碳纳米管复合微球修饰L-色氨酸及其对LDL的吸附性能

本文以多孔碳纳米管/活性炭复合微球为载体, 以L-色氨酸为配基, 采用环氧氯丙烷偶联法, 制得修饰L-色氨酸的碳纳米管/活性炭复合微球(L-CNTs/AC)。采用扫描电镜、氮气吸附、傅立叶红外光谱、热分析、X射线光电子能谱等对复合微球进行表征;通过体外静态吸附法对其低密度脂蛋白(LDL)吸附能力进行初步研究。结果表明:环氧氯丙烷偶联法可接枝上L-色氨酸。复合微球中碳纳米管加入量越多, 对LDL的吸附能力越强;当碳纳米管加入量为45wt%时, 对LDL的吸附量达4.623 mg·g^-1, 是未添加碳纳米管的2.3倍多。这是因为碳纳米管不仅可促进复合微球中20~100 nm孔的形成, 而且还可促进复合微球配基修饰量的增多, 从而大大增强了复合微球对LDL的吸附能力。此复合微球可望开发成一种新型的血液灌流LDL吸附剂。     

富氮多级孔炭材料的制备及其吸附分离CO2的性能

使用新型含氮聚合物席夫碱为炭源, SBA-15为模板,通过纳米铸型法原位合成微孔-中孔-大孔串联的多级孔富氮炭材料.材料的比表面积为752 m²·g^-1,孔容0.79 cm³·g^-1; X光电子能谱分析表明炭材料中的氮含量高达7.85%(w).将所制备的多孔炭材料应用于CO₂的吸附分离,发现炭材料的微孔发挥主导作用,表面氮掺杂发挥辅助作用.在两者的协同作用下, CO₂吸附量在常压、273 K下可达97 cm³·g^-1, CO₂/N₂和CO₂/CH₄的分离比(摩尔比)分别为7.0和3.2,低压亨利吸附选择性分别为23.3和4.2.采用Toth模型对单组分平衡吸附进行拟合,并根据理想溶液吸附理论(IAST)预测双组分CO₂/N₂和CO₂/CH₄混合气体的分离选择性分别为40和18.     

磺化碳纳米管/活性炭复合微球的制备及其对低密度脂蛋白的吸附性能

采用悬浮聚合、炭化、活化制得碳纳米管/活性炭复合微球; 而后利用重氮盐偶合法将对氨基苯磺酸接枝到此复合微球上, 得到磺化碳纳米管/活性炭复合微球; 将其用于吸附血清中的低密度脂蛋白(LDL). 结果表明: 所制备的磺化碳纳米管/活性炭复合微球球形度好, 表面光洁, 中孔发达, 并且接枝有对氨基苯磺酸. 此复合微球对LDL的吸附量随着碳纳米管加入量的增加而逐渐增大; 当碳纳米管加入量为45% (w)时, LDL吸附量达6.564 mg·g^-1, 是未添加碳纳米管的3.3倍. 此复合微球在作为血液灌流LDL吸附剂方面有较好的应用前景.     

锂离子电池用非晶态Si/Al/Si薄膜负极材料

采用磁控溅射法在铜箔集流体上沉积了具有“三明治”结构的Si/Al/Si三层薄膜. 高分辨率透射电镜(HRTEM)和选区电子衍射(SAED)分析结果表明, 该薄膜为非晶态. 扫描电镜(SEM)和能量散射X射线能谱(EDS)结果表明, 该薄膜总厚度约为4.0 μm, 循环100周后体积膨胀率为225％. 在1.5~0.005 V(vs. Li+/Li)和0.1 mA/cm2条件下, 该薄膜电极前5周衰减较快, 而后趋于平缓. 首次放锂量为0.88 mA·h/cm2, 循环5周后, 放锂量为0.71 mA·h/cm2, 100周后的放锂量仍能保持在0.61 mA·h/cm2. 研究结果表明, Al的加入有效地抑制了Si膜的体积膨胀, 使之具有良好的循环寿命. 交流阻抗结果表明, 随着循环次数的增加, 极化电阻首先从46.9 Ω·cm2(第1周)降低到36.2 Ω·cm2(第50周), 而后又升高到47.3 Ω·cm2(第100周). Al的加入提高了Si膜的导电性, 有效地降低了其极化电阻, 改善了Si膜的电压滞后现象.     

温度对Zn(II)-TiO2体系吸附可逆性的影响

用延展X射线吸收精细结构光谱(EXAFS)研究了不同温度对Zn(II)-锐钛矿型TiO2吸附产物微观构型和吸附可逆性的影响机制. 宏观的吸附-解吸实验表明, 不同温度下的吸附等温线可以用Langmuir 模型进行较好的描述(R2≥0.990). 随温度升高, 吸附等温线显著升高, Zn(II)在TiO2表面的饱和吸附量由5 ℃时的0.125 mmol·g-1增至40 ℃时的0.446 mmol·g-1; 而体系的不可逆性明显减弱, 解吸滞后角θ由32.85°减至8.64°. 求得体系反应的热力学参数⊿H、⊿S分别为24.55 kJ·mol-1 和159.13 J·mol-1·K-1. EXAFS结果表明, Zn(II)主要是通过共用水合Zn(II)离子及TiO2表面上的O原子结合到TiO2表面上,其平均Zn-O原子间距为RZn-O=(0.199±0.001) nm. 第二配位层(Zn-Ti 层)的EXAFS图谱分析结果表明, 存在两个典型的Zn-Ti 原子间距, 即R1=(0.325±0.001) nm (边-边结合的强吸附)和R2=(0.369±0.001) nm(角-角结合的弱吸附). 随温度升高, 强吸附比例(CN1)基本不变而弱吸附比例(CN2)增加, 两者比值(CN1/CN2)逐渐减小. 该比值的变化从微观角度解释了宏观实验中温度升高, 不可逆性减弱的吸附现象.     

