碳酸盐共沉淀法可控制备超高倍率锂离子电池正极材料LiNi1/3Co1/3Mn1/3O2

采用碳酸盐共沉淀法通过调节NH₃·H₂O用量来实现可控制备超高倍率纳米结构LiNi_1/3Co_1/3Mn_1/3O₂正极材料。NH₃·H₂O用量会对颗粒的形貌、粒径、晶体结构以及材料电化学性能产生较大的影响。X射线衍射（XRD）分析和扫描电镜（SEM）结果表明,随着NH₃·H₂O用量的降低,一次颗粒形貌由纳米片状逐渐过渡到纳米球状,且n_NH3·H2O：（n_Ni+n_Co+n_Mn）=1：2样品晶体层状结构最完善、Li⁺/Ni²⁺阳离子混排程度最低。电化学性能测试结果也证实了n_NH3·H2O：（n_Ni+n_Co+n_Mn）=1：2样品具有最优异的循环稳定性和超高倍率性能。具体而言,在2.7~4.3 V,1C下循环300次后的放电比容量为119 mAh·g^-1,容量保持率为81%,中值电压基本无衰减（保持率为97%）。在100C（18 Ah·g^-1）的超高倍率下,放电比容量还能达到56 mAh·g^-1,具有应用于高功率型锂离子电池的前景。此NH₃·H₂O比例值对于共沉淀法制备其他高倍率、高容量的正/负极氧化物材料具有一定的工艺参考价值。     

氧杂蒽染料修饰钴-硫脲配合物的光解水放氢性能

将具有不同端基的硫脲基团与三苯基磷组分结合,利用所得到的配体合成了2个具有NSP（氮硫磷）鳌合位点的钴-硫脲化合物,并研究了其光解水产氢性能。配合物[Co（L2）（L2''）]（BF₄）_2.5·H₂O·0.5C₂H₅OH（2）（L2=（2-二苯基膦-苯烯基）-氨基硫脲腙-罗丹明6G,L2''=（2-二苯基膦氧-苯烯基）-氨基硫脲腙-罗丹明6G）通过引入罗丹明荧光团与光敏剂分子协同作用,其产氢TON值可以达到2800 mol_H2·mol^-1_cat,其初始TOF值可达到930 mol_H2·mol^-1_cat·h^-1。相同条件下,相比于配合物[Co（L1）（L1''）]（BF₄）·0.5H₂O（1）（L1=（2-二苯基膦-苯烯基）-氨基硫脲腙-硫甲基,L1''=（2-二苯基膦氧-苯烯基）-氨基硫脲腙-硫甲基）,提高了体系的催化活性,可能是由于荧光素分子与配合物2之间的分子间π-π堆积作用有利于光敏剂和光催化剂之间的光致电子转移。     

α-Ti(HPO4)2微球负载型催化剂的合成及其烯烃聚合催化性能

2种茂金属催化剂及1种后过渡金属催化剂分别被固载于经过甲基铝氧烷处理后的α-Ti（HPO₄）₂微球表面,制备得到3种微球负载型催化剂。在烯烃聚合反应过程中,3种负载型催化剂均表现出比硅胶负载型催化剂更高的催化活性。2种茂金属负载型催化剂在乙烯、丙烯聚合反应中的活性分别高达6.8×10⁷ g_PE·（mol_Zr·h）^-1和5.0×10⁷ g_PP·（mol_Zr·h）^-1,所产生的烯烃聚合产物分子量分布较窄（M_w/M_n<2.3）,表现出良好的单中心催化特性,而且丙烯聚合产物的等规度高达96.5%。负载型后过渡金属催化剂在乙烯聚合反应中的活性稍低,但也能够达到8.3×10⁶ g_PE·（mol_Fe·h）^-1。3种负载型催化剂催化烯烃聚合产物均成微球型,能够很好地复制载体的形貌。     

