铅卤钙钛矿-聚合物复合材料的制备及应用

铅卤钙钛矿纳米晶具有优异的光电性能,在太阳能电池、光电探测和生物成像等领域展现出巨大的发展潜力。然而,铅卤钙钛矿纳米晶自身稳定性差的缺陷制约了其在实际生活中的应用。将铅卤钙钛矿纳米晶嵌入到聚合物中以制备钙钛矿-聚合物复合材料是近年来发展起来的一种有效增强钙钛矿稳定性的策略,特别是致密的聚合物基质赋予钙钛矿纳米晶优异的水稳定性。本文综述了近十年钙钛矿-聚合物复合材料的制备方法及在发光器件和生物医药等领域的应用,探讨了目前仍存在的一些问题和解决方法,并对未来这一领域的发展进行了展望。     

激光作用铅卤钙钛矿的机理与应用

近年来,铅卤钙钛矿纳米晶因其易制备,低成本,高性能等特性引起了人们极大的关注。钙钛矿纳米晶的光电性能优越应用潜力巨大,然而稳定性问题制约着它进一步发展,使其无法与已经商业化的应用相匹敌。针对钙钛矿材料的稳定性问题,人们展开了很多研究,其中一个方面就是光照稳定性。该方面的研究可以为制备高稳定性钙钛矿材料和器件奠定基础,还可以利用光照(特别是激光)来调控钙钛矿的结构和性能,拓展其在光电领域的全方位应用。本文专注于激光照射下钙钛矿的变化及其相关应用,首先综述了激光辐照铅卤钙钛矿时出现的变化现象以及微观机理;其次,基于这些变化机理,介绍了最近研究人员如何使用激光技术对钙钛矿薄膜和器件进行性能调控,以及激光直写钙钛矿技术的相关应用。     

无机铅卤钙钛矿纳米晶的合成、性能及应用

无机铅卤钙钛矿CsPbX₃(X=Cl,Br,I)纳米晶因具有较高荧光量子效率(~90%)、发光波长覆盖整个可见光谱(400~700 nm)、半高宽相对较窄(12~42 nm)等诸多优点而备受关注,这些性能使之成为当前最具有潜在应用价值的发光材料之一。 因此,近年来对该类无机铅卤钙钛矿材料的报道越来越多。 本文主要介绍了无机铅卤钙钛矿发光材料的发展历程、结构、制备方法、生长机理及当前的主要应用领域等,最后概括了无机铅卤钙钛矿发光材料在当前研究背景下所面临的问题并展望了下一阶段的发展方向,为进一步提高其光学性能及开发新型高效的无机铅卤钙钛矿发光材料奠定基础。     

无铅卤系钙钛矿纳米晶:新一代光催化材料

由于TiO₂光催化材料具有反应速度快、稳定性好、不产生二次污染等优点,常被应用于污染物降解、CO₂还原、制氢等领域,然而TiO₂可见光利用率低,限制了其进一步广泛应用。近年来,无铅卤系钙钛矿纳米晶由于其带隙可调、可见光吸收能力强等优势在光催化领域显示出巨大的潜力。相关研究表明:无铅卤系钙钛矿纳米晶可成功应用于CO₂还原、有机污染物降解等领域,效果显著。基于此,本文首先阐述了无铅卤系钙钛矿纳米晶的制备方法,并系统地总结了其在CO₂还原、制氢、污染物降解、NO去除等领域的应用研究进展,最后就现阶段无铅卤系钙钛矿纳米晶光催化材料研究中存在的问题及今后的研究方向进行了分析和展望。     

CsPbX3(X=Cl,Br,I)纳米晶的制备及其应用

全无机钙钛矿CsPbX₃(X = Cl, Br, I) 纳米晶作为一类新型的低成本直接带隙半导体材料,具有优异的光学性质,如吸收系数高、尺寸和发射波长易调节、半峰宽窄、荧光量子产率高等特性,在照明、能源、信息显示和探测等领域表现出巨大的应用潜力,成为材料领域的研究热点。本文从CsPbX₃纳米晶的结构组成入手,重点综述了其常见的制备方法如高温热注入法、室温再沉淀法、溶剂热法、液滴微流控法、阴离子交换法等,对常见的形貌尺寸控制策略如反应温度和表面配体进行归纳,以及改善CsPbX₃纳米晶稳定性的策略,总结了此类材料在白色发光二极管、电致发光二极管、激光器、光电探测器、太阳能电池等光电领域的应用情况,最后对CsPbX₃纳米晶领域存在的问题和面临的挑战进行了分析和评述。     

