Noncentrosymmetric K2Mn3(SO4)3F2·4H2O and Rb2Mn3(SO4)3F2·2H2O with pseudo-KTP structures

Two fluoride sulfates,K₂Mn₃(SO₄)₃F₂·4H₂O(Ⅰ) and Rb₂Mn₃(SO₄)₃F₂·2H₂O (Ⅱ) are obtained by water solution method.Single-crystal X-ray diffraction analysis indicated that they crystallize in space groups of Cmc2_1.Their structures feature a pseudo-KTP structure consisting of interconnecting[Mn₃(SO₄)3F₂(H₂O)2]_∞ layers,which are further packing along the a axis with alkali metal cations balancing the charges.The structure relationships between the two compounds are discussed.Secondharmonic generation measurements manifest that Ⅰ and Ⅱ have similar second-harmonic generation responses of about 0.2 and 0.25 times that of KH₂PO₄.     

ZrOCl2·8H2O catalyzed solvent-free synthesis of isobenzofuran-1（3H）-ones

ZrOCl₂·8H₂O catalyzed environmentally benign synthesis of isobenzofuran-1（3H）-ones are described.ZrOCl₂·8H₂O appeared to be an excellent catalyst for the condensation and reactions.Reaction of phthalaldehydic acid（2-carboxybenzaldehyde） with methylaryl and cyclic ketones was initiated by condensation and occurred in one step providing excellent yields（90-98%）.     

Cyanido-bridged one-dimensional systems assembled from [ReⅣCl4（CN）2]2- and [MⅡ（cyclam）]2+ （M=Ni,Cu） precursors

Three new cyanido-bridged heterometallic ReIVNiII and ReIVCuII one-dimensional systems were synthesized and extensively characterized both structurally and magnetically. Single-crystal X-ray diffraction analysis revealed that these compounds display a common topology, with chains composed of alternating [ReⅣCl4(CN)2]2- and [MⅡ(cyclam)]2+ (M = Ni in 1, Cu in 2) or [CuⅡ(N,N′-dimethylcyclam)]2+ (in 3) building units. Two different chain orientations with a tilt angle of ca. 51° to 55° are present in the crystal packing of these compounds. The magnetic susceptibility measurements suggest the presence of intrachain ferromagnetic interactions between the S = 3/2 ReIV centers and the 3d metal ions: S = 1 NiII or S = 1/2 CuII. At low temperature, a three-dimensional ordered magnetic phase induced by interchain antiferromagnetic interactions (antiferromagnetic for 1 and 2; canted antiferromagnetic for 3) is detected for the three compounds.     

Nickel and indium core-shell co-catalysts loaded silicon nanowire arrays for efficient photoelectrocatalytic reduction of CO2 to formate

Developing an efficient artificial photosynthetic system for transforming carbon dioxide and storing solar energy in the form of chemical bonds is one of the greatest challenges in modern chemistry.However,the limited choice of catalysts with wide light absorption range,long-term stability and excellent selectivity for CO₂ reduction makes the process sluggish.Here,a core-shell-structured nonnoble-metal Ni@In co-catalyst loaded p-type silicon nanowire arrays(SiNWs)for efficient CO₂ reduction to formate is demonstrated.The formation rate and Faradaic efficiency of formate over the Ni@In/SiNWs catalyst reach 58μmol h^-1 cm^-2 and 87% under the irradiation of one simulated sunlight(AM 1.5 G,100 mW cm^-2),respectively,which are about 24 and 12 times those over the pristine SiNWs.The enhanced photoelectrocatalytic performance for CO₂ reduction is attributed to the rational combination of Ni capable of effectively extracting the photogenerated electrons and In responsible for the selective activation of CO₂.     