α-Ti(HPO4)2微球负载型催化剂的合成及其烯烃聚合催化性能

2种茂金属催化剂及1种后过渡金属催化剂分别被固载于经过甲基铝氧烷处理后的α-Ti（HPO₄）₂微球表面,制备得到3种微球负载型催化剂。在烯烃聚合反应过程中,3种负载型催化剂均表现出比硅胶负载型催化剂更高的催化活性。2种茂金属负载型催化剂在乙烯、丙烯聚合反应中的活性分别高达6.8×10⁷ g_PE·（mol_Zr·h）^-1和5.0×10⁷ g_PP·（mol_Zr·h）^-1,所产生的烯烃聚合产物分子量分布较窄（M_w/M_n<2.3）,表现出良好的单中心催化特性,而且丙烯聚合产物的等规度高达96.5%。负载型后过渡金属催化剂在乙烯聚合反应中的活性稍低,但也能够达到8.3×10⁶ g_PE·（mol_Fe·h）^-1。3种负载型催化剂催化烯烃聚合产物均成微球型,能够很好地复制载体的形貌。     

基于3,5-二(氧乙酸基)苯甲酸构建的多核锰(Ⅱ)配位聚合物的合成、晶体结构和氧化-还原性质

采用1,3-二（4-吡啶基）丙烷为模板剂,水热法合成了3个以3,5-二（氧乙酸基）苯甲酸（H₃BOABA）为配体的多核Mn（Ⅱ）配位聚合物：{（H₃O）[Mn₄（BOABA）₂（OH）₃（H₂O）]·H₂O}_n（1）,{（H₃O）₄[Mn₇（BOABA）₄（OH）₆（H₂O）₂]}_n（2）,{（H₃O）₄[Mn₇（BOABA）₄（OH）₄（Cl）₂（H₂O）₂]·2H₂O}_n（3）。通过X射线衍射,元素分析、红外光谱和热重分析进行了结构表征。结构分析表明,1为正交Pbcm空间群,由四核锰簇单元[Mn₄（μ₃-OH）₃（COO）₁₀]构成具有（5,12）-连接的3D网络结构,拓扑符号为（3².4⁷.5）₂（3⁸.4²³.5¹⁴.6²¹）。配位聚合物2与3为异质同构化合物,属正交Ccma空间群,分别由七核锰簇单元[Mn₇（OH）₆（COO）₁₆]和[Mn₇（OH）₄Cl₂（COO）₁₆]构成的具有（3,12）-连接的2D网络结构,拓扑符号为（4³）₄（4³⁰.6²⁴.8¹²）。测定了聚合物的氧化-还原电位。     

基于3,5-二(氧乙酸基)苯甲酸构建的多核锰(Ⅱ)配位聚合物的合成、晶体结构和氧化-还原性质

采用1,3-二（4-吡啶基）丙烷为模板剂,水热法合成了3个以3,5-二（氧乙酸基）苯甲酸（H₃BOABA）为配体的多核Mn（Ⅱ）配位聚合物：{（H₃O）[Mn₄（BOABA）₂（OH）₃（H₂O）]·H₂O}_n（1）,{（H₃O）₄[Mn₇（BOABA）₄（OH）₆（H₂O）₂]}_n（2）,{（H₃O）₄[Mn₇（BOABA）₄（OH）₄（Cl）₂（H₂O）₂]·2H₂O}_n（3）。通过X射线衍射,元素分析、红外光谱和热重分析进行了结构表征。结构分析表明,1为正交Pbcm空间群,由四核锰簇单元[Mn₄（μ₃-OH）₃（COO）₁₀]构成具有（5,12）-连接的3D网络结构,拓扑符号为（3².4⁷.5）₂（3⁸.4²³.5¹⁴.6²¹）。配位聚合物2与3为异质同构化合物,属正交Ccma空间群,分别由七核锰簇单元[Mn₇（OH）₆（COO）₁₆]和[Mn₇（OH）₄Cl₂（COO）₁₆]构成的具有（3,12）-连接的2D网络结构,拓扑符号为（4³）₄（4³⁰.6²⁴.8¹²）。测定了聚合物的氧化-还原电位。     

3,3''-(吡啶-3,5)二苯甲酸构筑的Co(Ⅱ)/Ni(Ⅱ)配合物的合成、晶体结构及性质

设计、合成了2个配合物：{[Co₂（pddb）₂（μ₂-H₂O）（H₂O）₂]·2DMA·5H₂O}_n（1）和{[Ni₂（pddb）₂（μ₂-H₂O）（H₂O）₂]·2DMA·5H₂O}_n（2）（H₂pddb=3，3''-（吡啶-3，5）二苯甲酸，DMA=N，N-二甲基乙酰胺），并通过红外光谱（IR），元素分析，热重分析（TG）和单晶X射线衍射确定它们的结构。结构分析表明1和2是异质同构的，其空间构型可简化成（3，6）连接的拓扑结构，其符号为（4²·6）·（4⁴·6²·8⁸·10）。进一步研究了配合物1和2的固体紫外、磁性及其催化性能。研究表明1和2中的中心金属离子之间存在反铁磁耦合作用，并且1可以作为C-H活化的高效非均相催化剂。     

