RExOy.nH2O对氟离子的吸附性能

La、Ce等稀土水含氧化物对阴离子的吸附性早有研究「‘－‘1，但从混合轻稀土氯化物制得的水合氧化物吸附F一的研究报道较少．为探讨难溶金属水合氧化物的除氟性能，本文以混合轻稀土氯化物为原料，制得其水含氧化物（RExOy·nH。O），采用高聚物造粒，研究了粒状RExOy·nH。O对F一的吸附性能及吸附机理．所用混合轻稀土氯化物由包头钢铁稀土公司提供，其主要组成（以氧化物计）为：CeO。（50％）、Nd。O3（25％）、La。O。（15％）、P36Oll（8％）．聚丙烯睛分子量为（2．5～5）X10‘．其它试剂为分析纯．RExO．·nH。O参照文…     

On-surface isostructural transformation from a hydrogen-bonded network to a coordination network for tuning the pore size and guest recognition

Rational manipulation of supramolecular structures on surfaces is of great importance and challenging. We show that imidazole-based hydrogen-bonded networks on a metal surface can transform into an isostructural coordination network for facile tuning of the pore size and guest recognition behaviours. Deposition of triangular-shaped benzotrisimidazole (H₃btim) molecules on Au(111)/Ag(111) surfaces gives honeycomb networks linked by double N–H⋯N hydrogen bonds. While the H₃btim hydrogen-bonded networks on Au(111) evaporate above 453 K, those on Ag(111) transform into isostructural [Ag₃(btim)] coordination networks based on double N–Ag–N bonds at 423 K, by virtue of the unconventional metal–acid replacement reaction (Ag reduces H⁺). The transformation expands the pore diameter of the honeycomb networks from 3.8 Å to 6.9 Å, giving remarkably different host–guest recognition behaviours for fullerene and ferrocene molecules based on the size compatibility mechanism.

A hydrogen-bonded network on a Ag(111) surface can transform into an isostructural Ag(i) coordination network, giving drastically different host–guest recognition behaviours.     

Highly efficient visible-light photocatalytic ethane oxidation into ethyl hydroperoxide as a radical reservoir

Photocatalytic ethane conversion into value-added chemicals is a great challenge especially under visible light irradiation. The production of ethyl hydroperoxide (CH₃CH₂OOH), which is a promising radical reservoir for regulating the oxidative stress in cells, is even more challenging due to its facile decomposition. Here, we demonstrated a design of a highly efficient visible-light-responsive photocatalyst, Au/WO₃, for ethane oxidation into CH₃CH₂OOH, achieving an impressive yield of 1887 μmol g_cat⁻¹ in two hours under visible light irradiation at room temperature for the first time. Furthermore, thermal energy was introduced into the photocatalytic system to increase the driving force for ethane oxidation, enhancing CH₃CH₂OOH production by six times to 11 233 μmol g_cat⁻¹ at 100 °C and achieving a significant apparent quantum efficiency of 17.9% at 450 nm. In addition, trapping active species and isotope-labeling reactants revealed the reaction pathway. These findings pave the way for scalable ethane conversion into CH₃CH₂OOH as a potential anticancer drug.

Highly efficient visible-light driven photocatalytic oxidation of ethane into ethyl hydroperoxide was realized for the first time over Au/WO₃.     

Zig‐Zag Diphosphene Oligomers Linked by Silver(I) Cation

The coordination of silver cation to diphosphene Mes*P=PMes* ( 1 , Mes* = ^tBu₃C₆H₂) was investigated in detail. The reaction of 1 with Ag[Al(OR_F)₄] (OR_F = OC(CF₃)₃) in the ratios of 2 : 1, 3 : 2 and 1 : 2 led to the formation of the first cationic silver linked diphosphene complexes 2 — 4 . Complexes 2 and 3 contain two and three diphosphene molecules linked by the linear Ag(I) cation, respectively, and they feature unusual zig‐zag topologies. Complex 4 is a dinuclear silver complex, and each Ag(I) center features a tetrahedral geometry, coordinated by one phosphorus atom of diphosphene 1 and three chloro atoms of two CH₂Cl₂ molecules.     

Cover Picture: Electrochemical Oxidative Csp3—H/S—H Cross‐Coupling with Hydrogen Evolution for Synthesis of Tetrasubstituted Olefins (Chin. J. Chem. 6/2019)

The inside cover picture shows an electrochemical oxidative Csp³‐H/S‐H activation with hydrogen evolution for the synthesis of tetrasubstituted olefins. This method features very high atom economy, besides hydrogen gas, under the base‐free, transition met‐al‐free, and oxidants‐free conditions, no other by‐products were generated. More details are discussed in the article by Lei et al. on page 547–551.

