α-氨基酸各官能团对其Co(Ⅱ)配合物可逆氧合性能的影响

选择氧合性能良好的组氨酸(His)-Co(Ⅱ)作为研究对象, 分别掩蔽—NH₂、 取代—O^-和去除—COO^-, 得到短肽、 伪肽和多胺等类组氨酸结构. 采用UV-Vis光谱法研究了α-氨基酸中的3个官能团对其Co(Ⅱ)配合物氧合性能的影响. 对比研究表明: α-氨基酸中—NH₂对其Co(Ⅱ)配合物的吸氧性具有决定作用; —COO^-对其Co(Ⅱ)配合物氧合作用的可逆性起关键作用; 而—O^-对其Co(Ⅱ)配合物的吸氧性影响不大. 在前期研究结果的基础上, 对α-氨基酸-Co(Ⅱ)配合物可逆吸收和释放O₂的机理进行了探讨.     

N^C^N型Pt(II)配合物与大环主体葫芦[10]脲的识别及发光性质研究

由于过渡金属配合物具有独特的光物理化学性质而被广泛研究. 其中Pt(Ⅱ)配合物发生组装时会因Pt(Ⅱ)-Pt(Ⅱ)之间的距离不同而显示不同的荧光特性, 而主客体相互作用可以影响发光小分子的排列及组装. 为进一步探究主客体相互作用对Pt(Ⅱ)配合物发光性能的影响, 设计合成了不同取代的N^C^N型Pt(Ⅱ)配合物, 研究了大环主体葫芦[10]脲(CB[10])对这类配合物的识别作用及包合物的光谱性质. 核磁共振氢谱和质谱证明CB[10]可与配合物以1∶2的比例结合. 紫外-可见吸收光谱和荧光发射光谱分析表明主客体作用对该类金属配合物光谱性质有较大影响, 所形成的主客体包合物的磷光寿命及量子产率都有不同程度的变化. 研究结果表明, CB[10]可通过包结两个Pt(Ⅱ)配合物分子, 拉近铂原子之间的距离, 增强该类配合物在水相中的Pt(II)…Pt(II)相互作用和π-π相互作用, 实现水相中的长寿命磷光发射. 同时, 主客体作用对这类金属配合物的力致变色性质也有一定的影响.     

低相对分子质量有机酸对α-FeO(OH)吸附As(Ⅲ)的影响

制备并表征了α-FeO(OH),探究了4种低相对分子质量有机酸(LMW)对α-FeO(OH)吸附As(Ⅲ)的影响,并阐明了机理。 单一和混合LMW对α-FeO(OH)吸附As(Ⅲ)均有抑制作用,4种LMW的影响大小顺序为:草酸(OA)>柠檬酸(CA)>乳酸(LA)、水杨酸(SA)。 混合LMW的影响为:OA会加剧CA对α-FeO(OH)吸附As(Ⅲ)的影响,而SA几乎不起作用。 当ρ(As(Ⅲ))较低,LMW通过与α-FeO(OH)的静电引力、与α-FeO(OH)表面的铁离子形成配合物、生成沉淀从而影响α-FeO(OH)对As(Ⅲ)的吸附;当ρ(As(Ⅲ))较高,LMW还通过阻碍As(Ⅲ)在α-FeO(OH)上的扩散和沉淀作用产生影响。 实验结果为土壤中As(Ⅲ)的迁移转化、污染治理提供技术支撑。     

钴(Ⅱ)-氨基酸配合物催化性能与氧合性能的关系

研究了13种钴(Ⅱ)-氨基酸配合物的可逆氧合性能和催化性能之间的关系, 通过配合物活化分子氧(O₂)氧化环己烯考察其催化性能. 结果表明, 13种钴(Ⅱ)-氨基酸配合物均具有不同程度的可逆氧合性能和催化活性. 配合物完成一个可逆吸氧周期的用时越短, 其可逆氧合性能越好, 催化性能越差; 相反, 吸氧周期长及可逆氧合性能差的配合物其催化性能却更好. 另外, 在对配合物不同配比的研究中发现, Co(Ⅱ)与氨基酸的摩尔比为1:3(或1:2)饱和配位时, 可逆吸氧性能较好, 但其催化性能较差, 环己烯转化率较低; 在1:1型配位不饱和时, 吸氧的可逆性较差, 但催化性能优良, 环己烯的转化率可达82.5%. 结合结构分析和理论计算的结果可知, 不同钴(Ⅱ)-氨基酸配合物的氧合可逆性和催化性能的差异, 主要归因于氨基酸配体的残基与Co(Ⅱ)的结合能力的不同. 氨基酸配体的残基与Co(Ⅱ)的结合能力越好, 越有利于配合物由高自旋态向低自旋态转化, 并与O₂可逆结合, 不利于烯烃基的取代, 配合物表现出较差的催化性能, 反之亦然.     