钙钛矿材料组分调控策略及其光电器件性能研究进展

近年来，钙钛矿太阳电池的光电转换效率取得了爆发式增长，这与电池中钙钛矿薄膜的制备工艺和材料组分密切相关.关于钙钛矿薄膜的制备方法，相关的研究报道及综述较多，然而钙钛矿材料组分调控方面的研究梳理工作相对缺乏.本综述总结了近年来不同组分体系钙钛矿材料的研究进展，包括有机无机铅卤钙钛矿、全无机铅卤钙钛矿、少铅钙钛矿以及无铅钙钛矿.重点介绍了不同体系中具有代表性的材料组分及其对器件性能的影响，旨在梳理通过组分调控提高钙钛矿电池的效率及稳定性的研究思路，最终实现商业化应用.     

金属离子掺杂全无机铅卤钙钛矿CsPbX_3纳米晶

无机铅卤钙钛矿CsPbX_3(X=Cl、Br、I或混合卤素)半导体纳米晶具有优异的光学和光电特性,是构筑照明、显示、光探测和光伏等多种光电器件颇有潜力的核心材料.这类材料在应用中存在的主要问题是如何协同调控或改善性能、提升稳定性并降低有毒铅的量. Pb~(2+)所在格位在决定其电子结构乃至光学和光电性能方面起着重要的作用.因此,最理想的方法是在Pb~(2+)的格位上有效且可控掺杂合适的金属离子.近年来,许多工作报道了CsPbX_3纳米晶的金属离子掺杂特性研究.为了更好地了解掺杂机制,未来开发出性能更优异的掺杂型钙钛矿材料,本文从掺杂离子、驱动力、掺杂策略及掺杂机理4个方面,分别总结了掺杂金属离子的种类及对光学和光电性能的影响,分析了掺杂剂中的阴离子和驱动力的作用,概述了主要的掺杂策略,系统阐述了后合成掺杂机理的核心思想,并指出了它们的不足之处,最后展望了今后在有效可控掺杂研究方面的一些挑战.     

一种钙钛矿纳米晶核壳结构的制备及其在重金属离子检测中的应用

采用3种配体合成一种壳层很薄且无法将纳米晶完全包覆的钙钛矿纳米晶核壳结构,并通过X射线衍射（XRD）和透射电子显微镜（TEM）表征证明此不完全包覆的纳米晶核壳结构成功制备。相比于原始钙钛矿纳米晶,该钙钛矿量子点核壳结构具有较好的稳定性,可与相关金属离子接触发生电子转移,使量子点的荧光发生猝灭,达到检测重金属离子的目的。所制备的钙钛矿纳米晶核壳结构可灵敏地检测铜离子和汞离子,理论检出限分别为0.60 nmol/L和0.64 nmol/L。该研究对开发新型量子点荧光检测剂具有重要意义。     

如何提升铅卤钙钛矿量子点的稳定性?

钙钛矿量子点因其优越的光电性能(如可调节的发光、窄的发光谱线、高的量子效率以及方便制备等)成为半导体发光领域的研究热点之一.虽然钙钛矿量子点在发光二极管方面具有良好的应用前景,但要想实现其商业化,仍然面临着很多问题.首先是稳定性较差,钙钛矿量子点在光、热、空气中会发生不可逆转的降解,进而导致严重的荧光猝灭,这一缺点严重地阻碍了其在实际中的应用.铅卤钙钛矿较差的稳定性也受到了研究者的广泛关注,近年来,许多工作报道了提升钙钛矿量子点稳定性的有效方法.本文详细分析了铅卤钙钛矿量子点不稳定性的来源,包括钙钛矿结构的不稳定性以及环境应力诱导下的降解,总结了近年来关于提升钙钛矿量子点稳定性的基本方法,并提出了改善铅卤钙钛矿量子点稳定性的一些建议.     

环境友好型无铅卤化物钙钛矿太阳能电池研究进展

ABX_3(A为甲胺、甲脒等有机离子或铯离子,B为铅或锡等金属离子,X为溴、碘等卤化物离子)卤化物钙钛矿材料具有优异的光电特性,是当前太阳能电池研究的前沿和热点之一。然而,这类太阳能电池普遍面临含毒性元素铅和稳定性差等问题,极大地阻碍了钙钛矿太阳能电池商业化应用进程。因此,发展新型高效无铅钙钛矿太阳能电池势在必行。本文评述了环境友好型无铅卤化物钙钛矿太阳能电池的最新研究动态和进展,探讨了该类太阳能电池的制备、性能及其稳定性等问题,展望了其未来发展趋势。     

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%.     

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.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

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.     

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.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

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.