Search results for "Theoretical Chemistry"
showing 10 items of 8456 documents
The electronic structure of Ge9[Si(SiMe3)3]3-: a superantiatom complex.
2012
We report on the electronic structure of Ge(9)[Si(SiMe(3))(3)](3)(-). Systematic density functional theory analysis of the electronic shell structure of the cluster and its derivatives reveals that the Ge(9)[Si(SiMe(3))(3)](3)(-) and its neutral counterpart have electronic shells that can be explained using the superatom model. The ligand-core interaction of these complexes is distinctly different from previously identified gold, gallium, and aluminium superatom complexes, indicating an electron-donating rather than electron-withdrawing ligand. We modify the electron-counting rule for this case and introduce a simple picture for superatom and superantiatom complexes. Discussions comparing s…
Adsorption and Activation of Water on Cuboctahedral Rhodium and Platinum Nanoparticles
2017
Rh and Pt are widely used as the components in heterogeneous catalysts for multiple industrial applications. Because the metals are typically in the form of nanoparticles in real catalysts, it is important to carefully select models for the computational prediction of the catalytic properties. Here we report a first-principles study on the water activation, an important step in numerous catalytic reactions, using the finite-size Rh and Pt nanoparticle models and compare them to the extended surface models. We show that regardless of the model, adsorption and activation of water is practically identical for both metals, whereas the dissociation is energetically more favorable on Rh. The expe…
Understanding the White-Emitting CaMoO4 Co-Doped Eu3+, Tb3+, and Tm3+ Phosphor through Experiment and Computation
2019
In this article, the synthesis by means of the spray pyrolysis method, of the CaMoO4 and rare-earth cation (RE3+)-doped CaMoO4:xRE3+ (RE3+ = Eu3+, Tb3+, and Tm3+; and x = 1, 2, and 4% mol) compounds, is presented. The as-synthesized samples were characterized using X-ray diffraction, Rietveld refinement, field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, and photoluminescence (PL) spectroscopy. To complement and rationalize the experimental results, first-principles calculations, at the density functional theory level, have been performed to analyze the band structure and density of states. In addition, a theoretical method based on the calculations of surface energie…
Spin Crossover in Fe(II)–M(II) Cyanoheterobimetallic Frameworks (M = Ni, Pd, Pt) with 2-Substituted Pyrazines
2016
Discovery of spin-crossover (SCO) behavior in the family of Fe(II)-based Hofmann clathrates has led to a "new rush" in the field of bistable molecular materials. To date this class of SCO complexes is represented by several dozens of individual compounds, and areas of their potential application steadily increase. Starting from Fe(2+), square planar tetracyanometalates M(II)(CN)4(2-) (M(II) = Ni, Pd, Pt) and 2-substituted pyrazines Xpz (X = Cl, Me, I) as coligands we obtained a series of nine new Hofmann clathrate-like coordination frameworks. X-ray diffraction reveals that in these complexes Fe(II) ion has a pseudo-octahedral coordination environment supported by four μ4-tetracyanometallat…
A Particular Focus on the Prevalence of α- and β-Thalassemia in Western Sicilian Population from Trapani Province in the COVID-19 Era
2023
Thalassemia is a Mendelian inherited blood disease caused by α- and β-globin gene mutations, known as one of the major health problems of Mediterranean populations. Here, we examined the distribution of α- and β-globin gene defects in the Trapani province population. A total of 2,401 individuals from Trapani province were enrolled from January 2007 to December 2021, and routine methodologies were used for detecting the α- and β-globin genic variants. Appropriate analysis was also performed. Eight mutations in the α globin gene showed the highest frequency in the sample studied; three of these genetic variants represented the 94% of the total α-th…
On the Choice of the Extracellular Vesicles for Therapeutic Purposes
2019
Extracellular vesicles (EVs) are lipid membrane vesicles released by all human cells and are widely recognized to be involved in many cellular processes, both in physiological and pathological conditions. They are mediators of cell-cell communication, at both paracrine and systemic levels, and therefore they are active players in cell differentiation, tissue homeostasis, and organ remodeling. Due to their ability to serve as a cargo for proteins, lipids, and nucleic acids, which often reflects the cellular source, they should be considered the future of the natural nanodelivery of bio-compounds. To date, natural nanovesicles, such as exosomes, have been shown to represent a source of diseas…
A library of monoalkenylsilsesquioxanes as potential comonomers for synthesis of hybrid materials
2018
In this paper we demonstrate a facile and efficient synthesis of monoalkenylsubstituted POSS compounds, i.e., R7(Si8O12)-alkenyl and R7(Si8O12)(OSiMe2)-alkenyl with a functional alkenyl group of chain length (from vinyl to dec-9-enyl, with or without additional –OSiMe2– spacer between the silsesquioxane core and alkenyl moiety) and with five types of inert groups (Et, iBu, iOc, Cy, Ph) at the POSS core. These compounds constitute a library of monosubstituted POSS systems, including thorough spectroscopic and thermal characteristics. These findings could be especially useful for material chemists applying the compounds as modifiers or comonomers for copolymerization reaction, e.g., with olef…
Thiazole Analogues of the Marine Alkaloid Nortopsentin as Inhibitors of Bacterial Biofilm Formation
2020
Anti-virulence strategy is currently considered a promising approach to overcome the global threat of the antibiotic resistance. Among different bacterial virulence factors, the biofilm formation is recognized as one of the most relevant. Considering the high and growing percentage of multi-drug resistant infections that are biofilm-mediated, new therapeutic agents capable of counteracting the formation of biofilms are urgently required. In this scenario, a new series of 18 thiazole derivatives was efficiently synthesized and evaluated for its ability to inhibit biofilm formation against the Gram-positive bacterial reference strains Staphylococcus aureus ATCC 25923 and S. aureus ATCC 6538 a…
Protein tyrosine nitration and thiol oxidation by peroxynitrite-strategies to prevent these oxidative modifications.
2013
The reaction product of nitric oxide and superoxide, peroxynitrite, is a potent biological oxidant. The most important oxidative protein modifications described for peroxynitrite are cysteine-thiol oxidation and tyrosine nitration. We have previously demonstrated that intrinsic heme-thiolate (P450)-dependent enzymatic catalysis increases the nitration of tyrosine 430 in prostacyclin synthase and results in loss of activity which contributes to endothelial dysfunction. We here report the sensitive peroxynitrite-dependent nitration of an over-expressed and partially purified human prostacyclin synthase (3.3 μM) with an EC50 value of 5 μM. Microsomal thiols in these preparations effectively co…
Carbon Nitride-Based Catalysts for High Pressure CO2 Photoreduction
2022
In the current research, the productivity of CO2 photoreduction has been boosted by performing the reaction in an innovative photocatalytic reactor, which allows for operation up to 20 bar. A set of photocatalysts were used, including three types of pristine TiO2, i.e., one commercially prepared (Evonik P25), one home-prepared by flame spray pyrolysis (FSP), and one obtained by the hydrolysis of TiCl4 (TiO2exCl), a bare thermo-exfoliated carbon nitride (C3N4-TE), and binary materials composed of TiO2 and C3N4-TE. The photoreduction was carried out in water at pH 14 and in the presence of Na2SO3 as a hole scavenger. Hydrogen and very small amounts of CO were detected in the head space of the…