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1.
溴代烷烃与活性氮的反应发光研究   总被引:1,自引:0,他引:1  
在流动余辉装置上, 利用N2空心阴极放电制备活性氮, 研究了活性氮与溴代烷烃(CHBr3、CH2Br2、C2H5Br、C4H9Br) 反应的化学发光.上述所有反应中, 在550~750 nm波段均观察到了较强的NBr (b1Σ+→X3Σ-)跃迁发射谱. 同时在活性氮与CHBr3和CH2Br2的反应中, 在流动管下游还观察到了CN (A2π, B2πX2Σ+)的发射谱. 验证性的实验表明, 激发态NBr (b1Σ+)是由二步过程形成: N(4S)与溴代烷烃反应生成NBr (X3Σ-), 再通过N2 (A 3Σu+)分子能量转移到激发态NBr (b1Σ+); 而激发态的CN是通过N(4S) + CBr→CN(A, B) + Br过程形成的.  相似文献   

2.
钙钛矿型LaxSr1-xNi1-yCoyO3光电催化活性研究   总被引:8,自引:0,他引:8  
用甘氨酸-硝酸盐燃烧合成法, 制备LaxSr1-xNi1-yCoyO3复合氧化物的陶瓷粉末, 对钙钛矿氧化物进行了XRD结构分析. 在通氧或不通氧下测试氧还原和氧析出的循环伏安曲线. 结果表明: 该氧电极具有双功能催化特性, 但不完全可逆. 利用汞灯作为激发光源, 进行几种水溶性染料和五种混合染料光解实验, 利用紫外-可见、红外以及人工神经网络光度法研究LaxSr1-xNi1-yCoyO3的催化性能. 结果表明: LaxSr1-xNi1-yCoyO3 (x=0.7, 0.9, 1; y=0.3, 0.75)复合氧化物都具有较强光催化特性; LaxSr1-xNi1-yCoyO3的光催化活性高于LaxSr1-xNiO3, 这与B位离子(Ni2—, Co2-)的电子构型有关; Co2+的加入可使LaxSr1-xNiO3的光催化活性有所提高.  相似文献   

3.
采用高温固相法在空气中合成了Ba1.97-yZn1-xMgxSi2O7:0.03Eu,yCe3+系列荧光粉。分别采用X-射线衍射和荧光光谱对所合成荧光粉的物相和发光性质进行了表征。在紫外光330~360 nm激发下,固溶体荧光粉Ba1.97-yZn1-xMgxSi2O7:0.03Eu的发射光谱在350~725 nm范围内呈现多谱峰发射,360和500 nm处有强的宽带发射属于Eu2+离子的4f65d1-4f7跃迁,590~725 nm红光区窄带谱源于Eu3+5D0-7FJ (J=1,2,3,4)跃迁,这表明,在空气气氛中,部分Eu3+在Ba1.97-yZn1-xMgxSi2O7基质中被还原成了Eu2+;当x=0.1时,荧光粉Ba1.97Zn0.9Mg0.1Si2O7:0.03Eu的绿色发光最强,表明Eu3+被还原成Eu2+离子的程度最大。当共掺入Ce3+离子后,形成Ba1.97-yZn0.9Mg0.1Si2O7:0.03Eu,yCe3+荧光粉体系,其发光随着Ce3+离子浓度的增大由蓝绿区经白光区到达橙红区;发现名义组成为Ba1.96Zn0.9Mg0.1Si2O7:0.01Ce3+,0.03Eu的荧光粉的色坐标为(0.323,0.311),接近理想白光,是一种有潜在应用价值的白光荧光粉。讨论了稀土离子在Ba2Zn0.9Mg0.1Si2O7基质中的能量传递与发光机理。  相似文献   

