动态配位空间的构筑与调控

“配位空间”(Coordination Space)是无机-有机杂化体系中的构筑基元通过配位键连接形成的具有特定结构和功能的空间。这一概念为基于配位键的框架体系的定向构筑与结构-性能调控提供了新的视角。作为典型的无机-有机杂化材料,金属-有机框架(Metal-Organic Framework,MOF)及金属有机笼(Metal-Organic Cage,MOC)等近年来受到广泛关注。这类材料的构筑与性能调控的核心可以认为是对其配位空间的结构设计与性能调控。具有刺激响应性的MOF可展现动态的配位空间,使其在吸附分离、传感、药物投递等方面具有重要的应用前景。本文将以动态金属有机框架的相关研究为基础简述动态配位空间研究的近期进展,包括其动态行为产生的结构基础、诱发因素及相关性能,归纳结构-性能的关系,为相关研究提供参考。     

多孔有机框架材料在真菌毒素分离富集与检测中的研究进展北大核心CSCD

真菌毒素是真菌产生的一类有毒的次级代谢产物,对人体具有致癌、致畸、致突变等严重危害,已引起世界范围的广泛关注。因此,建立准确、快速、灵敏的真菌毒素检测方法具有非常重要的意义。色谱法是常用的检测真菌毒素的方法,但由于真菌毒素种类繁多,分布范围广泛,样品基质复杂,且各类真菌毒素在实际样品中含量极低,难以对其进行直接分析。因此,发展适宜的样品前处理方法,并用于真菌毒素的高效分离富集是必不可少的步骤。近年来,以金属有机框架(MOF)、共价有机框架(COF)为代表的多孔有机框架材料因具有大的比表面积、高的孔隙率、可调的孔径、多样的框架结构、活性位点分布均匀、结构可修饰等优点被广泛应用于真菌毒素的样品前处理领域。同时,这些优点赋予MOF/COF材料以优异的荧光性质、电化学性质,使其在真菌毒素的分析传感等领域也得到了广泛关注。本文针对近年来MOF/COF材料在真菌毒素分离富集中常用的样品前处理方法(固相萃取、分散固相萃取、磁固相萃取、免疫磁珠分离)中的应用进行了综述。同时,针对MOF/COF材料在真菌毒素荧光传感、电化学传感中的研究进行了总结。最后,对存在的问题及未来的发展趋势进行了讨论与展望,为进一步探索MOF/COF材料在真菌毒素中的应用提供参考。     

二维金属有机框架纳米片的合成及在超电容和电催化领域的应用

二维金属有机框架(2D MOF)纳米片具有丰富且易暴露的表面活性位点、 高度有序的孔结构以及多样且可调的化学成分, 在电化学能量存储与转化中有利于降低反应电位, 提高扩散速率和反应速率. 关于2D MOF应用于电化学存储与转化的研究已有大量报道. 本文综合评述了近几年2D MOF的合成进展及其在超电容(SC)、 析氧反应(OER)、 析氢反应(HER)、 氧还原反应(ORR)和二氧化碳还原反应(CRR)的应用, 并对2D MOF作为电催化材料的研究现状和发展前景进行了总结与展望.     

水溶性三维有序超分子和共价有机聚合物

总结了近年来在水溶性三维超分子聚合物、 超分子有机框架、 超分子-金属有机框架杂化结构、 超分子-共价-金属有机框架杂化结构及共价有机框架合成、 催化和输送功能方面的研究进展, 指出了有序三维聚合物未来研究面临的挑战并展望今后的发展方向.     

金属-有机框架材料在液相催化化学制氢中的研究进展

金属-有机框架(MOFs)材料是由金属簇节点或金属离子与有机配体连接而成的典型的无机-有机杂合物, 作为一类新兴的无机多孔晶态材料, MOFs因具有高度有序的多孔性、 结构可裁剪性、 高比表面积及灵活多变的骨架类型等优点而在工业合成、 能源开发、 环境治理和生物制药等领域展现出广阔的应用前景. 本文从氢能源的开发利用出发, 总结了近年来MOFs基纳米复合材料在催化化学制氢方面的研究进展. 讨论了常见的含氢量高的化学储氢材料, 包括氨硼烷、 甲酸和水合肼等; 催化材料主要有单一MOFs、 MOF基贵金属和非贵金属复合材料及MOF基衍生材料等. 最后, 对MOF基复合材料在液相催化化学储氢中的应用前景进行了展望.     

