Self-Assembly of Macrocyclic Boronic Esters Bearing Tellurophene Moieties and Their Guest-Responsive Phosphorescence

Guest-controlled diastereoselective self-assembly of a diboryltellurophene and a chiral tetrol bearing an indacene backbone was achieved to give either hetero- or homochiral macrocyclic boronic esters, selectively. The heterochiral isomer (hetero-[2+2]^Te) exhibited a higher inclusion ability for electron-deficient aromatic guests, leading to effective quenching of phosphorescence from the diboryltellurophene moieties. The reported macrocycles collectively represent a promising arene sensing approach based on phosphorescence.     

Supramolecular Photocatalysis by Utilizing the Host–Guest Charge-Transfer Interaction: Visible-Light-Induced Generation of Triplet Anthracenes for [4+2] Cycloaddition Reactions

Supramolecular photocatalysis via charge-transfer excitation of a host–guest complex was developed by use of the macrocyclic boronic ester [2+2]_BTH-F containing highly electron-deficient difluorobenzothiadiazole moieties. In the presence of a catalytic amount of [2+2]_BTH-F, the triplet excited state of anthracene was generated from the charge-transfer excited state of anthracene@[2+2]_BTH-F by visible-light irradiation, and cycloaddition of the excited anthracene with several dienes and alkenes proceeded in a [4+2] manner in high yields.     

Photo-promoted Skeletal Rearrangement of Phosphine–Borane Frustrated Lewis Pairs Involving Cleavage of Unstrained C−C σ-Bonds

An unprecedented photo-promoted skeletal rearrangement reaction of phosphine–borane frustrated Lewis pairs, o-(borylaryl)phosphines, involving cleavage of an unstrained sp²C–sp³C σ-bond is reported. The reaction realizes an efficient synthesis of cyclic phosphonium borate compounds. The reaction mechanism via a boranorcaradiene intermediate is proposed based on theoretical calculations. This work sheds light on the new photoreactivity of phosphine–borane FLPs.     

Heavy ion physics with the ATLAS detector

The European Physical Journal C - Recent results from RHIC experiments suggest that a hot and dense QCD matter, which maybe the quark gluon plasma (QGP), is formed in Gold+Gold collisions at a...     

High-performance liquid chromatographic analysis of ginsenosides inPanax ginseng extracts using glass-ODS column

Summary Octadecyl-porous glass was prepared and used as the packing for reversed-phase high-performance liquid chromatography. A mixture of ginsenosides, saponins of ginseng was analyzed with detection at 203 nm. Ginsenosides Rf, Rg₂, Rb₁, Rc, Rb₂, and Rd were separated with acetonitrile-water (27.5:72.5) as the mobile phase. A well-resoluted chromatogram of ginsenosides Ro, Rg₁ and Re was also obtained with acetonitrile-water (16.5:83.5). The whole separation was achieved in 12 min with a flowrate of 1 ml/min. Calibration curves of ginsenosides Rb₁, Rc, Rb₂, Rd, Rg₁ and Re were linear up to 5 μg. It can be concluded that the rapid and accurate analysis of ginsenosides is possible by the described method.     

Chromatographic separation and identification of human urine components

Summary Ultraviolet-absorbing components of human urine were separated by HPLC with a large scale column (250 × 28 mm I.D. stainless-steel) containing a macroreticular type strongly basic anion-exchange resin. The sample was eluted with a linear gradient of 0.006 M to 6.0 M ammonium acetate buffer (pH 4.40) and different fractions were collected. The identification of one compound using ultraviolet, infrared and mass spectral data is illustrated; it was found to be uric acid.     

Stereoselective iodocyclopropanation of terminal alkenes with iodoform, chromium(II) chloride, and N,N,N',N'-tetraethylethylenediamine

Chemoselectivity of a reagent for (E)-olefination of aldehydes derived by reduction of iodoform with chromium(II) chloride in THF changes markedly by addition of TEEDA (N,N,N',N'-tetraethylethylenediamine), and trans-iodocyclopropanes are produced stereoselectively from terminal alkenes by treatment with the base-added reagent system. The iodocyclopropanation occurs only at terminal double bonds, and di- and trisubstituted double bonds in the same molecules remained unchanged. Such functional groups as alcohol, ether, silyl ether, ester, tertiary amine, and amide groups are compatible with the reaction conditions.     

Structure and properties of Bi2Sr2CaCu2Ox/Bi2Sr2CuOx superlattices prepared by RF magnetron sputtering

We have prepared Bi₂Sr₂CaCu₂O_x/Bi₂Sr₂CuO_x (2212/2201) superlattices with various stacking periodicity by multitarget RF magnetron sputtering. Their crystal structure and electrical properties were investigated. The superlattice was found to be successfully constructed from the data of XRD patterns, AES, etc. The critical temperature increased almost linearly with increasing thickness of the 2212 phase up to a thickness of 6 unit cells. On the other hand, it did not decrease as the thickness of the 2201 layers was increased. The unit cell/unit cell superlattice showed T_{c zero} of 30 K.