脉冲激光法连续制备高蓝光荧光性的修饰纳米ZnO乙醇溶胶

采用聚焦脉冲激光束轰击浸于含有水杨酸的无水乙醇流动相中的ZnO固体靶, 连续制备得到了强度高达1.12×105的蓝色荧光(440 nm)的水杨酸修饰纳米ZnO乙醇溶胶. 考察了修饰剂的种类、浓度、添加顺序和流动相流速对其荧光性能的影响. 透射电镜结果表明, 所制备的纳米ZnO粒径分布在15—30 nm.     

掺杂纳米TiO2：乙醇溶胶脉冲激光法连续制备及荧光特性

采用聚焦脉冲激光轰击(PLA)浸于流动乙醇中不同金属氧化物掺杂的二氧化钛固体靶，连续制备得到一系列经MoO₃、Eu₂O₃、Fe₂O₃、WO₃等掺杂的新型纳米TiO₂乙醇溶胶。UV-Vis、荧光光谱和XRD结果表明：在所研究的掺杂纳米TiO₂乙醇溶胶中，MoO₃掺杂使纳米TiO₂乙醇溶胶荧光增强最大，当MoO₃掺杂量(ψ)在0.02%～0.50%时，其掺杂的纳米TiO₂乙醇溶胶荧光强度增强，掺杂量为0.05%时荧光强度高达1.3×10⁴(a.u.)；此外发现与sol-gel掺杂法相比，预研磨混合掺杂能更明显增强纳米TiO₂乙醇溶胶荧光。     

八肋游仆虫中心蛋白N-端半分子与Tb3+，Ca2+的结合

用分子生物学方法表达、纯化了游仆虫中心蛋白及N-端半分子，用铽荧光探针法、离子竞争法研究了pH 7.4，0.01 mol· L^-1 Hepes条件下中心蛋白与铽、钙的结合性质。结果表明中心蛋白有4个铽结合部位，其中2个为高亲合结合部位、2个为低亲合结合部位。具有2个低亲合结合部位的中心蛋白半分子与铽结合的条件常数是(2.13±0.10)×10⁵ L·mol^-1，与钙结合的条件常数是(7.52±0.02)×10² L·mol^-1。     

温度对铽(Ⅲ)-转铁蛋白溶液构象的影响

在pH 7.4,0.01 mol/L N-2-羟乙基哌嗪-N′-2-乙磺酸(Hepes)条件下,铽(Ⅲ)与N,N′-二(2-羟苄基)乙二胺-N,N′-二乙酸(HBED)结合并发生交换相互作用使铽(Ⅲ)荧光增强104倍,通过监测铽(Ⅲ)545 nm荧光强度的变化测定了Tb-HBED配合物的条件稳定常数是lgK=14.30±0.49;Tb-HBED配合物中配体、铽(Ⅲ)荧光强度均随着温度的升高而降低.在pH 7.4,0.01 mol/L Hepes条件下,TbN-apoTf-Tbc配合物中蛋白质的荧光强度随着温度的升高而降低,而能量受体铽(Ⅲ)的荧光强度随着温度的升高而增强,主要源于铽(Ⅲ)与螺旋5色氨酸残基间的无辐射能量转移;当温度由0℃上升到55℃时,平均能量转移效率AE值增加了29%,给体、受体间距离R有约4.2%的减小,温度变化引起TbN-apoTf-Tbc配合物大的构象变化;铽(Ⅲ)与人血清脱铁转铁蛋白的结合使蛋白质的变性温度降低.同样条件下,TbN-apoOTf-Tbc配合物与TbN-apoTf-Tbc配合物有所不同,虽然能量给体的荧光强度随着温度的增加而减小,但铽(Ⅲ)荧光强度没有明显的增强;铽(Ⅲ)对蛋白质的变性温度几乎没有影响.     

脉冲激光法制备修饰纳米Eu_2O_3/聚苯胺导电杂化薄膜

采用聚焦脉冲激光法(PLA-IT/SFL)制备修饰纳米Eu2O3/聚苯胺有机溶胶及其杂化薄膜材料。考察了制备条件对修饰纳米Eu2O3/聚苯胺有机溶胶荧光性能的影响。TEM显示Eu2O3粒子粒径约为15 nm且其在聚苯胺中有较高的稳定性。荧光光谱表明该杂化薄膜材料在紫外光照射下发出强烈的红光,且荧光强度达2.53×105a.u。杂化薄膜材料的电导率为1.13×10-2S.cm-1。热分析表明该杂化薄膜比导电性聚苯胺(PAN-HCSA)薄膜具有更好的热稳定性。该杂化薄膜材料可望用于电致发光领域。     