Cr2O3和CrO3/Cr2O3催化剂的2-氯-1，1，1-三氟乙烷气相氟化反应的活性物种和失活

采用沉淀法和浸渍法制备了2种铬基（Cr₂O₃和CrO₃/Cr₂O₃）催化剂,用于气相氟化2-氯-1,1,1-三氟乙烷合成1,1,1,2-四氟乙烷。研究发现含有低价铬（Cr³⁺）物种的Cr₂O₃催化剂上2-氯-1,1,1-三氟乙烷的稳态转化率为18.5%,而含有高价铬（Cr⁶⁺）物种和低价铬（Cr³⁺）物种的CrO₃/Cr₂O₃催化剂初始转化率达到30.6%,然而存在明显的失活。含有Cr⁶⁺物种的CrO₃/Cr₂O₃催化剂的2-氯-1,1,1-三氟乙烷氟化反应初始TOF值为1.71×10^-4 mol_HCFC-133a·mol_Cr(Ⅵ)^-1·s^-1,高于含有Cr³⁺物种的Cr₂O₃催化剂（4.16×10^-5 mol_HCFC-133a·mol_Cr(Ⅲ)^-1·s^-1）。Cr₂O₃催化剂在氟化反应前后催化剂的物相结构保持不变;而含有高价铬物种的CrO₃/Cr₂O₃催化剂经HF反应后生成了CrO_xF_y活性物种。然而,CrO_xF_y物种在反应中挥发或转化成稳定但无活性的CrF₃,从而导致催化剂失活。     

氧杂蒽染料修饰钴-硫脲配合物的光解水放氢性能

将具有不同端基的硫脲基团与三苯基磷组分结合,利用所得到的配体合成了2个具有NSP（氮硫磷）鳌合位点的钴-硫脲化合物,并研究了其光解水产氢性能。配合物[Co（L2）（L2''）]（BF₄）_2.5·H₂O·0.5C₂H₅OH （2）（L2=（2-二苯基膦-苯烯基）-氨基硫脲腙-罗丹明6G,L2''=（2-二苯基膦氧-苯烯基）-氨基硫脲腙-罗丹明6G）通过引入罗丹明荧光团与光敏剂分子协同作用,其产氢TON值可以达到2 800 mol_H2·mol_cat^-1,其初始TOF值可达到930 mol_H2·mol_cat^-1·h^-1。相同条件下,相比于配合物[Co（L1）（L1''）]（BF₄）·0.5H₂O （1）（L1=（2-二苯基膦-苯烯基）-氨基硫脲腙-硫甲基,L1''=（2-二苯基膦氧-苯烯基）-氨基硫脲腙-硫甲基）,提高了体系的催化活性,可能是由于荧光素分子与配合物2之间的分子间π-π堆积作用有利于光敏剂和光催化剂之间的光致电子转移。     

2-吡啶甲醇和1,1,1-三羟甲基乙烷混合配体七核锰配合物的合成、晶体结构与磁性

四水合氯化锰、2-吡啶甲醇和1,1,1-三羟甲基乙烷在乙腈里反应合成出一个七核Mn簇合物[Mn₃^ⅡMn₄^Ⅲ(Cl)₆(hmp)₆(thme)₂]·H₂O·3CH₃CN(1·H₂O·3CH₃CN,hmpH为2-吡啶甲醇, thmeH3为三羟甲基乙烷),并对该化合物进行X射线衍射单晶结构分析、元素分析、红外光谱和磁性研究。1·H₂O·3CH₃CN属于单斜晶系I2/a空间群,配合物核骨架可看成由交替的Mn^Ⅱ和Mn^Ⅲ离子形成一个六边形,而这个六边形又围绕在1个Mn^Ⅲ离子的周围,这种结构类型的配合物以前并没有报道过。磁性研究表明,化合物1·H₂O中Mn^Ⅲ与Mn^Ⅱ或Mn^Ⅲ与Mn^Ⅲ离子之间总体是铁磁性耦合的,交流磁化率研究发现该化合物有弱的频率依赖现象。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.