硝酸辅助合成水溶性绿光碳点及其在pH测量与Fe3+检测中的应用

以柠檬酸、甲酰胺与浓硝酸为原料合成了绿色荧光碳点（CDs）,对其物相、形貌及荧光性能进行了表征,并研究了其在离子检测及荧光标记方面的应用。结果表明：所合成的CDs呈现良好的水溶性;当以360~460 nm波长的光激发时,该CDs发出明亮的绿色荧光,并且发射峰的位置不随激发光波长而改变,其量子产率高达44.2%;同时,该绿光CDs对pH敏感,体系pH值在4.5~8.5范围内时,其归一化荧光强度与pH间有较好的线性关系;此外,该绿光CDs对Fe³⁺有较好的选择性响应,在0~1 000 μmol·L^-1范围内,体系的荧光淬灭效率（I₀/I）与Fe³⁺浓度有良好的线性关系,检出限为9.8 μmol·L^-1。     

碳纸负载碳酸氢镍纳米颗粒的无酶葡萄糖电化学传感器

通过一步水热法在碳纸上原位生长碳酸氢镍纳米颗粒,利用粉末X射线衍射和扫描电子显微镜对材料的结构及形貌进行表征,发现碳纸上负载纯相Ni （HCO₃）₂时具有较多的催化活性位点,利于葡萄糖的催化氧化反应进行。循环伏安法和时间-电流响应曲线表明该电极的检测限为0.98 μmol·L^-1,线性范围为2.95~1.02 mmol·L^-1,灵敏度为935 μA·L·mmol^-1·cm^-2,同时具有优异的选择性及稳定性。此外,该传感器能够实现对乳制品中葡萄糖的快速检测。这些结果表明,过渡金属和导电基底的协同作用会增强复合材料整体的导电性能和催化性能。     

一个对2,4,6-三硝基苯酚和Fe3+离子具有双重荧光传感行为的层状镉(Ⅱ)-有机配位聚合物

通过水热法合成了一个由三连接的2,3-喹啉二甲酸桥联扭曲的Cd²⁺八面体形成的二维层状配位聚合物[Cd（QDA）]_n（1）。该配合物发射出较强的蓝色荧光并具有很高的热稳定性和化学稳定性。更为重要的是,该配合物在乙醇分散体系中可快速识别痕量的2,4,6-三硝基苯酚和Fe³⁺离子,其对2,4,6-三硝基苯酚的淬灭常数（K_sv）和检测限（LOD）分别为6.61×10⁴ L·mol^-1和0.83 μmol·L^-1,对Fe³⁺离子的淬灭常数和检测限分别为1.74×10⁴ L·mol^-1和2.70 μmol·L^-1。     

石墨烯/CdTe量子点复合物的合成及在克伦特罗检测方面的应用

成功地合成了石墨烯/CdTe量子点复合物,并采用透射电镜、紫外吸收光谱、荧光发射光谱、荧光衰减曲线和X射线光电子能谱对产物进行了表征。透射电镜结果显示CdTe量子点被修饰于石墨烯的表面;X射线光电子能谱结果表示石墨烯在合成过程中被还原,还表明在所合材料的表面具有羧基和羟基;荧光发射光谱和荧光衰减曲线的结果显示将CdTe量子点修饰于石墨烯表面显著提高了CdTe量子点的荧光性能。此外,基于克伦特罗和石墨烯/CdTe量子点复合物之间形成的氢键,所合成材料可用于定量分析克伦特罗。克伦特罗对石墨烯/CdTe量子点复合物具有显著的猝灭作用,荧光强度的降低（F₀/F）与克伦特罗之间存在良好的线性关系,线性范围为7.22~108.30 μmol·L^-1,检出限为4 μmol·L^-1。     

石墨烯/CdTe量子点复合物的合成及在克伦特罗检测方面的应用

成功地合成了石墨烯/CdTe量子点复合物,并采用透射电镜、紫外吸收光谱、荧光发射光谱、荧光衰减曲线和X射线光电子能谱对产物进行了表征。透射电镜结果显示CdTe量子点被修饰于石墨烯的表面;X射线光电子能谱结果表示石墨烯在合成过程中被还原,还表明在所合材料的表面具有羧基和羟基;荧光发射光谱和荧光衰减曲线的结果显示将CdTe量子点修饰于石墨烯表面显著提高了CdTe量子点的荧光性能。此外,基于克伦特罗和石墨烯/CdTe量子点复合物之间形成的氢键,所合成材料可用于定量分析克伦特罗。克伦特罗对石墨烯/CdTe量子点复合物具有显著的猝灭作用,荧光强度的降低（F₀/F）与克伦特罗之间存在良好的线性关系,线性范围为7.22~108.30 μmol·L^-1,检出限为4 μmol·L^-1。     