Synthesis of High-purity Fe2AlB2 and the Effect as Sintering Additive for ZrB2

Fe₂AlB₂ powder material was prepared by the direct reaction of iron,aluminum and boron powders in a tubular furnace.The effects of different Al contents,temperature and raw material pretreatment on the purity of product were studied.The mixed powder with the stoichiometric ratio of 1.5Al/2Fe/2B was processed by CIP (Cold Isostatic Pressing),and then calcined at 1150℃ for 120 min.The product containing a small amount of impurities is treated with alkaline solution to obtain high-purity Fe₂Al B₂ powder.Zr B₂-Fe₂Al B₂ composite ceramic was successfully prepared at 1250℃ by hot pressing sintering.The density,hardness and fracture toughness were 96.2%,22±0.3 GPa and 5.78±0.5 MPa·m^1/2,respectively.     

ZnMn3O7: A New Layered Cathode Material for Fast-Charging Zinc-Ion Batteries

Low-cost and high-energy-density manganese-based compounds are promising cathode materials for rechargeable aqueous zinc-ion batteries（AZIBs）, however, they often experience cycling instability issues and inferior rate capability. Herein, we report a new layered manganese-based cathode material, ZnMn₃O₇（ZMO）, which possesses a large interlayer spacing of 4.8 ? and allows the intercalation of ～1.23 Zn-ions per formula unit（corresponding to a capacity of ～170 m Ah/g）. Importa...     

2D spinel ZnCo2O4 microsheet-coated functional separator for promoted redox kinetics and inhibited polysulfide dissolution

Lithium-sulfur(Li-S)batteries are receiving increasing attention as one of the potential next-generation batteries,owing to their high energy densities and low cost.However,practical Li-S batteries with high energy densities are extremely hindered by the sulfur loss,low Coulombic efficiency,and short cycling life originating from the polysulfide(LiPS)shuttle.In this study,two-dimensional(2D)ZnCo₂O₄ microsheets fabricated by a facile hydrothermal process are employed to modify the separator,for improving the electrochemical performances of Li-S cells.The resulting 2D Zn Co₂O₄-coated separator features a coating thickness of approximately 10 lm,high ionic conductivity of 1.8 m S/cm,and low mass loading of 0.2 mg/cm².This 2D ZnCo₂O₄-coated separator effectively inhibits Li PS shuttle by a strong chemical interaction with Li PS as well as promotes the redox kinetics by Zn CO2O4-coated layers,as determined by X-ray photoelectron spectroscopy analysis,self-discharge,time-dependent permeation test,Li symmetric cell test,and Li2S nucleation analyses.Consequently,the Li-S batteries based on the 2D Zn Co₂O₄-coated separator exhibit a high initial discharge capacity of 1292.2 m Ah/g at 0.1 C.Moreover,they exhibit excellent long cycle stability at 1 and 2 C with capacity retention of 84%and 86%even after800 cycles,corresponding to a capacity fading rate of 0.020%and 0.016%per cycle,respectively.Effectively,these Li-S cells with a high sulfur loading at 5.3 mg/cm² and low electrolyte concentration of 9 l L/mg deliver a high discharge capacity of 4.99 m Ah/cm² after 200 cycles at 0.1 C.     

From aqueous Zn-ion battery to Zn-MnO2 flow battery:A brief story

Aqueous Zn-ion battery(AZIB)has become an attractive technology because of its unique features of low cost,high safety and the eco-friendliness.MnO₂ is the model cathode material for AZIB since the first report on reversible Zn-MnO₂ battery,but recent studies have unveiled different charge storage mechanisms.Due to revamping of the electrochemistry and redesigning of the electrolyte and interface,there is tremendous performance enhancement in AZIB.This mini Review will first give a brief introduction of ZIB,including fundamentals of materials and components,and the progress in recent years.Then,a general classification of working mechanisms related to MnO₂ in neutral and mildly acidic electrolyte is elaborated.Our focus is put on the recent blossoming Zn-MnO₂ electrolytic mechanism,which has given birth to the Zn-MnO₂ redox flow batteries that are highly promising for large-scale static energy storage.     