铝离子和钛离子化学改性MCM-41介孔材料的制备及其对污水中镉离子的吸附性能(英文)

通过在MCM-41材料中引入Al 3+和Ti 4+两种诱因金属离子合成了化学改性介孔材料Al-Ti-MCM-41和Ti-Al-MCM-41;评价了两种介孔材料对污水中镉离子的吸附行为.利用氮气吸附-脱附等温线对Al-Ti-MCM-41(1∶1)样品的吸附行为进行了详细分析,考察了吸附剂投加量、Cd2+初始质量浓度和吸附温度对其吸附行为的影响.结果表明:改性Al-Ti-MCM-41(1∶1)介孔材料的最可几孔径和比孔容分别为16nm和0.04cm3/g,由BJH法计算得到的平均孔径为17.02nm;其对污水中Cd2+的吸附率达99.8%.Cd2+的吸附率随Al-Ti-MCM-41(1∶1)介孔材料投加量的增加先增加而后降低最终达到平衡,吸附容量随Cd2+初始浓度的增大而增加;吸附温度对吸附行为基本无影响.     

等离子体原子发射光谱法研究纳米Al2O3材料对稀土离子(La3+、Eu3+和Yb3+)的吸附行为

采用等离子体原子发射光谱法(ICP-AES)为检测手段,以纳米Al2O3为吸附材料,系统地研究了其在静态条件下对稀土离子(La3+、Eu3+和Yb3+)的吸附性能,确定了最佳吸附及解脱条件.实验结果表明,在pH=8.0～9.0范围内,分析物可被定量吸附,用1.0 mol·L-1盐酸溶液可将吸附的稀土离子完全解脱.本方法对La3+、Eu3+和Yb3+的检出限分别为10.2 ng·mL-1、5.2 ng·mL-1和1.7 ng·mL-1,相对标准偏差(RSD)分别为3.9%、4.2%和2.9%(n=11,c=0.5μg·mL-1).所得实验数据显示,该吸附材料的吸附容量比色谱用氧化铝高2～3倍.     

甲烷水蒸气重整催化剂上水吸附性能的研究

用程序升温脱附技术(TPD)研究了工业上常用的甲烷水蒸气重整催化剂的载体,镍催化剂和添加重稀土氧化物助剂(RE_2O_3)的镍催化剂上水的吸附性能。结果表明,水在碱性载体(CaO·Al_2O_3,CaO·2Al_2O_3,MgO·Al_2O_3)(以下简称A_2)上的吸附量比在酸性载体(α-Al_2O_3)(以下简称A_1)上吸附量约大80%;在Ni-A_2上的吸附量比在Ni-A_1催化剂上的约大10%;而在Ni-RE_2O_3-A_1和Ni-RE_2O_3-A_2上的吸附量比在相应的Ni-A_1和Ni-A_2分别大35%和38%左右。催化剂上水吸附量的大小与它在甲烷水蒸气反应中抗积炭性能的好坏相一致。测得水在A_2载体上的吸附热为224kJ/mol(280—380℃);水在Ni-RE_2O_3-A_2催化剂上的平均吸附热为46kJ/mol(110—280℃)。     

碳纳米管复合微球修饰L-色氨酸及其对LDL的吸附性能

本文以多孔碳纳米管/活性炭复合微球为载体,以L-色氨酸为配基,采用环氧氯丙烷偶联法,制得修饰L-色氨酸的碳纳米管/活性炭复合微球(L-CNTs/AC)。采用扫描电镜、氮气吸附、傅立叶红外光谱、热分析、X射线光电子能谱等对复合微球进行表征;通过体外静态吸附法对其低密度脂蛋白(LDL)吸附能力进行初步研究。结果表明:环氧氯丙烷偶联法可接枝上L-色氨酸。复合微球中碳纳米管加入量越多,对LDL的吸附能力越强;当碳纳米管加入量为45wt%时,对LDL的吸附量达4.623 mg·g-1,是未添加碳纳米管的2.3倍多。这是因为碳纳米管不仅可促进复合微球中20~100 nm孔的形成,而且还可促进复合微球配基修饰量的增多,从而大大增强了复合微球对LDL的吸附能力。此复合微球可望开发成一种新型的血液灌流LDL吸附剂。     

金属-有机骨架材料MOF-5的改进与吸附甲烷的巨正则蒙特卡罗模拟

根据金属-有机骨架材料(MOFs)的设计思想, 在MOF-5(对苯二甲酸为桥联配体, Zn4O金属簇为中心的配位化合物)的基础上设计了10 种以Zn4O 金属簇为中心(Corner), 以不同基团单取代的对苯二甲酸(BDC)衍生物为桥联配体(Linker)的多孔材料. 用巨正则蒙特卡罗(GCMC)模拟方法, 计算了这些材料在298 K、1-10 MPa条件下对甲烷的吸附量, 讨论了不同取代基与甲烷吸附量的关系.结果发现, 在298 K、3.5 MPa 时甲烷的吸附量主要取决于吸附热, 并且以硝基取代的配体构成的MOF分子吸附甲烷效果最好. 在此基础上, 进一步设计了以四硝基取代对苯二甲酸为桥联配体的MOF-4NO2, 该结构在相同条件下对甲烷的超额吸附量为209 cm3·cm-3, 总吸附量达到228 cm3·cm-3, 比美国能源部(DOE)提出的甲烷吸附材料应用要求标准高26%.     

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%.     

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.     

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.     

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.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

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.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.