掺氮高荧光碳点的一步法制备及对痕量Hg(Ⅱ)离子的选择性检测

采用一步水热法制备了一种水溶性的、具有良好荧光性能的掺氮碳量子点(N-碳点),其尺寸大小均匀,约为7 nm。N-碳点的荧光强度随N的掺杂量、水热反应温度、溶液的pH值而改变。在最佳反应条件下所制备的N-碳点的荧光量子产率高达24.4%。该N-碳点作为一种简单、低成本的荧光探针用于检测痕量Hg²⁺,具有高选择性和高灵敏度的特点,其最低检测极限可达到0.02 μmol·L^-1 (4.012 ng)。     

固定漆酶聚苯胺-CoC2O4纳米复合物修饰电极的直接电化学

采用循环伏安法、微分脉冲伏安法、交流阻抗谱以及计时电流法等电化学方法,结合红外光谱、紫外-可见分光光度法、原子力显微镜、透射电子显微镜以及原子吸收光谱等辅助手段,表征了固定漆酶的聚苯胺-草酸钴纳米复合物的化学组成、结构和形貌,测试了纳米复合物固酶前后的导电性能的变化,研究了纳米复合物修饰电极上固定漆酶的直接电化学行为,评估了该电极的催化氧还原效能以及作为电化学传感器检测氧分子的性能。实验结果表明该电极在不含电子介体的溶液中以酶活性中心T2作为首要电子受体,将得到电子传递给化学吸附的氧气使其被电还原,其表观电子迁移速率为0.017 s^-1,且具有良好的催化氧还原性能（氧还原起始电位：460 mV vs NHE,转化氧分子为水的表观速率常数为2.6×10^-4 s^-1）,酶电催化氧还原为水分子步骤为反应的速控步。该电极作为电化学传感器对氧具有极低检测限（0.20 μmol·L^-1）,宽线性响应范围（0.4~7.5 μmol·L^-1）以及对底物高亲和力（K_M=122.4 μmol·L^-1）等优势。     

一例互穿的阴离子型In（Ⅲ）金属有机骨架用于选择性检测水中Fe3+离子

作为一类新型多孔材料,金属有机骨架（MOFs）常被开发作为荧光传感器用来监测水中的污染物,开发稳定且易制备的MOFs材料实现选择性检测有毒的Fe³⁺仍具有较高挑战。本工作中,我们报道一例水稳定的二重穿插In（Ⅲ）基MOF：（NH₂Me₂）[In （fdc）₂]·2H₂O （BUT-205,BUT代表北京工业大学,H₂fdc=呋喃-2,5-二羧酸）。BUT-205的构筑采用生物质衍生配体,其结构通过单晶X射线衍射确立。这个材料可作为高效的水相Fe³⁺离子传感器,具有高的灵敏度和选择性。检测限达到1.3 μmol·L^-1,低于美国环保局规定的饮用水中安全标准（15.7 μmol·L^-1）,并且该传感材料可以回收利用至少4次。     

基于多金属氧酸盐和多壁碳纳米管的双酚A电化学传感器的构建与性质

选择含N配体（L=1,3-双（1-咪唑）丙烷）与磷钼酸（H₃PMo₁₂O₄₀）水热合成了一个新的无机-有机杂化化合物（H₂L）₂（HL）₂L （PMo₁₂O₄₀）₂·2H₂O （PMo₁₂）。通过红外、热重、X射线光电子能谱、X射线粉末衍射和单晶衍射等对该化合物进行了表征。X射线单晶衍射表明该化合物为3D结构。将该化合物和多壁碳纳米管修饰在玻碳电极上构造了一种双酚A电化学传感器并对其传感性能进行研究。研究表明,在1~20 μmol·L^-1范围内,检出限为0.5 μmol·L^-1（S/N=3）,并且该传感器具有良好的抗干扰和稳定性。     

二氧化锰纳米颗粒调控的紫外可见吸收-荧光双通道传感器的构建及D-青霉胺的检测

以聚乙烯亚胺(PEI)同时作为模板和还原剂,基于原位氧化还原反应,一步法制备二氧化锰纳米颗粒(MnO₂ NPs),并对其形貌、组成、紫外可见吸收、催化氧化特性进行了表征。结果表明,MnO₂ NPs能够催化氧化邻苯二胺(OPD)为2,3-二氨基吩嗪(DAP),产生420 nm处的紫外可见吸收和560 nm处的荧光发射。D-青霉胺(DPA)中的活性巯基可与MnO₂发生特异性反应,还原降解催化剂,抑制其催化氧化活性,使得体系紫外可见吸收-荧光信号减弱甚至消失。基于DPA浓度与体系光谱信号变化的关系,我们建立了MnO₂ NPs介导的紫外可见吸收-荧光双通道传感DPA的新方法。荧光传感通道具有更好的线性范围和灵敏度,该方法线性范围为1~80 μmol·L^-1,检出限为0.54 μmol·L^-1。此外,MnO₂ NPs介导的荧光传感DPA应用于人体尿液样品分析中的回收率为98.31%~107.76%,证明了该方法的可靠性。     

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.     

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.     

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.