KAl（SO4）2·12H2O catalyzed efficient synthesis of 3,4,6-trisubstituted 2-pyridone in water

An efficient green protocol for the preparation 3,4,6-trisubstituted 2-pyridone of employing a condensation reaction of cyanoacetamide and acetylacetone in the presence of KAl（SO₄）₂·12H₂O in water has been described.The present procedure offers advantage such as shorter reaction time,simple workup,and excellent yields.     

Enhanced catalytic performance for direct synthesis of dimethyl ether from syngas over a La2O3 modified Cu-ZrO2/γ-Al2O3 hybrid catalyst

A series of hybrid catalysts were made by physically mixing Cu-ZrO 2 and γ-Al 2 O 3,for former it was modified with different loadings of La 2 O 3 prepared by co-precipitation method.The catalysts were characterized by BET,XRD,N 2 O-adsorption,EXAFS,H 2-TPR,NH 3-TPD techniques and evaluated in the synthesis of dimethyl ether from syngas.The results show that La 2 O 3 promoted catalysts displayed a significantly better catalytic performance compared with Cu-ZrO 2 /γ-Al 2 O 3 catalyst in CO conversion and DME selectivity,and the optimum catalytic activity was obtained when the content of La 2 O 3 was 12 wt%.The characterizations reveal that high copper dispersion,facile reducibility of copper particles and appropriate amount of acidic sites are responsible for the superior catalytic performance.     

氯代烷烃、硫粉和氢亚磷酸酯一步合成S-烷基硫磷酸酯

S-苄基硫磷酸酯和S-烷基硫磷酸酯在农药中有着重要的应用。 本文发展了一种无需催化剂,仅在碱作用下,氯代烷烃、硫粉以及氢亚磷酸酯三组份一步生成S-烷基硫磷酸酯的绿色经济方法,该反应可以在一步反应中同时构建磷—硫键和碳—硫键。 以苄氯及衍生物、硫粉、氢亚磷酸酯在碳酸铯的促进下,室温反应,共合成了17个S-苄基硫磷酸酯,产率为70%~99%。 同时,实现了脂肪链的氯代烃、硫粉和氢亚磷酸酯的反应,在三乙胺的促进下,在空气中60 ℃反应,共合成了13个S-烷基硫磷酸酯,产率为45%~93%。 本方法在合成上和工业上将具有较好的应用前景。     

Homochiral cyclopentane-based C1-symmetric P,P ligands C5H8(PPh2)(PR2) from C2-symmetric C5H8(PCl2)2

Treatment of 1,2-trans-C₅H₈(PCl₂)₂ with 1,2-C₂H₄(NHPr-i)₂ gave the C₂-symmetric perhydro-1,6,2,5-diazaphosphocine C₅H₈{P(Cl)N(Pr-i)CH₂}₂-cyclo, which produced dissymmetric C₅H₈(PPh₂){P[N(Pr-i)CH₂]₂-cyclo} on further reaction with PhMgBr. Cleavage of the P---N bonds with gaseous HCl afforded C₅H₈(PPh₂)(PCl₂), which was converted to C₅H₈(PPh₂){P(OPh)₂}₂ by reaction with phenol. All chiral P,P derivatives were obtained as racemates as well as resolved (1R,2R)- and (1S,2S)-enantiomers.     

Indenyl complexes of ruthenium(II) containing optically active diphosphines. X-ray structures of (S,S)-(η-C9H7)-Ru{Ph2PCH(CH3)CH(CH3)PPh2}Cl and of its η-C5H5 analogue

The optically active indenyl complexes ((η⁵-C₉H₇)Ru(L---L)Cl (where L---L is either (S,S)-1,2-dimethyl-1,2-ethanediylbis(diphenylphosphine) (chiraphos) or (R,R)-1,2-cyclopentanediylbis(diphenylphosphine) (cypenphos)) have been synthesized and spectroscopically characterized and compared with the corresponding cyclopentadienyl complexes. Reaction of the new complexes with 2-e-donors give cationic adducts in which the pentahaptocoordination of the indenyl ligand is maintained. The crystal structures of (S,S)-(η⁵-C₉H₇)Ru{Ph₂PCH(CH₃)CH(CH₃)PPh₂}Cl (1) and (S,S)-η⁵-C₅H₅Ru{Ph₂PCH(CH₃)CH(CH₃)PPh₂}Cl (3) have been determined.     