以2-氯苯甲酸、5,5′-二甲基-2,2′-联吡啶构筑的双核铽配合物的晶体结构和荧光性质

水热条件下采用Tb(NO3)3.6H2O,2-氯苯甲酸和5,5′-二甲基-2,2-联吡啶作为反应物合成出一个双核铽金属配合物Tb2(2-cb)4(dmpy)2(NO3)2(2-cb=2-氯苯甲酸,dmpy=5,5′-二甲基-2,2′-联吡啶)(1),并分别用元素分析,红外光谱图,差热分析和X-射线单晶衍射等表征了该结构。晶体结构分析结果表明:化合物1为双核铽髥配合物,通过分子间的C-H…O氢键作用,双核分子进一步被连接成二维平面结构。热稳定性表明化合物1能够稳定到280℃;荧光分析表明常温固态下配合物1发射绿色荧光,荧光寿命为431.8μs。     

铽(Ⅲ)与PvdA作用的光谱研究

Pyoverdine A(PvdA)是荧光假单胞菌分泌的一种水溶性较高的黄绿色荧光铁载体。在50mmol·L^-1Tris-HCl,pH8.0条件下,使用紫外-可见吸收差光谱、荧光光谱研究了铽(Ⅲ)与荧光铁载体PvdA的结合。结果表明铽(Ⅲ)可与PvdA结合形成1：1的配合物,条件结合常数为(4.44±0.82)×10¹⁴mol^-1·L。在生理条件下,PvdA可竞争伴清蛋白N-,C-端结合的铽(Ⅲ)形成Tb-PvdA配合物;Tb-PvdA与荧光假单胞菌细胞表面受体FpvA结合形成Tb-PvdA-FpvA复合物。     

HPLC手性流动相添加剂法拆分美索巴莫对映体

建立了以羧甲基-β-环糊精(CM-β-CD)作为手性流动相添加剂,高效液相色谱拆分美索巴莫对映体的方法。在C18色谱柱上,系统考察了手性添加剂的种类及浓度、有机修饰剂的种类及含量、流动相p H值和流速等因素对拆分的影响,确定了最佳色谱分离条件:流动相为甲醇-乙腈-水(体积比为25∶63∶12),CM-β-CD浓度为0.6 g·L~(-1),pH=4.16(用三乙胺-冰乙酸调节),流速为0.4 m L·min~(-1),检测波长为220 nm。该方法拆分美索巴莫对映体,方法简便、经济、重现性好。     

疏水性对溶胶-凝胶SiO2薄膜抗真空污染及抗激光损伤能力的影响

以正硅酸乙酯作为前驱体, 利用碱催化方式制备了SiO₂溶胶, 通过在溶胶中添加含疏水基团(-CH₃)的六甲基二硅氮烷(HMDS)对溶胶进行改性, 使用添加不同物质的量比HMDS改性后的溶胶用提拉法在K9基片上镀膜, 获得了具有疏水性能的SiO₂薄膜。采用自制接触角测量仪、紫外-可见-近红外分光光度计研究了薄膜的水接触角和透过率。测试了薄膜的激光损伤阈值, 并观察了激光辐照后薄膜的损伤形貌。通过真空污染实验对薄膜的抗污染能力及抗激光损伤能力进行了研究。实验结果表明:经疏水改性的溶胶所镀制的薄膜激光损伤阈值由未改性样品的24.3 J·cm^-2增加到37 J·cm^-2(1 064 nm, 10 ns), 且抗真空污染能力大大加强:在真空环境下保存168 h后, 未改性样品的峰值透过率下降了2%, 而疏水改性后的样品峰值透过率仅下降了0.25%, 并保持了较高的激光损伤阈值(30.8 J·cm^-2)。     

二氧化硅栅绝缘层的制备与表面修饰

研究了有机薄膜晶体管的二氧化硅栅绝缘层的性质。二氧化硅绝缘层的制备采用热生长法，氧化气氛是O₂(g)+H₂O(g)，工艺为干氧-湿氧-干氧的氧化过程。制得的绝缘层漏电流在10^-9 A左右。以该二氧化硅作为有机薄膜晶体管的栅绝缘层，并五苯作为有源层制作了有机薄膜晶体管器件。实验表明采用十八烷基三氯硅烷(OTS)进行表面修饰的器件具有OTS/SiO₂双绝缘层结构，可以有效地降低SiO₂栅绝缘层的表面能并改善表面的平整度。修饰后器件的场效应迁移率提高了1.5倍、漏电流从10^-9 A降到10^-10 A、阈值电压降低了5 V、开关电流比从10⁴增加到10⁵。结果显示具有OTS/SiO₂双绝缘层的器件结构能有效改进有机薄膜晶体管的性能。     

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.