Spectroscopy, NMR and DFT studies on molecular recognition of crown ether bridged chiral heterotrinuclear salen Zn(II) complex

A barium-containing crown ether bridged chiral heterotrinuclear salen Zn(II) complex BaZn2L(ClO4)2, where L is a folded dinuclear chiral (R,R)-salen ligand, has been synthesized and characterized by elemental analysis, 1H NMR, UV-vis, IR, circular dichroism (CD) spectra, and mass spectra. As a folded dinuclear chiral host, its recognition with achiral guests (imidazole derivatives), rigid bidentate guest (1,4-diazobicyclo[2,2,2]octane, DABCO) and chiral guests (amino acid methyl esters) was investigated by means of UV-vis spectrophotometric titration, CD spectra. The association constants of D-amino acid methyl esters are found to be higher than those of their L-enantiomer. The sandwich-type binding of BaZn2L(ClO4)2-DABCO supramolecular assembly was specially studied via 1H NMR titration and 1H ROESY. To understand the recognition on molecular level, density functional theory (DFT) calculations on B3LYP/LanL2DZ were performed on the minimal energy conformations of host, guests, and host-guest complexes. The minimal energy conformations were obtained by molecular mechanics (MM) optimization and molecular dynamics (MD) simulation. The results of single point energy, HOMO energy, and charges transfer were analyzed. The results of theoretical calculations are in good agreement with the experimental data.     

Radical-induced formation of some siloles and diazasiloles

The Bu(3)Sn radical-induced reaction of o-iodobenzylvinylsilanes and o-iodoallylsilanes leads to cyclic products in yields of 40-60%. These regioselective cyclizations occur with high preference for a 5-exo and a 7-endo mode with a 6-exo mode being absent. An example for ring closure via a 7-exo mode is described.     

Hybridized local and charge-transfer excited state fluorophores enabling organic light-emitting diodes with record high efficiencies close to 20%

Pure organic emitters with full utilization of triplet excitons are in high demand for organic light-emitting diodes (OLEDs). Herein, through modulation of electron donors and introduction of phenyl rings as π spacers, we present three pure organic fluorophores (BCz, BTCz and BPTCz) with the hybridized local and charge-transfer (HLCT) excited state feature for OLED fabrication. Importantly, the introduction of π spacers in BPTCz not only enhances locally excited character with a fast radiative decay but also promotes intermolecular interactions to suppress non-radiative decays, contributing to a high solid-state fluorescence efficiency over 90%. Significantly, BPTCz not only endows its doped OLEDs with an external quantum efficiency (EQE) up to 19.5%, but also its non-doped OLED with a high EQE of 17.8%, and these outstanding efficiencies are the state-of-the-art performances of HLCT-based OLEDs.

Three purely organic fluorophores with a hybridized local and charge-transfer excited state feature are presented and enabled organic light-emitting diodes with record high external quantum efficiencies close to 20%.     

配合物[Co(2，3-tri)2Cl]·ZnCl4·Cl·H2O和[Co(amp)3]·amph·Cl·2ZnCl4·H2O合成及晶体结构

采用三元胺及二元胺混配方法进行[Co(N)₅Cl]²⁺配合物的合成，分离出分别由三元胺配体和二胺配体构成的2个钴胺配合物。晶体结构测定表明由三元胺配体构成的钴胺配合物中，三元胺为N-(2-Aminoethyl)-1，3-propanediamine(记为2，3-tri)，但并未以六胺形式配位[Co(N)₆]³⁺，而以六胺五配位形式形成[Co(N)₆Cl]²⁺，这     

Synthesis and electrochemical properties of 2,6-bis（6-aryl-[1,2,4]- triazolo[3,4-b][1,3,4]-thiadiazole-3-yl）pyridines

By the condensation of 2,6-bis（4-amino-5-mercapto-[1,2,4]-triazoles-2）pyridine with aromatic acid in the presence of phosphorus oxychloride. Compounds of 2,6-bis（6-aryl-[1,2,4]-triazolo[3,4-b][1,3,4]-thiadiazole-3-yl）pyridines were synthesized. Their structures were confirmed by IR, ^1H NMR spectroscopies and elemental analysis. Their electrochemical behavior and cyclic voltammogram also were be studied. The results showed that they have high ionization potentials and good affinity.     

Spectrometric study ofα-methylene aromatic araminenone and aminoketone

Thirteenα-methylene aromatic araminenone and fourα-methylene aromatic aminoketones were prepared by modified Mannich reaction.On the basis of isotopic labeling,a plausible way of cleavage was proposed for the formation of the M~ -17 fragment peak in the MS of theα-methylene aromatic araminenone and aminoketones.The characteristic chemical shift of the olefinic protons in ~1H NMR is also discussed.     