Heat capacity and thermodynamic properties of N-(2-cyanoethyl) aniline (C9H10N2)

The low temperature heat capacities of N-(2-cyanoethyl)aniline were measured with an automated adiabatic calorimeter over the temperature range from 83 to 353 K. The temperature corresponding to the maximum value of the apparent heat capacity in the fusion interval, molar enthalpy and entropy of fusion of this compound were determined to be 323.33 ± 0.13 K, 19.4 ± 0.1 kJ mol⁻¹ and 60.1 ± 0.1 J K⁻¹ mol⁻¹, respectively. Using the fractional melting technique, the purity of the sample was determined to be 99.0 mol% and the melting temperature for the tested sample and the absolutely pure compound were determined to be 323.50 and 323.99 K, respectively. A solid-to-solid phase transition occurred at 310.63 ± 0.15 K. The molar enthalpy and molar entropy of the transition were determined to be 980 ± 5 J mol⁻¹ and 3.16 ± 0.02 J K⁻¹ mol⁻¹, respectively. The thermodynamic functions of the compound [H_T − H_298.15] and [S_T − S_298.15] were calculated based on the heat capacity measurements in the temperature range of 83–353 K with an interval of 5 K.     

Synthesis of Pt compounds containing chiral (2S,4S) -pentane-2,4-diyl-bis(5H-dibenzo[b]phosphindole) as ligand and their use in asymmetric hydroformylation of styrene derivatives

Unlike bis(diphenyl)phosphine derivatives in general, (2S,4S)-pentane-2,4-diyl-bis(5H-dibenzo[b]phosphindole), S,S-BDBPP, gives a trans oligomeric compound [PtCl₂(S,S-BDBPP)]_n, 1, in reaction with dichloro-Pt precursors such as PtCl₂(PhCN)₂, PtCl₂(CH₃CN)₂ and PtCl₂(COD) at room temperature. Compound 1, which could be readily isolated, slowly rearranges in solutions at room temperature to the expected cis-monomer PtCl₂(S,S-BDBPP), 3. Heating or the presence of PtCl₂(COD) accelerates the transformation of compound 1 to 3. SnCl₂ adducts of both compounds, trans-[PtCl(SnCl₃)(S,S-BDBPP)]_n, 2, and cis-PtCl(SnCl₃)(S,S-BDBPP), 4, as well as the known cis-PtCl(SnCl₃)(S,S-BDPP), 5, (S,S-BDPP = (2S,4S)-2,4-bis(diphenylphosphino)pentane) have been tested as catalysts in the asymmetric hydroformylation of p-isobutylstyrene. The phenyl analog 5 provides up to 75% e.e. but moderate yields to chiral 2-(4-isobutylphenyl)-2-propanal. Compared to this, the regioselectivity to the branched aldehyde is remarkably increased; however, the enantioselectivity is drastically decreased by the use of both dibenzophosphole derivatives 2 and 4. The similarities in the selectivities provided by 2 and 4 indicate that the trans oligomer 2 transforms to the cis-monomer 4 during the catalytic process. X-ray crystal structure determination of compound 3 shows a half-chair conformation for the chelate ring with a symmetric arrangement of dibenzophosphole groups. Besides a preference for the latter achiral conformation, the planar structure of the dibenzophosphole groups can also be considered as reason for the moderate enantioselectivities provided by 4.     

