Energetic and Geometric Characteristics of Substituents, Part 3: The Case of NO2 and NH2 Groups in Their Mono-Substituted Derivatives of Six-Membered Heterocycles

Substituted heterocyclic arenes play important roles in biochemistry, catalysis, and in the design of functional materials. Exemplary six-membered heteroaromatic molecules, that differ from benzene by inclusion of one heteroatom, are pyridine, phosphorine, arsabenzene, and borabenzene. This theoretical study concerns the influence of the heteroatom present in these molecules on the properties of substituents of two types: electron-donating (ED) NH2 group and electron-accepting (EA) NO2 group, attached at the 2-, 3-, or 4-position. The effect is evaluated by the energy of interaction (Erel) between the substituent and the substituted system and electronic properties of the substituents described by the charge of the substituent active region (cSAR) index. In addition, several geometric descriptors of the substituent and heteroaromatic ring, as well as changes in the aromaticity, are considered. The latter are assessed using the Electron Density of Delocalized Bonds (EDDBs) property of delocalized π electrons. The obtained results show that the electronegativity (EN) of the heteroatom has a profound effect on the EA/ED properties of the substituents. This effect is also reflected in the geometry of studied molecules. The Erel parameter indicates that the relative stability of the molecules is highly related to the electronic interactions between the substituent and the heteroarene. This especially applies to the enhancement or weakening of π-resonance due to the EN of the heteroatom. Additionally, in the 2-heteroarene derivatives, specific through-space ortho interactions contribute to the heteroatom effects.

Conditions for electronic hybridization between transition-metal dichalcogenide monolayers and physisorbed carbon-conjugated molecules

Hybridization effects play a crucial role in determining the electronic properties of hybrid inorganic/organic interfaces. To gain insight into these important interactions, we perform a first-principles study based on hybrid density-functional theory including spin-orbit coupling, focusing on eight representative systems formed by two carbon-conjugated molecules-pyrene and perylene-physisorbed on the transition-metal dichalcogenide monolayers (TMDCs) MoS2, MoSe2 WS2, and WSe2. By means of band unfolding techniques, we analyze the band structures of the considered materials, identifying the contributions of the individual constituents as well as the signatures of their hybridization. Based on symmetry and energetic arguments, we derive general conditions for electronic hybridization between conjugated molecules and underlying TMDCs even when the former do not lie planar on the latter, thus providing the key to predict how their mutual arrangement affect their electronic interactions.

Cell Penetrating Peptide-Based Self-Assembly for PD-L1 Targeted Tumor Regression

Cell penetrating peptides (CPPs) are peptides that can directly adapt to cell membranes and then permeate into cells. CPPs are usually covalently linked to the surface of nanocarriers to endow their permeability to the whole system. However, hybrids with lipids or polymers make the metabolism much more sophisticated and even more difficult to determine. In this study, we present a continuous sequence of 18 amino acids (FFAARTMIWY(d-P)GAWYKRI). It forms nanospheres around 170 nm, which increase slightly after loading with siRNA and DOX. Notably, it can be internalized by cancer cells mainly through electronic interactions and PD-L1-mediated endocytosis. Compared with poly-l-lysine and polyethyleneimine, it has a much higher efficiency (about four times) of gene transduction while lowering toxicity. In the treatment of cancer, it causes apoptosis (21%) and inhibits the expression of SURVIVIN protein in vitro. In vivo, it shows good biocompatibility as there are no changes in mice’s body weight. When administering peptide-siRNA-DOX, tumor growth is inhibited the most (about three times). These results above prove the sequence to be a good candidate for gene therapy and drug delivery.

Strategies to Mitigate Chemotherapy and Radiation Toxicities That Affect Eating

Background: Cancer and its therapy is commonly associated with a variety of side effects that impact eating behaviors that reduce nutritional intake. This review will outline potential causes of chemotherapy and radiation damage as well as approaches for the amelioration of the side effects of cancer during therapy. Methods: Information for clinicians, patients, and their caregivers about toxicity mitigation including nausea reduction, damage to epithelial structures such as skin and mucosa, organ toxicity, and education is reviewed. Results: How to anticipate, reduce, and prevent some toxicities encountered during chemotherapy and radiation is detailed with the goal to improve eating behaviors. Strategies for health care professionals, caregivers, and patients to consider include (a) the reduction in nausea and vomiting, (b) decreasing damage to the mucosa, (c) avoiding a catabolic state and muscle wasting (sarcopenia), and (d) developing therapeutic alliances with patients, caregivers, and oncologists. Conclusions: Although the reduction of side effects involves anticipatory guidance and proactive team effort (e.g., forward observation, electronic interactions, patient reported outcomes), toxicity reduction can be satisfying for not only the patient, but everyone involved in cancer care.

The Importance of Molybdenum(IV) Active Sites in Promoting Electrochemical Reduction of N2 to NH3 with MoFe Bimetallic Catalysts

To overcome the low faradaic efficiency (FE) of single Mo or Fe based electrocatalysts in nitrogen reduction reactions (NRR) due to the competition from the hydrogen evolution reaction (HER), a series of bimetallic MoFe compound catalysts were prepared under an NH3 atmosphere through a facile precipitation-pyrolysis method. The formed tetravalent Mo was found to be capable of inducing better electronic interactions between the surface nitrogen species and the Fe metal groups, thus improving the FE. It was demonstrated that the prepared ternary MoFe-N catalyst exhibited a remarkable FE of 33.26 % and a high NH3 yield of 33.31 μg h-1 mg-1cat. for NRR, which was believed to have been caused by an obvious change in the valence of Mo that resulted in a lower HER activity. X-ray photoelectron spectroscopy analysis further revealed that thermal processing under an NH3 atmosphere formed the Mo(IV) active sites in Mo-N bond, which led to a significant suppression in HER activity. Finally, through the study of the surface hydrogenation mechanism, it was concluded that the synergistic effect of the adsorbed H* and Mo active sites was the main reason for the improved performance of NRR.

Synthesis of ultrathin rhenium disulfide nanoribbons using nano test tubes

The synthesis of ultrathin rhenium disulfide (ReS2) nanoribbons within single-walled carbon nanotubes (SWNTs) has been established. Dirhenium decacarbonyl complex is encapsulated into the SWNTs to provide a source of confined rhenium atoms, which readily react with iodine to form discrete nm-sized clusters of rhenium iodide [Re6I14]2− embedded in the nanotubes. The final step of the synthesis is accomplished by admitting hydrogen sulfide gas into nano test tubes, yielding twisted nanoribbons of rhenium disulfide encapsulated in carbon nanotubes, ReS2@SWNTs. The width, structure, and composition of rhenium disulfide nanoribbons are strictly controlled by the extreme confinement of the host-SWNT. A holistic analytical approach combining complementary imaging and analysis methods is used at each synthetic step to elucidate the structure and composition of the guest material and reveal the role of the SWNT contributing towards the electronic interactions with encapsulated inorganic structures. As ReS2 nanoribbons are expected to retain the electronic properties of the bulk material, such as direct bandgap, the low dimensional form of this material can be of interest for use in nanoscale electronic devices.