4.
The luminescent properties of Pr3+-doped LaB3O6, SrAl12O19, SrB4O7 and NaYF4 in the vaccum ultraviol-et (VUV) range at different temperatures were investigated under the excitation of high-energetic synchrotron radiation. For Pr3+ ions in LaB3O6, SrAl12O19 and SrB4O7, only the parity-forbidden 1S0→4f2 transitions were observ-ed in the emission spectra at relatively low temperature; but the parity-allowed 4f5d→4f2 transitions appeared simultaneously when the temperature was high enough. And the intensity of broad 4f5d→4f2 emission increased relative to the intensity of 1S0→4f2 emissions with increasing temperature. Then the thermal equilibrium model of energy levels was employed to the lowest 4f5d state and 1S0 state of Pr3+ in the three hosts. The calculated curves were in good agreement with the experimental values, indicating the occurrence of the thermal excitation from 1S0 state to 4f5d states at high temperatures when the lowest 4f5d state lies higher than 1S0 state and the photon energy is high enough.  相似文献   

5.
CeCl3-CdCl2-H2O和CeCl3-CdCl2-HCl-H2O的相平衡   总被引:5,自引:0,他引:5  
测定了三元系CeCl3-CdCl2-H2O (25 ℃)和四元系CeCl3-CdCl2-HCl(~8.4%)-H2O(25 ℃) 的相平衡溶度数据,绘制了相应的溶度图.该三元系是由5个固相区CdCl2&;#8226;2.5H2O(原始盐)、CdCl2&;#8226;H2O(原始盐)、6CdCl2&;#8226;CeCl3&;#8226;14H2O、4CdCl2&;#8226;CeCl3&;#8226;12H2O、CeCl3&;#8226;7H2O(原始盐)组成的复杂体系.该四元系是由5个固相区CdCl2&;#8226;H2O(原始盐)、9CdCl2&;#8226;CeCl3&;#8226;19H2O、6CdCl2&;#8226;CeCl3&;#8226;14H2O、4CdCl2&;#8226;CeCl3&;#8226;12H2O、CeCl3&;#8226;7H2O(原始盐)组成的复杂体系.其中6CdCl2&;#8226;CeCl3&;#8226;14H2O在该三元系是介稳化合物.9CdCl2&;#8226;CeCl3&;#8226;19H2O 、6CdCl2&;#8226;CeCl3&;#8226;14H2O和4CdCl2&;#8226;CeCl3&;#8226;12H2O用X射线粉末衍射及TG-DTG和DSC等方法进行了研究,并对X射线粉末衍射进行了指标化.  相似文献   

6.
采用简单沉积-沉淀法合成了Bi2WO6@Bi2MoO6-xF2x(BWO/BMO6-xF2x)异质结,借助XRD、XPS、TEM、SEM、EDS、UV-Vis-DRS、PC和EIS等测试技术对其组成、形貌、光吸收特性和光电化学性能等进行系统表征,并以模型污染物罗丹明B(RhB)的光催化降解作为探针反应来评价Bi2WO6@Bi2MoO6-xF2x异质结的光催化活性增强机制。形貌分析表明,所得Bi2MoO6微球由大量厚度为20~50 nm的纳米片组成;FE-SEM和HR-TEM分析表明,尺寸约为10 nm的Bi2WO6量子点均匀沉积在Bi2MoO6-xF2x微球表面,形成新颖的Bi2WO6@Bi2MoO6-xF2x异质结;与纯Bi2MoO6或者Bi2WO6相比,1∶1Bi2WO6@Bi2MoO6-xF2x异质结表现出更好的光催化活性和光电流性质,其对RhB光催化降解的表观速率常数分别为纯BMO和BWO的6.4和11.6倍。PC和EIS图谱分析表明,Bi2WO6量子点表面沉积显著提高Bi2MoO6-xF2x光生电子/空穴的分离效率和迁移速率;活性物种捕获实验证明了·O2-和h+是主要的活性物种。根据实验结果,探讨了F-掺杂和Bi2WO6量子点之间的协同效应对Bi2MoO6的光催化活性的影响机制。  相似文献   

