稀土红色长余辉发光材料研究进展

综述了稀土元素掺杂红色长余辉发光材料的研究进展，总结了硫化物、钛酸盐、硫氧化物、硅酸盐、氧化物和磷酸盐等基质体系的红色长余辉发光，并指出硫氧化物和磷酸盐等基质是最具有发展前景的红色长余辉发光体系，讨论了Eu^2 在硫化物、Pr^3 在钛酸盐以及Eu^3 和Sm^3 等稀土离子在硫氧化物和硅酸盐等体系中的红色长余辉发光机制。介绍了传统的高温固相法以及溶胶．凝胶法、微波合成法等稀土红色长余辉材料的制备技术。提出了从基质材料、制备技术和稀土离子发光机制入手是稀土红色长余辉发光材料今后研究与开发的发展方向。     

长余辉发光玻璃SrAl2O4∶Dy, Eu的制备与发光性能研究

在低熔点破璃中掺杂一定量的长余辉发光粉制备了性能优良的长余辉发光玻璃。在保证发光玻璃均匀透明的基础上，发光性能随发光粉掺杂量的增加而增强，尽量降低假烧温度和减少保温时间可以保持良好的发光性能，在还原气氛制备的发光玻璃性能优于在空气中制备的。煅烧工艺对发光玻璃的微观结构有显著的影响。     

激活CaO-MgO-SiO_2长余辉玻璃发光性质

报道了一种新型的Eu~(2+)离子激活硅酸盐玻璃,该玻璃组成为2CaO-MgO-3SiO_2-0.015Eu_2O_3(CMSE)。通过透射光谱、稳态荧光光谱、余辉光谱和热释光等技术手段对CMSE的发光性质进行了深入研究。研究发现CMSE可以被紫光和近紫外光激发,获得黄色长余辉发光。热释光曲线的分析表明,CMSE的长余辉性质主要来自于玻璃基质中陷阱深度为0.83 e V左右的定域能级。研究认为对CMSE发光性质的研究有利于开发新型稀土离子激活近紫外激发LED用硅酸盐玻璃发光材料。     

长余辉发光材料在陶瓷行业的应用研究

长余辉发光材料和陶／搪瓷材料的结合始于80年代,当时采用的是传统的硫化物体系长余辉发光材料。20世纪90年代,随着多种新型长余辉材料的发现,使性能更佳的长余辉陶／搪瓷制品的开发成为可能。本文介绍新型铝酸盐体系、硅酸盐体系及新型红色长余辉材料应用于低温陶／搪瓷釉料（800－900℃）、中温陶瓷釉料（980－1100℃）,及将低温陶／搪瓷釉料、中温陶瓷釉料应用于陶／搪瓷制品的研究,以及将各种新型长余辉材料应用于花纸、玻璃行业中。这种长余辉陶／瓷制品性能稳定、发光强度达到发光粉的80％,发光时间可达12h以上;而且应用工艺简单,可直接用传统的陶／搪瓷制品工艺进行生产。     

ZnO-B2O3∶Tb3+长余辉玻璃的发光性质

通过还原方法制备了Tb³⁺离子掺杂的硼酸锌玻璃，并观察到在254 nm紫外光激发后有明亮的绿色长余辉发光现象，余辉时间达6 h。通过激发与发射光谱、余辉光谱、余辉衰减曲线、热释光谱、热释光释出速率衰减曲线等得到的信息，研究了Tb³⁺离子掺杂的硼酸锌玻璃的发光性质。     

蓝紫色ZnO-Al2O3-SiO2长余辉陶瓷

通过高温固相法首次合成并报道了兰紫色ZnO-Al2O3-SiO2长余辉陶瓷，系统地研究了其发光和缺陷性质，在强度0.6mW.cm^-2，主峰254nm的UVP紫外灯下激发15min，然后关闭激发源，样品发射兰紫色长余辉，撤去激发源以后5s，余辉初始强度为230mcd.m^-1，色坐标为（0．1292，0．0984），暗视场中，8h以后余辉仍然肉眼可辨，样品的紫外可见发射和不同时间的余辉发射光谱显示，荧光发射位于390nm，来源于基质的自致发光，而余辉有两个发射峰，主峰位于390nm，肩峰位于520nm，这表明样品中存在两种余辉发射中心，由余辉衰减曲线可以看出，这两种余辉发光都由一个快过程和一个慢过程组成，其中，慢过程决定了材料的长余辉时间，从时间依赖的余辉强度倒数曲线可以看出，余辉强度与时间成反比，这表明余辉发光的机理为电子空穴复合过程，热释光谱显示，样品分别在92和250℃附近出现两个宽的热释峰，说明材料中至少存在两种具有不同陷阱深度的电子或空穴缺陷中心。     

长余辉发光材料研究进展

90年代发现和发展起来的铝酸盐体系长余辉发光材料是一类重要的新 型能源材料和节能材料。本文主要综述了最近几年来铝酸盐体系中长人科辉发光研究进展。指出了氧化物体系长余辉发光材料的特点和优势,总结了新型长余辉发光材料的基质和激活剂种类、性质及其对稀土 离子 长余辉发光性能的影响和作用,概括了长余辉发光模型,并提出了今后研究和应用的发展方向。     

ZnO-B2O3∶Tb3+长余辉玻璃的发光性质

通过还原方法制备了Tb3+离子掺杂的硼酸锌玻璃,并观察到在254 nm紫外光激发后有明亮的绿色长余辉发光现象,余辉时间达6 h.通过激发与发射光谱、余辉光谱、余辉衰减曲线、热释光谱、热释光释出速率衰减曲线等得到的信息,研究了Tb3+离子掺杂的硼酸锌玻璃的发光性质.     