自负载吡啶双亚胺酸酯钒(Ⅲ)催化剂的合成及催化乙烯聚合

合成了一系列自负载吡啶双亚胺酸酯钒(Ⅲ)催化剂(V(Ⅲ)),并通过傅里叶变换红外光谱仪(FTIR)、元素分析及核磁共振波谱仪(NMR)等技术手段对配合物进行了表征。 在倍半乙基氯化铝(EASC)活化下,V(Ⅲ)催化剂对乙烯聚合表现出很高的催化活性(7.2~12.1 g/(mol·h·Pa)),且自负载基团的链长对催化剂的活性及所得聚合物的性质影响较小。 同时,该类V催化剂催化乙烯与1-己烯共聚合性能良好,得到高相对分子质量(高达68.1×10³)的聚合物。 所得聚合物经扫描电子显微镜(SEM)表征,其微观结构为片层叠加结构。     

双二苷酰胺从硝酸溶液中萃取Eu(Ⅲ)和Am(Ⅲ)

采用混合酸酐法合成了两种双二苷酰胺(bisdiglycolamide, BisDGA)萃取剂: N,N,N'',N''-四正辛基-N',N″-乙二基-双二苷酰胺(TOE-BisDGA)和N,N,N'',N''-四正辛基-N',N″-间苯二甲基-双二苷酰胺(TOX-BisDGA). 以磺化煤油和正辛醇混合溶液(体积比 90∶10)作稀释剂, 研究了它们在硝酸溶液中对Eu(Ⅲ)和Am(Ⅲ), 以及自身对HNO₃的萃取行为. 结果表明, 2种BisDGAs对HNO₃均有一定萃取, 当酸度不超过1.0 mol/L时, 二者形成1∶1型的萃合物. 随HNO₃浓度增加, Eu(Ⅲ)和Am(Ⅲ)的萃取分配比增加. 相同条件下, TOE-BisDGA对Eu(Ⅲ)和Am(Ⅲ)的萃取能力强于TOX-BisDGA. 斜率分析表明TOE-BisDGA和TOX-BisDGA与Eu(Ⅲ)和Am(Ⅲ)均形成2∶1型的萃合物. 温度升高, 萃取分配比下降, 萃取反应是放热反应. 2种BisDGAs对Eu(Ⅲ)的亲和力强于对Am(Ⅲ)的亲合力, 表明BisDGAs对Eu(Ⅲ)有一定的选择性. 同时, 研究了BisDGAs萃取Eu(Ⅲ)和Am(Ⅲ)的机理, 给出了表观萃取平衡常数和萃取反应热力学函数ΔH, ΔS和ΔG的值. 此外, 还对TOE-BisDGA和TOX-BisDGA与Eu(Ⅲ)形成的配合物进行了红外和紫外光谱分析.     

基于离子型铱配合物的发光电化学池

基于离子型过渡金属配合物的发光电化学池在信息显示和固体照明方面极具应用前景,因此其相关材料的设计、开发和器件性能的提高等工作在近几年引起了人们广泛的研究兴趣。在各类离子型过渡金属配合物中,离子型铱配合物由于发光效率高,发光颜色容易调节等优点而受到广泛关注。本文综述了近几年来离子型铱配合物在发光电化学池中的应用进展,重点评述了不同发光颜色的发光电化学池的制备和器件的高性能化等方面的研究进展,并展望了基于离子型铱配合物的发光电化学池这一研究领域的发展前景。     

环金属铱配合物在发光电化学池中的应用

与有机电致发光二极管(OLED)相比,发光电化学池(LEC)的器件结构更加简单,可以采用高功涵金属作为电极,因此在照明领域和移动设备终端显示方面具有巨大的应用前景,与其相关的研究与开发越来越受到科学界的重视.基于离子型过渡金属配合物的发光电化学池,由于具有不需要额外添加离子型导电材料和可以充分利用单线态和三线态激子的优点,受到业界广泛关注.与其它离子型过渡金属配合物相比,离子型铱配合物具有发光效率高、光学稳定性好以及发光颜色容易调节等优点.综述了近10年环金属铱配合物在发光电化学池中的应用,重点对离子型铱配合物在发光电化学池中的应用进行了评述,并对环金属铱配合物在发光电化学池领域的发展进行了展望.     

外围取代基团对卟啉铂(Ⅱ)配合物发光性能的影响

设计合成了具有不同外围取代基的卟啉铂(Ⅱ)配合物PtTEMP, PtTBMP, PtOMPP和PtDMPP, 并对其结构和光电性能进行了表征. 晶体结构分析结果表明, 这些卟啉铂(Ⅱ)配合物具有较理想的平面配位构型, β-位叔丁基的引入有效抑制了分子间的π-π相互作用. 外围取代基几乎不影响配合物的吸收和发光性质, 最大发射峰位于646~656 nm之间, 为配体中心的 ³π^*-π磷光发射. 空间位阻效应更强的叔丁基取代配合物(PtTBMP)的溶液态荧光量子效率和外量子效率最高, 分别为0.58和6.3%. 3个甲氧基取代的PtDMPP的发光效率优于2个甲氧基取代的PtOMPP, 二者的溶液态荧光量子效率分别为0.36和0.29, 外量子效率分别为2.4%和1.7%.     

微生物铁氧化还原作用对水中砷锑去除影响的研究进展

砷锑污染在全球领域广泛存在,与常规的铁氧化物相比,微生物铁氧化生成的含Fe(Ⅲ)矿物对水中砷/锑(As/Sb)具有更强的吸附能力,并因其高效、实用和环境友好而具有广阔的应用前景,但微生物铁还原也可能导致被吸附的As/Sb再次释放。本文综述了微生物铁氧化还原作用对As/Sb去除影响的研究进展,归纳了铁矿物“合成-溶解-转化”的微生物循环过程以及该循环伴随的水中As/Sb固定、溶解与转化机理,整合了微生物合成Fe(Ⅲ)矿物的矿物学性质、对As/Sb固定的热动力学规律和络合机制,总结了微生物合成Fe(Ⅲ)矿物对As/Sb去除的影响因素,基于该研究的现存问题展望了利用微生物铁氧化还原作用去除As/Sb的发展方向。     

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.     

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.     

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%).     

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.     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

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.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.