7.
纳米钙钛矿LaxSr1-xFe1-yCoyO3复合氧化物的制备和表征   总被引:1,自引:0,他引:1  
用甘氨酸-硝酸盐燃烧合成法,制备LaxSr1-xFe1-yCoyO3复合氧化物的陶瓷粉末,对该钙钛矿型氧化物进行了XRD、IR、紫外漫反射光谱及循环伏安曲线分析。结果表明:该复合氧化物粉体平均晶粒为15.3~29.8 nm,为立方和正交晶系。该氧电极具有双功能催化特性,但不完全可逆。对水溶液染料进行光解实验,利用紫外-可见、人工神经网络光度法研究LaxSr1-xFe1-yCoyO3的催化性能。结果表明:CO2+的加入可使LaxSr1-xFeO3的光催化活性有所提高,B位离子(Fe3+,CO2+)改变与加入,使LaxSr1-xFe1-yCoyO3(x=0.7,0.3;y=0.3,0.9,1)光催化活性高于LaxSr1-xFeO3。同时,对5种染料进行紫外光解,在0.75 h,脱色率大于91%,并为动力学一级反应。  相似文献   

8.
新半金属Fe2LaO4磁电性能的第一性原理计算   总被引:1,自引:0,他引:1  
刘俊  陈希明  董会宁 《无机化学学报》2007,23(11):1857-1863
利用基于密度泛函理论的第一性原理赝势法设计并优化了含稀土元素的新半金属Fe2LaO4。详细计算了其电荷分布,分子磁矩等磁电性能,并结合配位场理论分析了其电子结构。结果表明,Fe2LaO4是一种含稀土元素的铁磁性的新ⅡB型半金属;它的稳定相晶格常数约为0.623 nm,分子磁矩约为1.0μB;Fe2LaO4属软铁磁性半金属;La较多的外层电子增强了Fe2LaO4内部的库仑斥力,导致了配合物ML4和ML6均受强场作用,从而使Fe2LaO4具有软铁磁性;考虑自旋分布后ML4和ML6的电子结构分别为a1g1a1g1t1u3t1u3eg2eg2t2g3t2g3↓和a1g1a1g1t1u3t1u3t2g3t2g3eg2eg2eg*1↑,这些电子属于分子轨道。  相似文献   

9.
用传统湿式浸渍法制备了La2O3掺杂的商业γ-Al2O3负载的沼气重整催化剂Ni-Co/La2O3-γ-Al2O3, 并用程序升温加氢(TPH)、程序升温氧化(TPO)、程序升温表面反应(TPSR)、程序升温脱附(TPD)及脉冲实验对催化剂进行了表征. 结果表明, 沼气重整过程中Ni-Co/La2O3-γ-Al2O3催化剂上的表面碳物种主要来源于CH4的裂解, CO2的贡献很小. CH4裂解能够产生三种活性不同的碳物种, 即Cα、Cβ与Cγ. 随着反应的进行, Cα物种减小而Cβ与Cγ物种增加, 且Cγ物种能够转变为惰性的石墨碳. 重整反应过程中CH4与CO2的活化能相互促进. 催化剂表面的O物种与C反应生成CO或与CHx反应生成CHxO再分解为CO与吸附态的H物种, 可能是Ni-Co/La2O3-γ-Al2O3催化剂上沼气重整的速率控制步骤.  相似文献   

10.
本文采用离子交换法分别制备了双复合锂锰氧化物Li0.60[MgxMn1-x]O2(0.05 ≤ x ≤ 0.15)和三复合锂锰氧化物Li0.60[MgxCoyMn1-x-y]O2(x=0.05,0.05 ≤   相似文献   

11.
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.  相似文献   

12.
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.  相似文献   

13.
The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.  相似文献   

14.
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.  相似文献   

15.
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.  相似文献   

16.
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.  相似文献   

17.
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.  相似文献   

18.
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.  相似文献   

19.
20.
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%).  相似文献   

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