AgNi双金属改性多面体钒酸铋的制备及光催化性能

采用简单的水热法制备了多面体钒酸铋（BVO）材料,又通过化学还原法首次在BVO上原位合成了一种小尺寸的AgNi双金属助催化剂并研究了其光催化性能。采用X射线衍射（XRD）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、紫外可见漫反射光谱（UV-Vis DRS）、X射线光电子能谱（XPS）、光致发光（PL）光谱、N₂吸附-脱附等手段对制备的AgNi/BVO材料的理化性能进行了表征。结果表明,AgNi双金属广泛负载在这种特殊形貌的BVO多面体表面,大大增加了金属的附着位点,同时AgNi负载也提高了BVO的结晶性。银表面等离子体谐振效应与镍的共格界面效应增强了BVO催化剂对可见光的吸收,增强了光生电子的分离,提高了光催化活性。光催化降解MB （亚甲基蓝）实验表明,当Ag、Ni的质量比为3∶1时,AgNi/BVO的催化活性最高,在可见光照射下其反应速率常数是BVO的5.4倍,该光催化剂在4次循环后仍能保持良好的光催化活性。     

多孔超薄g-C_3N_4纳米片负载Pt复合材料的制备及其光催化性能（英文）

以三聚氰胺为前驱体,通过热氧化刻蚀法制备多孔超薄g-C_3N_4纳米片(CNHS),将其与氯铂酸钾溶液混合后采用原位光化学还原法成功制备了CNHS负载Pt光催化剂(Pt-CNHS)。使用粉末X射线衍射、场发射扫描电子显微镜、X射线光电子能谱、透射电子显微镜、紫外可见漫反射光谱和N_2吸附-脱附测试等技术对所制备样品的结构、形貌、光吸收特性、光电化学性能和比表面积等进行系统分析。并以气相甲苯为目标降解物,研究其光催化性能。结果表明,相对于体相g-C_3N_4(CNB)和CNHS,Pt的引入可以有效增强催化剂对可见光的吸收能力、响应范围及载流子分离效率。与纯g-C_3N_4和CNHS相比,Pt-CNHS在紫外和可见光照射下均表现出更高的光催化降解气相甲苯的活性。此外,也对Pt-CNHS光催化剂在可见光照射下降解气相甲苯的反应历程做了初步研究。     

Bi/BiVO4&Bi4V2O11复合催化剂的制备及其光催化性能

经由溶剂热反应、光辅助还原过程制备Bi/Bi VO_4Bi_4V_2O_(11)纳米复合光催化材料。通过X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、高分辨率透射电子显微镜(HRTEM)、X射线光电子能谱(XPS)、紫外-可见漫反射光谱(UV-Vis DRS)、N_2吸附-脱附等温线和光致发光(PL)等手段对该复合物进行表征。实验结果表明当金属Bi与BiVO_4Bi_4V_2O_(11)的质量比值为0.8,可见光照射30 min时,Bi/BiVO_4Bi_4V_2O_(11)复合催化剂对罗丹明B(RhB)的降解率可达95.6%。此外,Bi/BiVO_4Bi_4V_2O_(11)对四环素(TC)的降解也表现出增强的光催化性能。Bi/BiVO_4Bi_4V_2O_(11)复合材料提升的光催化性能可能归因于金属Bi的表面等离子体共振(SPR)效应、拓宽的可见光吸收范围和增大的比表面积。此外,提出了复合光催化剂可能的光催化机理。     

漂浮型BiFeO_3/膨胀珍珠岩的制备及其可见光催化性能（英文）

利用水热法制备了新颖的、漂浮型的膨胀珍珠岩(EP)负载BiFeO_3(BiFeO_3/EP)复合光催化材料。采用X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线光电子能谱仪(XPS)和紫外可见漫反射(UV-Vis-DRS)对制备的复合材料进行了表征与分析。SEM和TEM结果清楚地表明BiFeO_3纳米粒子已被负载到EP表面。与纯BiFeO_3相比,BiFeO_3/EP复合材料明显提高了对可见光的吸收能力,减小了带隙宽度,在可见光下对亚甲基蓝(MB)的降解表现出更强的光催化活性。其中,70%BiFeO_3/EP复合材料对MB染料废水的光催化活性最高,其光催化反应一级速率常数是纯BiFeO_3的2.2倍。由于质轻中空的特点,制备的BiFeO_3/EP颗粒漂浮在液面上,有利于相分离和反应后光催化剂的回收。材料的重复性试验表明,复合材料在MB光降解过程中是相当稳定的。     

施主掺杂对BaTiO3钙钛矿半导体纳米晶光催化性能的影响

以沉淀法制备的Cu_2O为牺牲模板剂,采用水热法制备La施主掺杂的BaTiO_3钙钛矿半导体纳米晶,借助X射线衍射(XRD)、透射电子显微镜(TEM)、高分辨透射电镜(HRTEM)、X射线光电子能谱((XPS)、扫描电子显微镜(SEM)、紫外-可见漫反射光谱(UV-Vis DRS)表征La掺杂的BaTiO_3晶的物相、微观形貌及光催化性能。结果表明,La掺杂BaTiO_3构建了晶体缺陷,有效提高了BaTiO_3的光催化性能。当掺杂量为4%(w/w)时,样品的光催化性能最好,在可见光照射360 min后,对4-硝基苯酚溶液的降解率可达到93.2%。该催化剂5次循环后的活性仍然大于86.7%,表明La施主掺杂的BaTiO_3是一种有效的可见光催化剂。     

