Single Atoms of Iron on MoS2 Nanosheets for N2 Electroreduction into Ammonia

Efforts have been devoted to achieving a highly efficient artificial synthesis of ammonia (NH₃). Reported herein is a novel Fe-MoS₂ catalyst with Fe atomically dispersed onto MoS₂ nanosheets, imitating natural nitrogenase, to boost N₂ electroreduction into NH₃ at room temperature. The Fe-MoS₂ nanosheets exhibited a faradic efficiency of 18.8 % with a yield rate of 8.63 μg mg_cat.⁻¹ h⁻¹ for NH₃ at −0.3 V versus the reversible hydrogen electrode. The mechanism study revealed that the electroreduction of N₂ was promoted and the competing hydrogen evolution reaction was suppressed by decorating the edge sites of S in MoS₂ with the atomically dispersed Fe, resulting in high catalytic performance for the electroreduction of N₂ into NH₃. This work provides new ideas for the design of catalysts for N₂ electroreduction and strengthens the understanding about N₂ activation over Mo-based catalysts.     

Four New Lariciresinol‐Based Lignan Glycosides from the Roots of Rhus javanica var. roxburghiana

The four new lariciresinol‐based lignan glycosides, (?)‐lariciresinol 4′‐(6″‐O‐feruloyl‐β‐D ‐glucopyranoside) ( 1 ), (?)‐lariciresinol 4′‐(4″,6″‐di‐O‐feruloyl‐β‐D ‐glucopyranoside) ( 2 ), 5,5′‐dimethoxylariciresinol 4′‐(4″,6″‐di‐O‐feruloyl)‐β‐D ‐glucopyranoside) ( 3 ), and 4‐O‐[α‐(1,2‐dihydroxyethyl)syringyl]‐5,5′‐dimethoxylariciresinol 4′‐(4″,6″‐di‐O‐feruloyl‐β‐D ‐glucopyranoside) ( 4 ), together with two known ones, lariciresinol 4′‐β‐D ‐glucopyranoside) ( 5 ) and tortoside B ( 6 ), were isolated from the BuOH extract of Rhus javanica var. roxburghiana roots, and their structures were established by means of various spectroscopic techniques.     

Reactivity of organolanthanide and organolithium complexes containing the guanidinate ligands toward isocyanate or carbodiimide: synthesis and crystal structures

The direct reactions of (C5H5)2LnCl with LiN=C(NMe2)2 proceeded at room temperature in THF under pure nitrogen to yield the lanthanocene guanidinate complexes [(C5H5)2Ln(mu-eta1:eta2-N=C(NMe2)2)]2 (Ln = Gd (1), Er (2)). Treatment of phenyl isocyanate with complexes 1 and 2 results in monoinsertion of phenyl isocyanate into the Ln-N(mu-Gua) bond to yield the corresponding insertion products [(C5H5)2Ln(mu-eta1:eta2-OC(N=C(NMe2)2)NPh)]2 (Ln = Gd (3), Er (4)), presenting the first example of unsaturated organic small molecule insertion into the metal-guanidinate ligand bond. Further investigations indicate that N,N'-diisopropylcarbodiimide does not react with complexes 1 and 2 under the same conditions; however, it readily inserts into the lithium-guanidinate ligand bond of LiN=C(NMe2)2. As a synthon of the insertion product Li[(iPrN)2C(N=C(NMe2)2)], its reaction with (C5H5)2LnCl gives the novel organolanthanide complexes containing the guanidinoacetamidinate ligand, (C5H5)2Ln[(iPrN)2C(N=C(NMe2)2)] (Ln = Yb (5), Er (6), Dy (7)). All complexes were characterized by elemental analysis and spectroscopic properties. The structures of complexes 1, 3, 5 and 7 were determined through X-ray single-crystal diffraction analysis.     

