手性碳量子点的制备及其应用

手性碳量子点(CQDs)因兼具优异的荧光性质、良好的生物相容性、较低的毒性、易于功能化以及手性特征等,在催化、检测和生物医学等领域具有广阔的应用潜力。目前,通过一步法或两步法制备的手性CQDs,已应用于手性催化、手性检测、高尔基体靶向成像、选择性调控酶和蛋白活性、选择性调控细胞能量代谢和促进植物生长等领域。然而,手性CQDs的发展初露头角,需进一步完善可控合成工艺,制备高荧光量子产率的长波长手性CQDs,使其在生物医学等领域绽放异彩。     

基于碳量子点的绿色合成及生物成像研究进展EI北大核心CSCD

碳量子点(CQDs)作为碳纳米材料家族成员之一,因其原材料广、成本低廉、较高的光致发光性能和良好的生物相容性,在研究和应用领域都受到了广泛的关注,是应用于生物成像的理想材料。CQDs的绿色合成是指采用环保型或无毒型原料,通过绿色合成方法,如炭化法、微波法、水热法等,合成具有荧光性能的无毒碳量子点,与传统的化学氧化、激光烧蚀、热解处理等方法相比,更加绿色环保、经济,其应用已成为研究热点。本文对碳量子点材料特性、绿色合成过程机理、绿色合成原料来源、合成方法,及其在癌细胞、微生物细胞等细胞成像方面的应用进行了综述,探讨了绿色合成CQDs的利弊问题,并提出了今后该研究领域面临的机遇与挑战。     

CQDs/TNS复合光催化剂的制备及其可见光催化活性

以明胶为原料用水热法一步合成了碳量子点(CQDs),经过聚乙二醇表面修饰后,在乙醇溶液中与二氧化钛纳米片(TNS)复合形成了碳量子点高分散负载的CQDs/TNS复合光催化剂.对复合光催化剂进行了XRD、FT-IR、HRTEM和XPS表征,结果表明合成的碳量子点的平均粒径为4nm且具有较好的荧光性能.与纯TNS相比,CQDs/TNS复合光催化剂在可见光下对罗丹明B表现出很好的光催化降解活性.当CQDs/TNS复合光催化剂中CQDs含量为7.5%时光催化活性最好,并且在3次循环降解后活性仍保持不变.其优异的光催化活性来自于碳量子点的独特上转换荧光性能和二氧化钛纳米片高活性{001}晶面的共同作用.     

碳量子点的生物毒性研究进展

作为一类新型碳纳米材料,碳量子点(CQDs)以其纳米尺寸效应、高水分散性、高荧光稳定性等优异特性及其低生产成本引起了科学界的广泛关注,成为国内外化学、材料学及生物科学等领域的研究热点.CQDs已被证实在生物传感、生物成像、药物载体、光催化等众多研究方向具有优异的应用价值.但是,也正是因为CQDs的广阔应用前景,尤其是在生物、医药及环境等领域的应用,增强了对其潜在的生物毒性进行研究评估的必要性.此外,在生产、使用、废弃和回收过程中,CQDs将不可避免地进入自然环境中,其高水分散性,其对自然环境,尤其是水环境的潜在生态影响需要得到重视.目前针对CQDs的生物毒性研究主要涉及对细胞、细菌、水生生物(藻类和鱼类)及陆生生物(大鼠、小鼠)等的影响.明确CQDs的生物毒性及其生态效应,对于正确理解和评估其环境风险,合理规划其使用和回收具有重要意义.本文阐述了这一领域的相关研究成果,并对其研究前景进行了分析和展望.     