     

On Mercury(I) Oxo Compounds — Quasi‐Relativistic Computational and Experimental Studies

About 60 molecular species composed of up to 10 mercury atoms and of oxygen atoms and/or of some other elements or groups (such as halogen, OH₂, OH, H, alkali, NO₃) have been investigated quantum chemically. Different density functional approaches and the ab initio SCF‐MP2 method were applied, comparing different basis sets and different atomic core sizes. It is important not to treat the Hg 5s, p, d as inactive core shells, and to use sufficiently many polarization functions. The shape of the 〉O‐Hg‐Hg‐O〈 units is not favorable concerning the formation of lattices composed of Hg^I, O and OH only. Despite its bulkiness, the OHgHgO units can easily come into contact with each other and then disproportionate. This is prevented in the so‐called ternary M‐Hg^I oxides by the embedded oxometallate (oxoacidic) anions. Furthermore, the Hg^I and Hg^II oxide bond energies are less favorable towards the stability of Hg^I oxo compounds, as compared to Hg halidic or oxoacidic compounds. Both points are not promising concerning the search for Hg^I oxides/hydroxides, although the preparation of such compounds, including spacer groups, by topochemical reactions can still not be excluded. So far, experimental efforts towards the synthesis of such a new class of compounds have only demonstrated that Hg^II is strictly preferred over Hg^I in the formation of solids of binary Hg‐O or ternary A‐Hg‐O composition (A = electropositive metal such as alkali, in contrast to M = transition or semi‐metal). This is so even if compounds containing ‘electron rich Hg^δ— atoms’ (i.e. A‐Hg amalgams) are oxidized under mild conditions.     

Triangular halogen trimers. A DFT study of the structure, cooperativity, and vibrational properties

Triangular halogen trimers (RX)3, where X = Br, I and R represents H, H3C, H2FC, HF2C, F3C, CH2=CH, CH[triple bond]C, and Ph, have been investigated using the density functional theory in the Perdew, Burke, and Ernzerhof method. We report herein the optimized geometries of the stable structures, their vibrational frequencies, and binding energies with the two- and three-body terms. All trimer structures possess a cyclic array of halogen atoms in the type II approach by virtue of the nonspherical atomic charge distribution around the halogens. The Br...Br interactions in trimers are very weak, whereas the I...I interactions in trimers are relatively stronger. While all bromine trimers and most of iodine trimers are predicted to be noncooperative, three of iodine trimers show weak cooperativity. The analysis of vibration modes reveals that all halogen trimers exhibit no especially remarkable frequency shifts. It is also shown that the electrostatic contribution plays a major role in the halogen...halogen interactions in halogen trimers. In contrast to bromine trimers, the relative contribution of charge-transfer component to the halogen...halogen interactions becomes more important for iodine trimers.     

Further studies on synthesis of the 12,13-seco norditerpenoid alkaloids

After a series of optimization for the reaction conditions (reagents, reaction temperature, etc.), treatment of the sulfonates 4, 8, 13 and 15 with 8% NaOH (room temperature, 24 h) via a semipinacol rearrangement afforded the corresponding C-nor compounds 5, 9, 12 and 16, as the major of a pair of epimer at C-16, to an excellent extent, in 95%, 92%, 100% and 90% yield, respectively. The 12,13-seco compounds 21 and 22 (23) were obtained in 20% and 60% yield, respectively, by treating 5 with Br(2)-glacial HOAc (room temperature, 24 h). Treatment of the C-nor compounds 5 or 6, 16 or 17, and 28 from 10 with SOCl(2)-anhydrous benzene (room temperature, overnight) afforded the 12,13-seco compounds 24, 26 and 30 in 70% or 100%, 40% and 66% yield, respectively. When treatment of the C-nor compound 29 from 9 under same conditions gave the 12,13-seco products 30, 31 and 32 in 33%, 26% and 20% yield. When treating 21 or 24, and 26 with 5% KOH in EtOH afforded the 12,13-seco compounds 25 and 27 quantitatively, respectively. The compound 31 converted to 30 quantitatively by treatment with Na(2)CO(3) in MeOH. All of the new compounds were isolated and fully characterized.     

Pt／钇稳定氧化锆固体电解质在高温下的电化学性质

用交流阻抗技术研究了二电极、三电极Ｐｔ／钇稳定氧化锆（简称ＹＳＺ）高温固体电化学体系．开路电位下，Ｐｔ／ＹＳＺ体系只有一个阻抗半圆，对应于电极体系的电化学活化控制过程，极化电阻随温度变化的表观活化能为１７１．５ｋＪ／ｍｏｌ．Ｐｔ／ＹＳＺ界面的双电层电容约为３００μＦ／ｃｍ２．阳极极化下，交流阻抗极化电阻显著减小；阴极极化下，极化电阻反而增大，并出现浓差控制现象．