共沉淀法合成的（Y，Gd）BxV1-xO4-x：Eu荧光粉的光谱特性研究

采用共沉淀反应软化学法合成了体色洁白的（Y，Gd）BxV1-xO4-x：Eu^3＋荧光粉。在147nm真空紫外线的激发下，（Y，Gd）BxV1-xO4-x：Eu^3＋荧光粉的发射主峰位于619nm，红色色纯度优于PDP用商品（Y，Gd）BxV1-xO4-x：Eu^3＋荧光粉，但其相对发光亮度只有商品粉的90％，是一种有前途的PDP用和荧光灯用的红色荧光粉。     

稀土荧光粉预制品制备新工艺

分析了高温固相合成生产稀土荧光粉和湿法共沉淀预制备法生产稀土荧光粉的特点,表明通过湿法共沉淀可以在较短时间和较低温度下合成稀土荧光粉, 介绍了Y2O3∶ Eu, LaPO4∶ Ce, Tb和SrAl2O4∶ Eu2+的湿法共沉淀预制备的方法.     

(Y,Gd)VO_4∶Eu~(3+)的紫外-真空紫外发光特性

用高温固相法合成了Y1-xGdxVO4∶Eu3 (0≤x≤1)系列单相样品并研究了其发光特性。在254nm激发下,观察到最大强度位于619nm的红色发射峰且其强度在Y/Gd=0.4/0.6时达到最大。在147nm激发下的发射峰与紫外下的一致,发射强度也是在Y/Gd=0.4/0.6时达到最大,大约是商用(Y,Gd)BO3∶Eu3 荧光体的65%。619nm监控下的真空紫外激发光谱由峰值位于158nm,204nm,247nm以及300nm的系列激发带组成,归属于钒酸根的基质吸收以及Gd3 、Y3 和Eu3 的电荷迁移带吸收。相对(Y,Gd)BO3∶Eu3 中Eu3 占据中心对称格位,(Y,Gd)VO4∶Eu3 中Eu3 占据非中心对称格位,其真空紫外下光谱色纯度更好。色坐标分别为(0.632,0.355),(0.672,0.328)。     

Ga2S3：Eu^2＋和SrGa^2＋xS4＋y：Eu^2＋系列荧光粉的发光性能研究

采用高温固相法合成了Ga2S3：Eu^2 和SrGa2S4：Eu^2 系列荧光粉。发现Ga2S3：Eu^2 的发射峰位于570nm附近，SrGa2S4：Eu^2 的发射峰位于535nm附近。同时进一步探讨了SrGa2 xS4 y：Eu^2 体系中，过量的Ga对发光的影响，通过漫反射光谱和XRD谱确定过量的Ga是以Ga2S3的形式存在于SrGa2S4相中；通过荧光光谱发现过量的Ga并不引起SrGa2S4：Eu^2 发射峰的位移，而是增强其在400-520nm处激发峰的强度，从而增强Eu^2 在535nm处的发光强度。     

Sr1-xZnxY2S4∶Er^3＋,Eu^2＋荧光粉的合成与发光特性的研究

采用碳酸盐前躯体高温分解法合成了Sr1-xZnxY2S4∶Er^3＋,Sr1-xZnxY2S4∶Eu^2＋和Sr1-xZnxY2S4∶Er^3＋,Eu^2＋红色荧光粉。XRD图谱表明,Zn^2＋掺杂量x〈0.2 mol时,粉末样品为CaFe2O4型正交晶体。Zn^2＋离子在Sr1-xZnxY2S4∶Er^3＋,Eu^2＋中的固溶量（xmol）对荧光粉的发射强度影响很大。随着Zn^2＋离子掺杂浓度的增加,Sr1-xZnxY2S4∶Er^3＋,Eu^2＋（SZYSEE）紫外区激发峰（200-413 nm）发生红移,并与可见光激发带（413-600 nm）形成一个连续的宽带谱,与紫外和GaN基LED芯片辐射都有良好的匹配性。当Zn^2＋掺杂量为0.1 mol时,SZYSEE的发光强度达到最大,其发光强度比未掺Zn2＋的增强10.7倍。Sr0.9Zn0.1Y1.76S4∶0.24Er^3＋,0.006Eu^2＋是一种潜在的白光LED用红色荧光粉。     

