Tracing electron density changes in langbeinite under pressure

Pressure is well known to dramatically alter physical properties and chemical behaviour of materials, much of which is due to the changes in chemical bonding that accompany compression. Though it is relatively easy to comprehend this correlation in the discontinuous compression regime, where phase transformations take place, understanding of the more subtle continuous compression effects is a far greater challenge, requiring insight into the finest details of electron density redistribution. In this study, a detailed examination of quantitative electron density redistribution in the mineral langbeinite was conducted at high pressure. Langbeinite is a potassium magnesium sulfate mineral with the chemical formula [K2Mg2(SO4)3], and crystallizes in the isometric tetartoidal (cubic) system. The mineral is an ore of potassium, occurs in marine evaporite deposits in association with carnallite, halite and sylvite, and gives its name to the langbeinites, a family of substances with the same cubic structure, a tetrahedral anion, and large and small cations. Single-crystal X-ray diffraction data for langbeinite have been collected at ambient pressure and at 1 GPa using a combination of in-house and synchrotron techniques. Experiments were complemented by theoretical calculations within the pressure range up to 40 GPa. On the basis of changes in structural and thermal parameters, all ions in the langbeinite structure can be grouped into `soft' (potassium cations and oxygens) and `hard' (sulfur and magnesium). This analysis emphasizes the importance of atomic basins as a convenient tool to analyse the redistribution of electron density under external stimuli such as pressure or temperature. Gradual reduction of completeness of experimental data accompanying compression did not significantly reduce the quality of structural, electronic and thermal parameters obtained in experimental quantitative charge density analysis.

Formulating The Structural Aspects Of Various Benzimidazole Cognates

Background: Benzimidazole derivatives are widely used in clinical practice as potential beneficial specialists. Recently, the neuroprotective effect of derivatives of benzimidazole moiety has also shown positive outcomes. Objective: To develop favourable molecules for various neurodegenerative disorders using the versatile chemical behaviour of the benzimidazole scaffold. Methods: About 25 articles were collected that discussed various benzimidazole derivatives and categorized them under various subheadings based on the targets such as BACE 1, JNK, MAO, choline esterase enzyme, oxidative stress, mitochondrial dysfunction in which they act. The structural aspects of various benzimidazole derivatives were also studied. Conclusion: To manage various neurodegenerative disorders, a multitargeted approach will be the most hopeful stratagem. Some benzimidazole derivatives can be considered for future studies, which are mentioned in the discussed articles.

Characterisation of the chemo-mechanical behaviour of clays polluted by BTEX: a case study of benzene

In chemo-mechanical coupling of clays, chemical phenomena are likely to have a stronger influence on the mechanical behaviour and mechanical actions can modify the chemical behaviour. The understanding of these different phenomena, taking into account the coupled mechanisms, is essential in the context of the problem of the durability of structures and works built on polluted sites. Thus, the laboratory characterisation of the chemo-mechanical behaviour of a clay contaminated by light hydrocarbon pollutant (BTEX: benzene) was carried out. First in the absence of pollutants, i.e., by the presence of water only, then under the influence of the pollutant, all in two stages: with no external stress, then under imposed external stress. This study presents an experimental protocol based on a series of uniaxial consolidation tests, specific oedometric tests and direct shear strength, this tests performed under controlled saturation conditions and in the presence of organic contamination by benzene. All results confirm the influence of pollutants in different concentrations on the mechanical behaviour of the soil. They show a strong increase in compressibility and a significant increase in swelling, the soil becomes more cohesive, low friction and less elastic. Furthermore, the results show that external load forces play a major role in modifying the behaviour of clay.

Synthesis, Characterization and Theoretical Insights into Molecular Properties of 2-(4-fluorophenyl)-4H-chromen-4-one

Flavone scaffold is one of the most often perceived parts in biologically active organic compounds. In light of this, a flavone; 2-(4-fluorophenyl)-4H-chromen-4-one (FPC) has been synthesized, characterized and studied by using density functional theory (DFT) at B3LYP/6-31G(d,p) basis set. The geometry of the FPC molecules has been optimized by using B3LYP/6-31G(d,p) basis set and in-depth structural analysis on bond lengths and bond angles has been discussed. The HOMO-LUMO analysis and various quantum chemical parameters are computed and discussed for the better understanding of chemical behaviour of the title molecule. Molecular electrostatic potential (MEP) surface investigation is presented to understand the reactivity sites of the title molecule.