Theoretical Investigation on Dialumenes toward Dihydrogen Activation: Mechanism and Ligand Effect.

Herein, we report a computation study based on the density functional theory calculations to understand the mechanism and ligand effect of the base-stabilized dialumenes toward dihydrogen activation. Among all of the examined modes of dihydrogen activation using the base-stabilized dialumene, we found that the concerted 1,2-hydrogenation of the Al═Al double bond is kinetically more preferable. The concerted 1,2-hydrogenation of the Al═Al double bond adopts an electron-transfer model with certain asynchrony. That is, the initial electron donation from the H-H σ bonding orbital to the empty 3p orbital of the Al1 center is followed by the backdonation from the lone pair electron of the Al2 center to the H-H σ antibonding orbital. Combined with the energy decomposition analysis on the transition states of the concerted 1,2-hydrogenation of the Al═Al double bond and the topographic steric mapping analysis on the free dialumenes, we ascribe the higher reactivity of the aryl-substituted dialumene over the silyl-substituted analogue in dihydrogen activation to the stronger electron-withdrawing effect of the aryl group, which not only increases the flexibility of the Al═Al double bond but also enhances the Lewis acidity of the Al═Al core. Consequently, the aryl-substituted dialumene fragment suffers less geometric deformation, and the orbital interactions between the dialumene and dihydrogen moieties are more attractive during the 1,2-hydrogenation process. Moreover, our calculations also predict that the Al═Al double bond has a good tolerance with the stronger electron-withdrawing group (-CF3) and the weaker σ-donating N-heterocyclic carbene (NHC) analogue (e.g., triazol carbene and NHSi). The reactivity of the dialumene in dihydrogen activation can be further improved by introducing these groups as the supporting ligand and the stabilizing base on the Al═Al core, respectively.

Construction of N-doped carbon encapsulated CoP hollow nanofibers as multifunctional electrode materials for potassium-ion and lithium-sulfur batteries.

Herein, a composite of N-doped carbon coated phosphating cobalt hollow nanofibers (N/C@CoP-HNFs) was synthesized by electrospinning, phosphating, and carbon coating processes. When employed as multifunctional electrode materials for potassium-ion batteries (PIBs) and lithium-sulfur (Li-S) batteries, the N/C@CoP-HNFs demonstrated notable electrochemical properties. Specifically, it delivered an initial specific capacity of 420.4 mA h g-1 at a current density of 100 mA g-1, with a sustained capacity of 190.8 mA h g-1 after 200 cycles in PIBs, and a specific capacity of 1448 mA h g-1 at a current density of 0.5C in Li-S batteries, which is considered relatively high for these types of battery technology. This good performance may due to the combination of the carbon nitrogen layer and cobalt phosphide bilayer hollow tube structure, which is conducive to telescoping the diffusion length of ions and electrons and buffer volume variation, and effectively inhibits the shuttle effect. Density functional theory (DFT) calculations were also used to explore the energy storage mechanism of the material. The possible adsorption sites and corresponding adsorption energy of K+ were analyzed, and the advantages of the material were explored by calculating the diffusion barrier and state density. The theoretical simulations further validated the strong adsorption capability of CoP for polysulfides. This work is expected to provide new ideas for new energy storage materials.

Oxalamide ligands with additional coordinating groups for Cu-catalyzed arylation of alcohols and phenols.

A novel class of chain-like multidentate oxalamide ligands with additional coordinating groups was developed for the coupling of (hetero)aryl bromides with both alcohols and phenols under mild conditions. Introduction of oxygen atoms in N-alkyl chains is pivotal for the high catalytic efficiency and broad substrate versatility.

Metal-free ß,γ-C(sp3)-H difunctionalization of propanols: DMP-initiated asymmetric spirocyclopropanation.

A DMP-initiated metal-free effective ß,γ-asymmetric spirocyclopropanation of propanols strategy using oxidative iminium activation is described. This process has been realized by a synergistic amine-catalyzed one-pot cascade oxidation-Michael addition cyclopropanation for "one-pot" access to various spirocyclopropyl propionaldehydes/propanols from diverse 3-arylpropanols and α-brominated active methylene compounds under mild conditions and with high enantioselectivity (ee up to >99%).

The comprehensive detection of miRNA, lncRNA, and circRNA in regulation of mouse melanocyte and skin development

BACKGROUND: Pigmentation development, is a complex process regulated by many transcription factors during development. With the development of the RNA sequencing (RNA-seq), non-coding RNAs, such as miRNAs, lncRNAs, and circRNAs, are found to play an important role in the function detection of related regulation factors. In this study, we provided the expression profiles and development of ncRNAs related to melanocyte and skin development in mice with black coat color skin and mice with white coat color skin during embryonic day 15 (E15) and postnatal day 7 (P7). The expression profiles of different ncRNAs were detected via RNA-seq and also confirmed by the quantitative real-time PCR (qRT-PCR) method. GO and KEGG used to analyze the function the related target genes. RESULTS: We identified an extensive catalogue of 206 and 183 differently expressed miRNAs, 600 and 800 differently expressed lncRNAs, and 50 and 54 differently expressed circRNAs, respectively. GO terms and pathway analysis showed the target genes of differentially expressed miRNA and lncRNA. The host genes of circRNA were mainly enriched in cellular process, single organism process. The target genes of miRNAs were mainly enriched in chromatin binding and calcium ion binding in the nucleus. The function of genes related to lncRNAs are post translation modification. The competing endogenous RNA (ceRNA) network of lncRNAs and circRNAs displays a complex interaction between ncRNA and mRNA related to skin development, such as Tcf4 , Gnas , and Gpnms related to melanocyte development. CONCLUSIONS: The ceRNA network of lncRNA and circRNA displays a complex interaction between ncRNA and mRNA related to skin development and melanocyte development. The embryonic and postnatal development of skin provide a reference for further studies on the development mechanisms of ncRNA during pigmentation.