Ag2O/TiO2纳米线异质结的制备及可见光催化性能

采用化学沉积法制得了氧化银/二氧化钛纳米线异质结(Ag₂O/TNWs)可见光催化剂. 应用扫描电子显微镜(SEM)、 透射电子显微镜(TEM)、 X射线衍射(XRD)和X射线光电子能谱(XPS)等手段对催化剂进行表征, 并以甲基橙降解为模型反应研究了其光催化性能. 结果表明, 与负载等量氧化银的二氧化钛纳米粒子(Ag₂O/P25)催化剂相比, Ag₂O/TNWs纳米线异质结具有优异的一维增强可见光催化性能.     

Ag负载CdMoO4光催化剂的制备及其催化性能

采用硼氢化钠还原法制备了Ag负载Cd Mo O4光催化剂。运用X射线粉末衍射(XRD)、扫描电镜(SEM)和透射电镜(TEM)等测试手段对催化剂的组成和结构进行了表征;采用紫外-可见漫反射光谱(UV-Vis DRS)和X射线光电子能谱(XPS)等技术对催化剂的光响应和表面状态进行了分析,考察了不同Ag负载量对Cd Mo O4紫外光降解罗丹明B和可见光选择性氧化苯甲醇性能的影响。结果表明,与Cd Mo O4相比,Ag/Cd Mo O4具有更高的光催化活性。利用活性物种捕获实验探讨其光催化降解过程的反应机理,实验结果显示O2-·和·OH是光催化降解过程的主要活性物种。     

溶剂热法制备Ag/TiO_2纳米材料及其光催化性能

以乙醇为溶剂,钛酸四丁酯为前驱体,用溶剂热法制备了Ag表面修饰的负载型纳米二氧化钛光催化剂.利用X射线衍射(XRD)、N2吸附-脱附(BET)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)、紫外-可见(UV-Vis)光谱等技术对其进行了系统的表征,以亚甲基蓝(MB)溶液的脱色降解为模型反应,考察了不同Ag含量样品的光催化性能.结果表明:用溶剂热法制备的样品中TiO2皆为锐钛矿相,金属Ag颗粒沉积在TiO2表面,粒径为2nm左右,比表面积较溶胶凝胶法制备的样品大大增加,最高可达151.44m2·g-1;UV-Vis光谱和光催化实验表明:Ag修饰使TiO2对光的吸收能力大大增强,吸收带边红移至可见光区,亚甲基蓝在该复合材料上的光催化降解反应遵循一级反应动力学模型;溶剂热法制备样品的光催化性能明显好于溶胶凝胶法制备的样品,在紫外光和可见光下,Ag摩尔分数为5%的样品表现出最佳的光催化活性.     

漂浮型BiFeO3/膨胀珍珠岩的制备及其可见光催化性能

利用水热法制备了新颖的、漂浮型的膨胀珍珠岩(EP)负载BiFeO₃(BiFeO₃/EP)复合光催化材料。采用X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线光电子能谱仪(XPS)和紫外可见漫反射(UV-Vis-DRS)对制备的复合材料进行了表征与分析。SEM和TEM结果清楚地表明BiFeO₃纳米粒子已被负载到EP表面。与纯BiFeO₃相比,BiFeO₃/EP复合材料明显提高了对可见光的吸收能力,减小了带隙宽度,在可见光下对亚甲基蓝(MB)的降解表现出更强的光催化活性。其中,70%BiFeO₃/EP复合材料对MB染料废水的光催化活性最高,其光催化反应一级速率常数是纯BiFeO₃的2.2倍。由于质轻中空的特点,制备的BiFeO₃/EP颗粒漂浮在液面上,有利于相分离和反应后光催化剂的回收。材料的重复性试验表明,复合材料在MB光降解过程中是相当稳定的。     

Ag/ZnO纳米纤维的制备及光催化性能

采用静电纺丝技术及煅烧法制备了氧化锌纳米纤维, 然后采用水热法将银纳米颗粒负载到了氧化锌纳米纤维表面. 利用X射线衍射(XRD)、 X射线光电子能谱(XPS)、 能量色散X射线光谱(EDX)、 扫描电子显微镜(SEM)及透射电子显微镜(TEM)等技术对合成的Ag/ZnO纳米纤维的结构和组成进行了表征. SEM结果表明, 直径在5~100 nm之间的银纳米颗粒附着在直径在80~330 nm之间的氧化锌纤维表面形成了异质结构. 以常见的有机污染物甲基橙、 亚甲基蓝和罗丹明B等为降解底物, 对Ag/ZnO纳米纤维的光催化性能进行了表征. 结果表明, 负载银纳米颗粒后, 复合催化剂的光催化性能明显提高.     

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.     

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.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.