Studies of synergism for lowering dynamic interfacial tension in sodium alpha-(n-alkyl) naphthalene sulfonate/alkali/acidic oil systems

Alkylnaphthalene sulfonates with high purity were selected as model components to research synergism for lowering interfacial tension (IFT) in surfactant/alkali/acidic oil systems. The dynamic IFTs between alkylnaphthalene sulfonates with different alkyl chain length and n-decane, oleic acid model oil, or Shengli crude oil were measured. The results showed that the alkylnaphthalene sulfonates with different alkyl chain lengths had different synergism with different acidic components and their ionized acids under the same conditions. The synergism for lowering dynamic IFT in alkylnaphthalene sulfonate/alkali/acidic oil systems was controlled by alkylnaphthalene sulfonate concentration, alkyl chain length, alkali concentration, alkali type, and oleic acid concentration: optimal physicochemical conditions were necessary to the best synergism. This indicates that the synergism among added surfactant acidic components in crude oil and their ionized acids is controlled by the ratio of their interfacial concentrations.     

Voltammetric Reduction of alpha- and gamma-[S2W18O62]4- and alpha-, beta-, and gamma-[SiW12O40]4-: isomeric dependence of reversible potentials of polyoxometalate anions using data obtained by novel dissolution and conventional solution-phase processes

Comparative studies on the voltammetric reduction of the alpha and gamma isomers of Dawson [S(2)W(18)O(62)](4)(-) and alpha, beta, and gamma forms of Keggin [SiW(12)O(40)](4)(-) polyoxometalate anions have been undertaken. For the six reversible one-electron [S(2)W(18)O(62)](4)(-)(/5)(-)(/6)(-)(/7)(-)(/8)(-)(/9)(-)(/10)(-) processes in acetonitrile, reversible potentials (E(0)(')) were found to be independent of isomeric form within experimental error (+/-5 mV). However, because both the alpha and gamma* isomers of [Bu(4)N](4)[S(2)W(18)O(62)] are insoluble in water, solid-state voltammetric studies with microcrystals adhered to electrode surfaces in contact with aqueous Et(4)NCl and Bu(4)NCl electrolyte media were also possible. Although no isomeric distinction was again detected in the solid-state studies, it was found that reduction of adhered solid by four or more electron equivalents led to rapid dissolution. When Et(4)NCl was the electrolyte, this dissolution process coupled with potential cycling experiments enabled conventional solution-phase data to be obtained in water for the analogous six one-electron reduction steps previously detected in acetonitrile. A strong medium effect attributed to Lewis acidity effects was apparent upon comparison with E(0)(') data obtained in water and acetonitrile. In contrast, with the [SiW(12)O(40)](4)(-) system, E(0)(') values for the [SiW(12)O(40)](4)(-)(/5)(-)(/6)(-)(/7)(-) processes in acetonitrile exhibited a larger (about 70 mV) dependence on isomeric form, and the isomerization step, [gamma-SiW(12)O(40)](6)(-)--> [alpha-SiW(12)O(40)](6)(-), was detected on the voltammetric time scale. The influence of isomeric form on reversible potential data is considered in terms of structural and charge density differences exhibited in the [S(2)W(18)O(62)](4)(-) and [SiW(12)O(40)](4)(-) systems studied in this paper and published data available on the alpha, beta, gamma, and gamma isomers of [As(2)W(18)O(62)](6)(-) and [P(2)W(18)O(62)](6)(-) Dawson anions and Keggin systems.     

ETC and Thermal Ligand Substitution in PhCCo3(CO)9 with 2,3-Bis(diphenylphosphino)-N-phenylmaleimide(bppm). X-Ray Diffraction Structure of Co3(CO)6[μ2,η2, η1-C(Ph)(O)](μ2-PPh2)

