碳量子点/壳聚糖复合物的制备及用于槲皮素检测

以柠檬酸三钠、11-氨基十一烷、聚乙二醇400为碳源,利用微波法制备了碳量子点,将其与壳聚糖反应,制备出碳量子点/壳聚糖复合物。采用荧光、紫外、红外光谱等对碳量子点和碳量子点/壳聚糖复合物进行表征,探究了温度、时间、缓冲溶液及pH对体系荧光强度的影响。在pH 7.6的硼酸—硼砂缓冲介质中,槲皮素可使碳量子点/壳聚糖复合物发生荧光猝灭,其猝灭程度与槲皮素浓度呈良好的线性关系,据此建立了碳量子点/壳聚糖荧光猝灭法测定槲皮素的新方法,方法线性范围为4~40μmol/L,相关系数为0.9940,检出限为0.5μmol/L。方法已应用于测定本地甜瓜中槲皮素的含量。     

微波法制备氮掺杂碳点/海藻酸纳米复合物及其电沉积技术研究

以海藻酸为碳源,乙二胺为氮掺杂剂,采用简单方便的微波法制备得到氮掺杂碳点(N-CDs)/海藻酸纳米复合物.通过透射电镜观察到所制得的N-CDs/海藻酸纳米复合物有纳米粒子存在,它们的平均粒径为4.6 nm.荧光性能分析表明N-CDs/海藻酸纳米复合物在365 nm紫外光下呈现明显的蓝色荧光,并且其荧光发射性能具有激发光波长依赖性. N-CDs/海藻酸纳米复合物还保留了海藻酸与Ca~(2+)作用形成凝胶的性能以及与一些二价金属离子的配位能力,可以直接应用于阳极电沉积和配位电沉积.利用电沉积技术具有空间选择性和时间可控性的特点,可以在电极上构建不同形状和荧光图案的N-CDs/海藻酸电沉积膜,还可以对电沉积膜的厚度进行调控.此外,利用电沉积技术制备的N-CDs/海藻酸电沉积膜电极可用于进行电化学检测.     

光谱法研究CdSe/CdS/ZnS量子点与壳聚糖的复合

通过CdSe/CdS/ZnS量子点与壳聚糖之间的静电作用,用共混法制备了壳聚糖-CdSe/CdS/ZnS复合物.用荧光光谱、紫外-可见光谱、红外光谱对所得的壳聚糖-CdSe/CdS/ZnS复合物进行了表征.研究结果表明:壳聚糖-CdSe/CdS/ZnS复合物具有良好的光学性能.     

碳量子点标记的硼替佐米缓释制剂的合成与应用

硼替佐米的肽硼酸与壳聚糖的羟基发生酯化反应生成肽硼酸酯,即得到硼替佐米-壳聚糖复合物;然后,该复合物中壳聚糖的氨基与碳量子点表面羧基发生静电吸附作用,将碳量子点吸附进入壳聚糖体系内,进而得到硼替佐米-壳聚糖-碳量子点复合纳米粒载体.此产物具有生物相容性、无毒副作用、荧光示踪及pH敏感等性质,在生物传感、生物医用材料、功能纳米材料,尤其是药物载体或制剂的控制释放方面,具有重要的研究意义和应用价值.     

水溶性量子点的制备及其与壳聚糖衍生物的自组装

以3-巯基丙酸(HS-CH2CH2COOH)为稳定剂, 制备了水溶性的碲化镉(CdTe)量子点(QDs), 考察了制备条件对QDs荧光性能的影响及CdTe QDs与壳聚糖及叶酸和聚乙二醇改性的壳聚糖的自组装. 研究发现, 壳聚糖及改性壳聚糖与QDs的复合物荧光强度相对纯的CdTe QDs明显增强, 且QDs被包裹在内核, 复合粒子呈明显的核/壳结构. 改性壳聚糖/QDs复合物较小且尺寸分布更为均一.     

水相一步法合成具有双光子效应的高效橙红荧光聚合物碳点

聚合物碳纳米点是近年来新兴的一种荧光纳米探针,具有较低的生物毒性、良好的水溶性、较高的量子产率、优异的光/化学稳定性以及良好的生物相容性.目前所制备的碳点大都表现出蓝、绿色荧光发射.为实现碳点长波荧光发射,扩大其在生物标记与成像及光电显示方面的应用,本文采用水相一步法交联聚合反应制备了具有橙红荧光发射性质且具有双光子效应的聚合物碳点,发射波长为604 nm,荧光量子产率达到30.64%,并且应用在生物活体成像中.     