稀土超长余辉材料及其涂料的研究

以碳酸锶、氧化铝、氧化铕和氧化镝为原料，用高温固相反应法合成了稀土超长余辉发光材料SrAl2O4：Eu^2 ,Dy^3 。测试了该发光材料的激发光谱、发射光谱、余辉亮度及余辉时间，激发光谱主峰分别位于320和360nm处，激发波长的范围较宽，从紫外到可见光区均可激发该发光材料。发射光谱的主峰位于520nm，发光颜色为黄绿色，余辉可达16h以上。解释了超长余辉发光材料的发光机制。以苯丙乳液为成膜物，添加适量的发光粉及适当的助剂研制出一种超长余辉发光涂料。确定出了该涂料的最佳配方，测定了涂料的各种性能，并对影响涂料性能的主要因素进行了探讨。     

红色发光长余辉材料Ca2SnO4:Eu3+的性能研究

利用高温固相法合成了Ca2nO4:Eu3+色发射长余辉发光材料,对样品进行了X射线衍射分析、荧光光谱分析、形貌分析以及发光寿命测量.分析结果表明,在1350℃下烧结3 h的Ca2SnO4:Eu3+为单相产物,所得Ca2SnO4:Eu3+发光材料具有良好的发光性能,在267 nm紫外线激发下发出最强发射位于617 nm的锐线发射,并且具有明显的长余辉发光性能.     

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.     

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.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.     

Catalyst free,visible-light promoted photoaddition reactions between C60 and N-trimethylsilylmethyl-substituted tertiary amines for synthesis of aminomethyl-1,2-dihydrofullerenes

An efficient and benign method for the preparation of aminomethyl-substituted fullerenes has been developed. The process, involving catalyst free, visible-light irradiation of 10% EtOH-toluene solutions containing fullerene C₆₀ and N-trimethylsilylmethyl-substituted amines by using a 20 W compact fluorescent lamp, leads to formation of aminomethyl-substituted fullerene adducts in a highly efficient manner. The photoaddition reaction takes place via a pathway initiated by visible light absorption by C₆₀, followed by SET from the amine to the triplet excited state of C₆₀. Ethanol-promoted desilylation of the resulting a minimum radical then generates the corresponding α-amino radical which couples with the C₆₀ radical anion to form the anion precursor of the fullerene adducts. The new approach using visible-light takes place under mild conditions and it does not require the use of photocatalysts. Thus, the method developed in this effort could broadens the range of functionalized fullerene derivatives that can be readily prepared.     

Highly efficient and stereoselective cycloaddition of nitrones to indolyl- and pyrrolylacrylates

The reactions of various nitrones with indolyl- and pyrrolylacrylates proceeds regioselectively with high diastereoselectivity in the case of aldonitrones, and represents an effective method for obtaining new indolyl- and pyrrolyl-substituted isoxazolidine carboxylates stabilized by weak (CH?O) and moderate (NH?N) strength intramolecular hydrogen bonding. The resulting cycloadducts exhibit promising in vitro anti-influenza activities.     

Transition metal-free direct amination of benzoxazoles using formamides as nitrogen sources

A transition metal-free method for the direct amination of benzoxazoles using formamides as nitrogen sources is reported, which was mediated by an inexpensive and environmentally friendly tetrabutylammonium iodide/tert-butyl hydroperoxide system and gave the 2-aminobenzoxazole derivatives with moderate to good yields.     

l-Proline-catalyzed five-component domino reaction leading to multifunctionalized 1,2,3,4-tetrahydropyridines

Multifunctionalized 1,2,3,4-tetrahydropyridines are concisely synthesized in good yields via l-proline-catalyzed or l-proline/FeCl₃-cocatalyzed one-pot multicomponent reactions (MCRs). The MCRs involve a domino hydroamination/prins reaction/Mannich-type reaction/intramolecular dehydration-cyclization process. The molecular structure of 5baa, one of multifunctionalized 1,2,3,4-tetrahydropyridines, was confirmed by single-crystal X-ray diffraction.     

Exploring the scope of the Gewald reaction: Expansion to a four-component process

An efficient four-component reaction was developed to take advantage of the reactivity of the 2-aminothiophene-3-carbonitrile functionality, which is obtained during the classical three-component Gewald reaction. Various α-methylene bearing ketones were reacted with malononitrile, elemental sulfur, and aryl/heteroarylnitrile derivatives in t-BuOH/NaOH to afford 2-arylthieno[2,3-d]pyrimidin-4-amines in high yields. Preliminary studies revealed the photophysical properties of the products and their potential for use as metal sensors.