金属有机框架基复合材料的制备及其光热性能研究

金属有机框架材料(metal-organic frameworks, MOFs)是一类新型的有机-无机杂化材料, 具有可功能化的骨架结构、高比表面积、可调控的孔径尺寸等优势. 将MOFs与性质多样的有机/无机功能纳米材料复合, 不仅有可能充分发挥组分各自的优势, 而且有可能产生“1+1>2”的协同效应, 因而引起了人们的广泛关注. 具有光热效应的MOF复合物作为一类重要的MOF复合材料, 在生物诊疗、催化等领域展现出了良好的应用前景. 作者首先综述了近年来MOF复合材料的主要可控制备方法, 随后讨论了光热MOF复合材料的应用研究, 最后对该类材料的未来研究方向和挑战进行了展望.     

用环糊精的金属有机框架材料作为模板制备多孔有机笼

迄今为止, 还未有报道过由金属有机框架材料(MOFs)转化成共价有机笼(COF-Cages)的文章. 通过交联环糊精MOF骨架中的羟基, 并除去其中的钾离子, 构建了由环糊精MOF转化形成的结晶性多孔有机笼. 首先合成CD-MOF, 再将CD-MOF中的羟基交联, 得到Cross-linked γ-环糊精MOF (CL-CD-MOF), 最后除去钾离子得到Z-cage, 并且应用热重分析(TGA)、红外光谱(IR)、固体核磁共振(CP/MAS/NMR)光谱等多种分析手段对其结构进行表征. 结果表明, 该方法得到的有机笼(Z-cage)具有特定的方钠石型晶体结构, 并且比表面积达862 m²·g^-1. 作为对照实验, 在水热条件下, 将γ-CD和对苯二硼酸按照1:4化学计量比合成的CL-polymer与Z-cage具有不同的晶体结构, 并通过X-射线粉末衍射(PXRD)进行了证明, 反映了MOF模板合成法在控制材料的晶体结构的优越性. 这种从结晶性无机-有机杂化MOF到结晶性有机笼Z-cage的转变, 提供了多孔晶体材料之间晶体到晶体转变的途径.     

共价有机框架材料催化剂

共价有机框架材料（covalent organic frameworks, COF）是功能材料领域研究的热点之一。COF具有孔道结构高度有序、孔径可调、比表面积较大、合成方法多样和易于功能化修饰等优点,是一类新兴的多相催化剂。目前,COF催化剂主要设计思路是：基于“自下而上”策略将非金属催化活性中心嵌入材料骨架来构筑本征型COF催化剂,或者以COF为载体,通过后修饰方式负载金属颗粒或离子构建多相催化剂。鉴于COF以上优势,预计COF催化剂在多相催化和手性催化领域中的应用也将取得更大的进展。本文综述了COF催化剂的合成和功能化策略,并展望了COF在多相催化领域中的应用前景。     

基于四硫富瓦烯的无金属共价有机框架材料用于高效电催化析氧反应

共价有机框架(COFs)在电催化析氧反应(OER)中的应用得到了广泛的关注。然而,大多数无金属共价有机框架(COFs)的导电性较差,不利于OER反应。四硫富瓦烯(TTF)是一种良好的电子供体,具有快速的电子转移能力,将TTF整合到共价有机框架骨架中将有助于电子的转移。在此,我们报道了一种基于四硫富瓦烯的二维无金属共价有机框架材料,JUC-630。与不含四硫富瓦烯的同类材料(Etta-Td COF)相比,JUC-630具有较低的过电位(400 mV)和塔菲尔斜率(104 mV∙dec⁻¹)。本研究提出了合理设计功能基元的策略,这有助于大大提高COF材料的OER催化活性。     

金属有机框架复合材料的合成及其在肿瘤诊疗领域中的应用

金属-有机框架(MOF)材料是指以有机配体为连接体和以金属离子簇为节点,通过配位键组装形成的具有周期性结构的配位化合物。该材料在气相传导、光学催化以及生物应用领域都有着应用潜力。不同形貌、大小和组分的MOF材料具有不同的物理化学性质。将金属纳米粒子和MOF材料的性能相结合,就能够有效地避免金属纳米粒子和MOF材料的相互凝聚。本文主要阐述了MOF材料的几种合成方法,包括气相法、液相法、固相法、模板法、微波法和电化学法,并对其优缺点进行了讨论。重点分析了其在肿瘤领域中的应用,包括药物负载、荧光标记和光动力学疗法等。最后指出今后其主要的研究方向是改善生物相容性、降低制备成本、扩展生物MOF及其负载药物的种类,使其应用到更多疾病的治疗上。     

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.     

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.     

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.     

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.     

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.     

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%).