若干物理处理方法对稀土荧光粉Y2O3:Eu3+发光性能的影响

采用物理法对商品化稀土荧光粉Y2O3：Eu^3＋进行改性，考察了真空干燥温度、焙烧温度对其发光性能的影响。SEM和TEM观测结果表明，经过200℃真空干燥后，随着焙烧温度的增加，荧光粉的分散性得到改善，且以纳米颗粒为主（5～85nm）。XRD测量结果表明，随着焙烧温度的增加，Y203：Eu^3＋的结晶度逐渐增加。发射光谱测试结果表明，真空干燥温度为200℃，焙烧温度为1200℃时得到的样品的发光性能较好。     

M2B5O9X：Eu，Tb（M=Ca,Sr;X=Cl,Br）荧光体的光谱特征

利用Eu^3 和Tb^3 稀土离子之间存在电子组态共轭性的特征,将其双掺于同一基质中,由于电子转移而产生Eu^2 ,使Eu^3 ,Tb^3 和Eu^2 共存于同一体系中,在空气中合成了M2B5O9X：Eu,Tb荧光粉,研究了其发光特征及影响作用。结果表明,Eu^3 ,Tb^3 和Eu^2 共存于同一基质中,且稀土离子的掺杂量对其光谱产生影响。     

Eu3+在SrZnP2O7中的发光性能和Eu3+, Bi3+间的能量传递

采用高温固相法合成了SrZnP2O7：Eu^3＋荧光粉,该荧光粉的激发主峰值位于400nm,适用于UVLED管芯的激发;在紫外激发下的发射峰由位于591和597nm（^5D0～^7F1）,616,624和629nm（^5D0～^7F2）,656nm（^5D0～^7F3）及688nm（^5D0～^7F4）4组线状峰构成,对应Eu^3＋的特征跃迁,呈现橙红色发光。分析了Eu^3＋离子浓度对样品发光效率的影响,随着浓度增加,其发射一直增强,但其发光效率已经开始减弱。Bi^3＋的加入使发光强度得到很大提高,并讨论了在SrZnP2O7基质中Bi^3＋对Eu^3＋的能量传递和敏化作用。     

白光LED用红色发射荧光粉Gd2(MoO4)3:Eu3+制备与表征

以NH4F为助熔剂采用固相反应法合成了Eu^3＋掺杂的α—Gd2（MoO4）3荧光粉。研究了引入不同含量助熔剂时对材料的结晶、荧光粉颗粒粒径、表面形貌及光谱性质的影响。实验结果表明,引入重量比为3％时样品具有好的结晶和优良的光谱性质;同时,随着助熔剂量的增加Eu^3＋离子在晶体中所处的格位对称性发生了变化;另外,通过Eu^3＋掺杂浓度变化的结果讨论了Eu^3＋的浓度猝灭行为。光谱测量的结果表明,该荧光粉与其他商品荧光粉不同,其最有效的激发波长不在电荷迁移带范围,而是465和395nm跃迁,该荧光粉可作为近紫外LED和三基色荧光粉组合型自光器件的红色荧光粉的候选材料。     

镨和镱掺杂Ba2SiO4∶Eu^2＋荧光材料的合成与发光性能

采用高温固相反应法分别合成了变价稀土镨和镱离子掺杂的绿色荧光粉[Ba（2-n-1.5x）REx]SiO4∶nEu^2＋（n=0.03,RE=Pr,Yb;x=0,0.02,0.05,0.10）。结果表明：所有合成荧光粉的激发峰均为250-400 nm的宽峰,与近紫外LED的发射光波长相匹配。发射峰位于450-550 nm之间,是Eu2＋的5d-4f跃迁的典型发射。Pr^3＋和Yb3＋的掺入并未改变Ba2SiO4∶Eu^2＋的相组成,但对荧光强度的影响大,且与掺杂元素、掺杂量和煅烧温度相关。当掺杂Pr^3＋和Yb3＋的量为x=0.02时,经1150℃煅烧所得荧光粉的发光强度分别是未掺杂时的595%和168%。证明三价稀土离子掺杂可以导致基质中的电荷缺陷而敏化Eu^2＋离子的发光,而变价稀土离子的掺杂可以大大提高电荷缺陷,导致荧光强度的进一步提高。     

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%.     

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.     

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.     

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.     

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.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

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.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

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.