碳点的制备及在荧光分析中的应用

综述了碳点的制备方法、碳源材料以及碳点在荧光分析中的应用(包括生物成像、生物分子检测和金属离子检测)。碳点的合成方法包括自上而下法(电弧放电法、激光消融法、电化学合成法和酸氧化法)及自下而上法(微波法、水热法和超声法),并对碳点的发展前景进行了展望(引用文献79篇)。     

采用一锅法制备量子点/琼脂纳米复合凝胶

以天然高分子琼脂为稳定剂,采用简单便捷的一锅法制备Mn掺杂ZnS量子点/琼脂纳米复合凝胶,琼脂不仅作为制备量子点的稳定剂,同时也是纳米复合凝胶的主要成分。对该纳米复合凝胶中量子点的化学结构和尺寸大小进行了表征,并对纳米复合凝胶的荧光性能和凝胶性能进行了研究。实验结果表明,制备得到的纳米复合凝胶均一稳定,在302 nm紫外光下呈现十分明显的橙红色荧光。在该纳米复合凝胶的透射电子显微镜（TEM）表征中可以观察到大小比较均一、粒径为3 nm左右的纳米粒子,光谱分析结果进一步证实纳米复合凝胶中存在Mn掺杂ZnS量子点。该纳米复合凝胶不仅具有良好的荧光性能,还具有温度刺激响应性可逆溶胶-凝胶转变性能,同时具有较高的溶胶转变温度和较好的温度稳定性。利用这些性能特点,可以方便地制备纳米复合凝胶小球。此外,该纳米复合凝胶还可以被潜在应用于金属离子的荧光检测分析领域。     

一锅法制备量子点/琼脂纳米复合凝胶

以天然高分子琼脂为稳定剂,采用简单便捷的一锅法制备Mn掺杂ZnS量子点/琼脂纳米复合凝胶,琼脂不仅作为制备量子点的稳定剂,同时也是纳米复合凝胶的主要成分。对该纳米复合凝胶中量子点的化学结构和尺寸大小进行了表征,并对纳米复合凝胶的荧光性能和凝胶性能进行了研究。结果表明,制备得到的纳米复合凝胶均一稳定,在302nm紫外光下呈现十分明显的橙红色荧光。TEM表征显示,在该纳米复合凝胶中可以观察到大小比较均一、粒径为3nm左右的纳米粒子;光谱分析结果进一步证实纳米复合凝胶中存在Mn掺杂ZnS量子点。该纳米复合凝胶不仅具有良好的荧光性能,还具有温度刺激响应性可逆溶胶-凝胶转变性能,同时具有较高的溶胶转变温度和较好的温度稳定性。利用这些性能特点,可以方便地制备纳米复合凝胶小球。此外,该纳米复合凝胶还有望应用于金属离子的荧光检测分析领域。     

由蚕砂制备的碳量子点在不同激发、pH、金属离子、温度及极性环境下的荧光性质研究

碳量子点作为一种新兴的荧光纳米材料,具有粒径分布均匀、光稳定性好、激发-发射波长可调控、表面可修饰等优良的性质,兼具低毒性、生物相容性好等优点,在分析检测和生物成像等领域展现出广阔的应用前景。而蚕砂是家蚕的干燥粪便,简单易得。利用蚕砂作为碳量子点制备原料,采用微波合成的方法制备得到了一种平均水合粒径为4.86 nm,含氮、硫修饰的碳量子点材料,可作为针对激发波长、pH、金属离子浓度、温度及溶剂极性的变化有着显著响应特性的碳量子点型荧光探针。该探针的荧光最大发射波长随激发波长或pH的增加而红移;荧光强度随温度或pH的降低而增加;随着金属离子,特别是铜离子的加入而逐渐降低,并随着EDTA络离子的加入而逐渐回复。在多种溶剂中该探针均具有较好的溶解度,当换用不同极性的溶剂时,随着溶剂极性的增加荧光发射波长逐渐红移。荧光性质随多重环境参数变化为该碳量子点在未来的生物检测和成像领域提供了广阔的应用前景。     

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.