional Theory [TD-B3LYP/6-31G(d)]. The photophysical properties of compound (1) are compared with benzoxazole and benzimidazole analogues. [Copyright &y& Elsevier]

Theoretical studies were performed on seven potential interstellar and circumstellar substituted cyanoacetylenes, Y(C C)CN [Y = C 2 H 5 , C 3 H 7 , C 4 H 9 , F, Cl, Br and CN]. Geometry optimizations were carried out using the DFT/B3LYP, the CCSD and CCSD(T) levels of theory. The cc-pVTZ basis set was used for all atoms. Frequency computations were also carried out at the same level of theory as for the optimization to check the nature of the stationary points. The molecular and spectroscopic parameters of the cyanoacetylenes were computed. An analysis of these parameters is in line with the satisfactory performance of the B3LYP/cc-pVTZ level compared to the golden standard, the CCSD(T) level. The theoretical data reported in this work should facilitate future identifications of these cyanoacetylenes in extraterrestrial locations. Plausible mechanisms for the formation of these molecules have been proposed. [ABSTRACT FROM AUTHOR]

The reaction of the rhenium(V) complex cis-[ReO2I(PPh3)2] with 2-aminothiophenol (H2atp), benzene-1,2-dithiol (H2tdt) and 2-hydroxybenzenethiol (H2otp) led to the formation of the rhenium(III) complexes [Re(Hatp)(ibsq)2]·OPPh3, [Re(sbsq)3]·OPPh3 and [Re(obsq)3]·OPPh3 (ibsq=2-iminothiobenzosemiquinonate, sbsq=1,2-dithiobenzosemiquinonate, obsq=2-hydroxothiobenzosemiquinonate) respectively. These paramagnetic complexes were characterized by single crystal X-ray crystallography, 1H NMR spectrometry, IR and electronic spectroscopy, and cyclic voltammetry. To complement the experimental data, density functional theory (DFT) and time-dependent DFT were successfully used to investigate the structural, molecular, infrared and electronic spectra of these three complexes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Chalcogen surface additives boost the catalytic activity of Pt (1 1 1) surfaces. • S and Se surface additives are better catalytic activity boosters. • Dehydrogenation proceeds with or without indoline as an intermediate. • All the adsorbates stably adsorb on the surfaces with additives. Liquid organic hydrogen carrier (LOHC) systems have gained serious traction of late due to their potential application in the envisaged hydrogen economy. This is mainly because LOHCs can undergo reversible dehydrogenation in the presence of a catalyst. Using density functional theory calculations with van der Waals corrections, the role of chalcogens (S, Se and Te) as surface additives, in boosting the catalytic activity of Pt (1 1 1) surface, was investigated for the dehydrogenation of the LOHC system, octahydroindole to indole. The calculated adsorption energies indicate that octahydroindole (the hydrogen rich form (LOHC+)) and indole (the hydrogen lean form (LOHC−)) stably adsorbs on the Pt (1 1 1) surface(s) in the presence of chalcogen surface additives. The S and Se atoms were found to be better catalytic activity boosters in lowering the calculated reaction energy for dehydrogenating octahydroindole to indole than the Te atom. For all the considered chalcogen surface additive species, the calculated reaction energies indicate that the dehydrogenation of octahydroindole to indole can proceed either with or without indoline as a reaction intermediate. [ABSTRACT FROM AUTHOR]