碳量子点的荧光发射机制

碳量子点(CQDs)一般是指粒径小于10 nm的零维碳材料,因其具有优良的光学特性而在生物成像、光学器件、生物复合材料和生物传感等领域得到广泛应用,并有望成为未来应用最广泛的一种碳材料。CQDs的光学特性受粒径、表面官能团及合成的条件(如温度、溶剂的种类和pH等)的影响,为了精准调控其光学性能以及进一步扩大其应用范围,需对其光致发光(Photoluminescence,PL)机制进行详细研究。然而,CQDs的PL机制尚不完全明确,目前,已提出的PL机制有量子限域效应、表面态发射、碳核和荧光分子、多环芳烃分子发射、自陷激子模型、表面偶极子发射中心、聚集发射中心、多发射中心、缓慢的溶剂弛豫和溶剂化效应等。但这些发光机制都只能在一定程度上解释CQDs的部分PL现象,还没有一种机制能解释CQDs的所有PL现象,严重制约了对CQDs光学特性的调控。本文对CQDs不同的PL机制进行分类和总结,希望为进一步阐明其PL机制及实现CQDs 光学特性的可控调节提供参考。     

碳量子点的制备及其在能源与环境领域应用进展

碳量子点(carbon quantum dots,CQDs)作为碳纳米材料家族的新成员引起了科学家广泛关注和极大的研究兴趣。 CQDs具有优良的光学特性、生物相容性及微弱的细胞毒性,在生物医药、生物传感器及光电子设备、环境及能源等领域中具有重要的应用。 本文从CQDs的制备方法出发,介绍了近年来发展的新型制备方法,讨论了其优缺点以及对所得CQDs在组成、结构和性质等方面的影响;基于CQDs独特的光学及电化学性能,重点介绍了CQDs在环境与能源领域的应用。 此外,对CQDs研究过程中存在的若干挑战进行了分析,提出了未来发展的一些思考和建议,为拓展CQDs多方面应用提供重要参考。     

纳米碳点的制备与应用研究进展

纳米碳点是碳纳米材料家族的新成员,近年来在国内外受到广泛关注。与传统的荧光染料和半导体量子点发光材料相比,碳点不仅具有优异的光学性能及尺寸效应,且具有制备成本低廉、生物相容性好、易于官能化、能带结构可调等优势。本文在理清有关碳点概念的基础之上,介绍了碳点结构特征和制备策略,着重综述了纳米碳点在生物成像与诊疗、传感器件、催化、光电器件和能量存储领域的最新研究进展,探讨了碳点研究目前存在的问题及未来的发展方向。     

荧光碳点的生物效应及其应用研究进展

作为碳纳米材料的新成员,荧光碳点自发现以来以其独特的光学性能和生物效应引起了人们广泛的关注.新型荧光碳点表面经过钝化修饰后,被赋予相关的反应活性及靶向选择性.此外,荧光碳点更具有较低细胞毒性及优异的生物相容性,使碳点的应用日益多样化,特别在生物医学领域具有广阔的应用前景.本文对荧光碳点在生化分析、微生物检测、生物成像及疾病诊断治疗上的应用研究进展做了详细的论述.     

碳点荧光探针的制备及其在食品分析中的应用

碳点作为一种新型荧光碳纳米材料,具有优良的光学性能和小尺寸特性,以及良好的生物相容性、低毒性以及易于实现表面功能化等特点,是潜在的可以代替传统半导体量子点等荧光探针的良好选择.基于其独特的荧光特性和高灵敏度,碳点荧光探针在食品分析领域具有很好的应用潜力.本文对近年来荧光碳点的研究进展进行了综述,简述碳点的性能并对碳点的制备方法进行总结对比,重点介绍了碳点荧光探针在食品分析领域的应用,对目前碳点应用的限制进行了分析,对其发展前景和展望.     

碳点的设计合成、结构调控及应用

碳点是一类环境友好且性能独特的纳米粒子, 在光电转换、 生物医学、 催化及储能等领域的研究日益活跃. 碳点主要分为碳量子点(CQDs)、 石墨烯量子点(GQDs)和碳化聚合物点(CPDs), 其中CPDs作为一种新型碳点, 具有合成原料广泛、 碳化程度及共轭结构可调且材料相容性好等优点. 本文综合评述了近年来碳点尤其是CPDs的合成方法; 阐述了通过选择前驱体分子、 控制反应条件及掺杂原子等手段实现对其碳化和共轭程度、 晶格和能级结构的调控, 从而建立碳点及其杂化与复合材料微纳结构与性能之间的关系; 最后, 介绍了碳点在生物标记与成像、 光(电)催化、 光电转换及储能等领域的应用, 并对碳点领域的发展前景进行了展望.     

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%.     

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.     

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.     

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.     

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.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

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%).     

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.