Studies of cluster anions C n X− (X=N,P, As,Sb, Bi) produced by laser ablation

A series of cluster anions C _n X^? are produced from laser ablation of appropriate samples, where X is selected as a group-VB element. The recorded mass spectra of these cluster anions display a drastic even/odd alternation on ion intensities: For C _n N^?, only anions with oddn can be observed; For C _n P^? and C _n As^?, cluster anions with evenn are produced but with lower signal intensities; For C _n Sb^?, the signal intensity of clusters does not show even/odd alternation; Finally, for C _n Bi^?, the intensities of cluster anions with evenn are higher than those with oddn. This parity effect can be attributed to the linear structure of the cluster anions, and the parity reversal of C _n X^? from C _n N^? to C _n Bi^? can be explained from the electronegativity decreasing of the heteroatom X as it descends in the group. The Hückel model was applied to account the structural feature of these clusters.     

A new tetrathiafulvalene–diamide cation salt with [Cu2Br4]2− anions

The title salt, bis[2,3‐bis(aminocarbonyl)‐8,9‐bis(methylsulfanyl)tetrathiafulvalenium] di‐μ‐bromido‐bis[bromidocopper(II)], (C₁₀H₁₀N₂O₂S₆)₂[Cu₂Br₄], contains 2,3‐bis(aminocarbonyl)‐8,9‐bis(methylsulfanyl)tetrathiafulvalenium radical cations, [DMT‐TTF(CONH₂)₂]^·+, and [Cu₂Br₄]²⁻ anions. The cations are associated across centres of inversion in a head‐to‐tail fashion via short face‐to‐face S...S stacking (TTF moiety). These dimers are further assembled into a one‐dimensional chain structure via interdimer double S...S contacts involving the methylsulfanyl groups. The one‐dimensional chains give rise to a two‐dimensional structure through intermolecular double N—H...O hydrogen bonds involving the amide group. The [Cu₂Br₄]²⁻ anions, which straddle centres of inversion, are located between the cation layers. Electron paramagnetic resonance measurements show a radical signal, indicating that the two TTF^·+ radicals are not completely coupled in the dimer.     

Dysfunction of Shh signaling activates autophagy to inhibit trophoblast motility in recurrent miscarriage

In early pregnancy, the placenta anchors the conceptus and supports embryonic development and survival. This study aimed to investigate the underlying functions of Shh signaling in recurrent miscarriage (RM), a serious disorder of pregnancy. In the present study, Shh and Gli2 were mainly observed in cytotrophoblasts (CTBs), Ptch was mainly observed in syncytiotrophoblasts (STBs), and Smo and Gli3 were expressed in both CTBs and STBs. Shh signaling was significantly impaired in human placenta tissue from recurrent miscarriage patients compared to that of gestational age-matched normal controls. VEGF-A and CD31 protein levels were also significantly decreased in recurrent miscarriage patients. Furthermore, inhibition of Shh signaling impaired the motility of JAR cells by regulating the expression of Gli2 and Gli3. Intriguingly, inhibition of Shh signaling also triggered autophagy and autolysosome accumulation. Additionally, knockdown of BECN1 reversed Gant61-induced motility inhibition. In conclusion, our results showed that dysfunction of Shh signaling activated autophagy to inhibit trophoblast motility, which suggests the Shh pathway and autophagy as potential targets for RM therapy.Subject terms: Embryology, Endocrine reproductive disorders, Autophagosomes     

Copper oxide nanocrystals

It is well-known that inorganic nanocrystals are a benchmark model for nanotechnology, given that the tunability of optical properties and the stabilization of specific phases are uniquely possible at the nanoscale. Copper (I) oxide (Cu(2)O) is a metal oxide semiconductor with promising applications in solar energy conversion and catalysis. To understand the Cu/Cu(2)O/CuO system at the nanoscale, we have developed a method for preparing highly uniform monodisperse nanocrystals of Cu(2)O. The procedure also serves to demonstrate our development of a generalized method for the synthesis of transition metal oxide nanocrystals. Cu nanocrystals are initially formed and subsequently oxidized to form highly crystalline Cu(2)O. The volume change during phase transformation can induce crystal twinning. Absorption in the visible region of the spectrum gave evidence for the presence of a thin, epitaxial layer of CuO, which is blue-shifted, and appears to increase in energy as a function of decreasing particle size. XPS confirmed the thin layer of CuO, calculated to have a thickness of approximately 5 A. We note that the copper (I) oxide phase is surprisingly well-stabilized at this length scale.