Asymmetric hydroformylation with Pt-phosphine-SnCl2 and Pt-bisphosphine-CuCl2 (or CuCl) catalytic systems

A study has been made of asymmetric hydroformylation of styrene with PtCl₂(PPh₃)₂ + bisphosphine + SnCl₂ (bisphosphine: BDPP = (−)-(2S,4S)-2,4-bis(diphenylphosphino)pentane or DIOP = (−)-(4R,5R)-2,2-dimethyl-4,5-bis(diphenylphosphinomethyl)-1,3-dioxolane) and PtCl₂(bisphosphine) + PPh₃ + SnCl₂ catalysts prepared “in situ”. The presence of an excess of the phosphine ligand slightly lowered the reaction rate, but the enantioselectivity of these systems is significantly higher than those involving PtCl(SnCl₃)(bisphosphine) catalysts. Under mild reaction conditions 88.8% enantiomeric excess was achieved. Replacing SnCl₂ in these catalysts by CuCl₂ or CuCl gave a new homogeneous catalytic system which is active at higher reaction temperature (> 100°C), but has a rather moderate enantioselectivity.     

Magnetic investigation of Cu(NH3)4(NO3)2

The magnetic properties of Cu(NH₃)₄(NO₃)₂ have been measured at low temperatures. Broad maxima in both the susceptibility and specific heat are observed and are consistent with linear chain behavior of a Heisenberg antiferromagnet, with J/k = 3.9 ± 0.1 K. Long-range order sets in at T_c = 0.15 ± 0.01 K, and the ratio kT_c/|J| = 0.038 is the lowest observed as yet for a one-dimensional, S = 1/2 antiferromagnet.     

Stereoselectivities in AgBF4-catalyzed and photoinduced phenyl-rearrangement of 2-chloropropiophenone

(S)-2-Phenylpropionic acid was stereoselectively obtained by the AgBF₄-catalyzed phenyl-rearrangement of (S)-2-chloropropiophenone dimethyl acetal, while the photoirradiation of (S)- or (R)-2-chloropropiophenone afforded partially racemized (S)- or (R)-2-phenylpropionic acid, respectively. An intramolecular S_N2 mechanism is suggested for the former rearrangement. The latter result is indicative of the intervention of an ion or radical intermediate in the photoinduced phenyl-rearrangement.     

凹凸棒黏土负载纳米TiO2-Fe3O4吸附剂的制备及Cr(Ⅵ)的脱除

采用溶胶-凝胶法、一锅反应法制备了负载纳米TiO₂和Fe₃O₄的凹凸棒黏土(TiO₂-Fe₃O₄-ATP)吸附剂,并进行了模拟废水中Cr(Ⅵ)的吸附及脱附性能的研究。 通过扫描电子显微镜(SEM)、X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)和EDS等分析方法对ATP负载纳米TiO₂-Fe₃O₄前后结构进行了表征,考察了物料配比及吸附时间、pH值、温度、投加量和初始质量浓度对Cr(Ⅵ)吸附率的影响。 结果表明,吸附剂在Ti元素含量与负载总量的摩尔比为3：4时吸附效果最佳。 当吸附剂质量为0.6 g,Cr(Ⅵ)离子初始质量浓度小于0.8 mg/L时,pH=6,温度20 ℃,吸附剂对Cr(Ⅵ)的吸附率为79.8%。 TiO₂-Fe₃O₄-ATP吸附剂对Cr(Ⅵ)离子吸附满足Freundlich模型。 在20~40 ℃ 条件下,吸附过程ΔG<0、ΔS=-43.55 J/(mol·K)、ΔH=-14.36 kJ/mol,表明该吸附是个自发、熵减、放热的过程。 吸附过程符合准二级动力学模型,吸附速率控制步骤以表面化学反应为主。 TiO₂-Fe₃O₄-ATP吸附剂在循环使用4次后,吸附率仍能达到65%以上。     

Synthesis of (2R,3S,4S)-4-aryl-3-hydroxyprolinols

Synthesis of (2R,3S,4S)-4-aryl-3-hydroxyprolinols has been established starting from 2-benzyloxymethylpyrrolidin-2-one framework, which is derived from commercially available trans-(2S,4R)-4-hydroxyproline. The single diastereomer having a trans–cis relative configuration with C₂ and C₃ and C₃ and C₄ is constructed in two one-pot functional group transformations of Grignard addition/dehydration and epoxidation/isomerization as the key steps in moderate yield.