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.

Cyclization of 2,4‐dinitronaphth‐1‐yl amino acids and their analogues to naphthimindazol‐N‐oxides: Kinetics and mechanism

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Cyclization of 2,4-dinitronaphth-1-yl amino acids and their analogues to naphthimindazol-N-oxides: Kinetics and mechanism

Reaction of 1-chloro-2,4-dinitronaphthalene with amino acids and their methyl esters.


Abstract

A variety of novel naphthimindazol-N-oxides and naphththiazol-N-oxide have been prepared in a simple two-step process. The first step involves the reaction of 1-chloro-2,4-dinitronaphthalene with glycine, alanine, glycolic acid, thioglycolic acid, and their methyl esters affording substitution products, the subsequent treatment of which with base furnishes naphthimindazol-N-oxide and naphththiazol-N-oxide derivatives. Stepwise reaction mechanisms via carbanions, nitrogen anions, and spiro Meisenheimer intermediates are proposed. The action of 10% NaOH in dioxane on the substitution products was measured spectrophotochemically, and the kinetic studies suggested that the N-naphthyl glycine and N-naphthyl alanine follow a second-order rate law while S-naphthyl thioglycolic acid is accurately first-order kinetics.

Molecular Conformations of Shape Anisometrically Variant Mesogens in Liquid Crystalline Phase Studied by 13C NMR Spectroscopy

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Mesogens that vary in shape anisometry have been investigated by 13C solid-state NMR in the liquid crystalline phase to inspect the conformations. The molecules examined comprise of (i) rod-like mesogen with three-phenyl ring core and terminal hexyloxy chains, (ii) three-ring core linked to the fourth phenyl ring via a spacer, and (iii) trimesic acid connected to three side arms core units through a spacer. The order parameter (Szz) values for the phenyl rings of the rod-like mesogen are 0.65-0.68, while the mesogen with a three-ring core linked to a phenyl ring via spacer showed dissimilarity. Consequently, for the core unit's phenyl rings, Szz is ~ 0.70, and the terminal phenyl ring showed a low value of 0.12. For the trimesic acid based mesogen, the Szz value for the side arm phenyl rings is ~ 0.53, and for the central phenyl ring, a very low value of 0.11 is witnessed. By considering the ordering of the rod-like mesogen as a yardstick and employing the ratios of Szz values of the phenyl rings, the average conformations of other mesogens are arrived. Accordingly, for the trimesic acid based mesogen, a tripod-like conformation instead of l shape is proposed in the liquid crystalline phase.

Fabrication of a Novel Co/CoO@Fe2V4O13 Composite Catalyst as a Photoanode for Enhanced Photoelectrochemical Water Oxidation

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Fabrication of a Novel Co/CoO@Fe2V4O13 Composite Catalyst as a Photoanode for Enhanced Photoelectrochemical Water Oxidation

Schematic showing the probable charge transfer mechanism in a p-n junction consisting of p-type CoO and n-type Fe2V4O13. The depletion region is formed at the interface due to the diffusion of charge


Abstract

Herein, the synthesis of a novel composite photocatalyst, Co/CoO@Fe2V4O13, is reported by the deposition of CoO metal oxide nanoparticles on the surface of Fe2V4O13 bimetallic oxide. The synthesised photocatalyst exhibited a band gap of roughly 1.8 eV, rendering it responsive to the complete visible light spectrum of the sun, thereby enabling optimal absorption of solar radiation. The Co/CoO@Fe2V4O13 composites demonstrated an enhanced photoelectrochemical water oxidation capacity compared to pristine Fe2V4O13 when exposed to visible light. The enhanced performance is attributed primarily to the creation of a p-n junction at the interface of Fe2V4O13 and Co/CoO, as well as the Z-scheme charge transfer mechanism, which aids in the separation and transfer of photogenerated charge carriers. Light absorption by Co nanoparticles via plasmonic excitation and intra- and inter-band transitions in the composite structure is also likely, resulting in increased composite efficiency. Our findings indicate that Co/CoO@Fe2V4O13 composites show promising performance for solar water splitting applications and offer new perspectives for designing effective photocatalysts.

Targeting Ultrafast Spectroscopic Insights into Red Fluorescent Proteins

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Targeting Ultrafast Spectroscopic Insights into Red Fluorescent Proteins

Red fluorescent proteins (RFPs) have powered bioimaging advances in life sciences due to their long-wavelength emissions and reduced phototoxicity. Recent advances in engineering, characterizing, and optimizing several major categories of RFPs have included photoconvertible, photoswitchable, large Stokes shift, and noncanonical FPs that achieve red emissions. A critical correlation of the available crystallographic and spectroscopic results can provide ultrafast and functional structural dynamics insights into the redding mechanisms of RFPs, which range from characteristic ring twists, conjugation extension to excited state proton transfer. More information can be found in the Review by Taylor Krueger, Cheng Chen, and Chong Fang.


Fuel Property Enhancement of Jatropha Biodiesel by Blending with Nanoparticles

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Fuel Property Enhancement of Jatropha Biodiesel by Blending with Nanoparticles

Nanoparticles are utilized as additives to enhance the fuel properties of biodiesel. The application of Mg-ZnO as a promising fuel property enhancer is highlighted and the protocol for its synthesis is provided. The fuel property enhancement of biodiesel in terms of fuel density, oxidation stability, and dynamic viscosity by Mg-ZnO is compared with other nanoparticles such as ZnO, SiO2, and TiO2.


Abstract

The direct application of Jatropha biodiesel in engines is harmful because of the corrosivity of biodiesel, the emission of poisonous gases, and solid particulate matter. Therefore, it is of paramount important to enhance the biodiesel fuel properties via green routes to effectively utilize it for automotive applications. The synthesis and application of different nanoparticles (NPs) such as ZnO, Mg-ZnO, TiO2, and SiO2, as fuel property enhancers for Jatropha biodiesel were investigated. The calorific value, oxidation stability, dynamic viscosity etc. were studied for the NP-blended biodiesels and compared with the traditional biodiesel (B100). Mg-ZnO was found to be a promising candidate as fuel property enhancer for biodiesels.

Monitoring Conformation and Protonation States of Glutathione by Raman Optical Activity and Molecular Dynamics

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Monitoring Conformation and Protonation States of Glutathione by Raman Optical Activity and Molecular Dynamics

The cover feature image shows measurement of Raman optical activity spectra, which provide extended information about molecular behavior in solutions. If coupled with multi-scale density functional theory and molecular dynamics computations, whole potential energy maps can be deduced from the spectra. The maps can serve, for example, to verify or improve common force fields. For glutathione, a limited effect of pH on the backbone conformation was found. More information can be found in the Research Article by Petr Bouř and co-workers.