The reactivity of the bidentate ligand 2,3-bis(diphenylphosphino)-N-phenylmaleimide (bppm) with the tetrahedrane cluster PhCCo₃(CO)₉ under thermolysis and ETC conditions has been studied and found to ultimately give Co₃(CO)₆[μ₂,η²,η¹-C(Ph) ${\text{C}}{\text{ = }}{\text{ = }}{\text{C(PPh}}_{\text{2}} {\text{)C(O)NPhC}}$ (O)](μ₂-PPh₂) as the final product. The intermediate cluster compound PhCCo₃(CO)₇(bppm), which was observed by IR and ³¹P NMR spectroscopies, readily and rapidly transforms into the product cluster under the reactions conditions. The solid-state structure of Co₃(CO)₆[μ₂,η²,η¹-C(Ph)fptt(O)](μ₂-PPh$_{2})$ was unequivocally determined by X-ray crystallography. Co₃(CO)₆[μ₂, η², η¹-C(Ph)Õ(O)](μ₂-PPh₂) crystallizes in the monoclinic space group P2(1)/n, a = 11.825(5) Å, b = 31.20(1) Å, c = 11.831(5) Å, β = 108.720(7)°, V = 4134(7) ų, Z = 4, d _calc = 1.567 Mg/m³; R = 0.0350, R _w = 0.0817 for 4747 observed reflections with I > 2σ(I). The X-ray structure confirms the coupling of the benzylidyne ligand with the bppm ligand in Co₃(CO)₆[μ₂,η²,η¹-C(Ph)Õ(O)](μ₂-PPh₂). The course of the thermolysis reaction is identical to those reactions carried out with the related diphosphine ligands bma and bpcd. The utility of electron-transfer catalysis (ETC) in the preparation of PhCCo₃(CO)₇(bppm) is discussed relative to the reduction potential of the bppm ligand and the tricobalt cluster PhCCo₃(CO)₉.     

Synthesis, crystal structure and magnetic property of the novel dinuclear nickel(II) complex with 4-(p-methoxyphenyl)-3,5-bis(pyridine-2-yl)-1,2,4-triazole

A novel dinuclear nickel(II) complex, [Ni₂(MOBPT)₂Cl₂(H₂O)₂]Cl₂ · 7H₂O (MOBPT = 4-(p-methoxyphenyl) −3,5-bis(pyridine-2-yl)-1,2,4-triazole), has been synthesized and characterized by elemental analysis, IR and single crystal X-ray diffraction methods. The crystal structure determination shows that the dinuclear Ni₂N₈ unit is almost planer in which each Ni^II ion is coordinated by four nitrogen atoms from MOBPT equatorially and a water molecule and a chloride ion axially in a distorted octahedral geometry. Magnetic measurements reveal a relatively weak antiferromagnetic exchange in the complex.     

{[Cu4(nip)4(4，4′-bipy)4(DMF)4]·CH3OH}n配合物的合成与晶体结构

A coordination polymer, {[Cu₄(nip)₄(4，4′-bipy)₄(DMF)₄]·CH₃OH}_n, have been synthesized by the layer method using 5-nitroisophthalic acid (H₂nip), Cu(CH₃COOH)₂ and 4,4′-bipyridine(4,4′-bipy) with three solutions in a marrow tube and structurally characterized by X-ray single-crystal structure analysis. The results indicated that the nip ligand has a μ₂ mono-atomic bridging-monodentate coordination mode and the structure is a two-dimensional network. CCDC: 623420.     

The Synthesis of Gracillin and Dioscin：TWO Typical Representatives of Spirostanol Glycosides

Two spirostanol saponins(gracillin and dioscin)which have the typical sugar moieties were synthesized facilely by a general approach.     

微量元素锌与反复呼吸道感染的相关性

对28例反复呼吸道感染患儿(下称复感儿)及26例健康儿进行微量元素发锌测定。发现前者发锌平均值为(92.3±14.7)×10~(-6),后者为(132.5±21.5)×10~(-6),P<0.01,差异非常显著。对复感儿进行口服锌治疗,观察其疗效及治疗前后发锌变化。治疗前发锌平均值为(92.3±14.7)×10~(-6),治疗后为(137.5±20.2)×10~(-6),P<0.01差异非常显著。有效率达85.7％。故缺锌可能是复感儿患病的影响因素之一,锌治疗小儿反复呼吸道感染是十分必要的。