基于苯并吡喃腈的激活型半胱氨酸荧光探针

设计并合成了基于苯并吡喃腈为母体单元的近红外激活型荧光探针(E)-2-(苯并吡喃腈基)乙烯基-5-(二乙氨基)丙烯酸苯酯(DCM-AC),其结构中的丙烯酰酯键作为氨基酸激活反应的响应基团。 研究结果表明,探针分子DCM-AC对半胱氨酸具有高灵敏、选择性光谱响应,不仅能观察到明显的颜色变化,而且探针在710 nm处的荧光发射强度显著增强,相应的荧光增强比值与半胱氨酸的浓度(1.0~8.0 μmol/L)呈现良好的线性关系。 探针DCM-AC对半胱氨酸的检出限为2.8×10^-7 mol/L,能选择性检测半胱氨酸区别于结构类似的高半胱氨酸和谷胱甘肽,且不受其它氨基酸物质干扰。 通过质谱、核磁和紫外吸收光谱研究了DCM-AC检测半胱氨酸的反应激活机理:半胱氨酸先通过巯基与DCM-AC上的丙烯酰酯双键发生亲核加成,然后环化脱除内酰胺环状化合物。     

基于间苯二甲酰腙的荧光探针的合成及其接力识别Al3+和焦磷酸根

设计合成了一种基于2-羟基-1-萘甲醛和间苯二甲酰肼的简单高效的荧光探针L,其结构通过~1H NMR、~(13)C NMR和HRMS进行表征。在乙醇-水(1∶1)的体系中,L能够高选择性识别铝离子,表现出明显的荧光增强,并具有较低的检测限(5. 924×10~(-6)mol/L),二者结合比为1∶2。此外,原位生成的配合物L-2Al~(3+)可接力识别焦磷酸根(PPi),具有良好的选择性和灵敏度,检测限可达4. 756×10~(-5)mol/L。该荧光探针具有潜在的应用价值。     

一种基于硝基烯烃的硫醇荧光探针的合成及生物成像研究

生命体内小分子硫醇,如半胱氨酸(Cys)、同型半胱氨酸(Hcy)和谷胱甘肽(GSH),在多种生理和病理过程中发挥重要作用.以氟硼二吡咯(BODIPY)为荧光团,硝基烯烃为识别基团,经三步简单有机合成,构建了一个打开型硫醇荧光探针.密度泛函理论计算结果表明,硝基通过光诱导电子转移(PET)机制淬灭BODIPY荧光.光谱测试结果表明,探针与硫醇发生迈克尔加成反应,响应迅速,选择性好,灵敏度高,对GSH的检测极限低至11×10~(-9) mol/L.荧光共聚焦成像结果表明,探针可用于HeLa细胞和斑马鱼内源生物硫醇荧光成像研究.     

一种检测水合肼荧光探针的合成与应用

基于香豆素类染料,设计合成了一种具有较高选择性和灵敏度,可在生理条件(pH 7.4)下检测水合肼的荧光探针,同时利用核磁共振和高分辨质谱对探针的分子结构进行了表征。基于水合肼进攻探针分子结构中的4-丁酸酯,生成酚氧负离子,同时发生分子内环化反应后生成具有强烈荧光的亚胺香豆素,实现了探针分子对水合肼的检测。光谱学研究表明,当向探针溶液加入水合肼(0~100μmol/L)后,探针溶液在绿色光谱区域(502 nm)呈现一个显著的荧光增强响应(增强至55倍)。并且,探针可以检测相对较低浓度的水合肼,检出限为1.7×10~(-7)mol/L。此外,相对于其他阴离子和亲核试剂,探针对水合肼的识别显示出较高的选择性和灵敏度。探针成功实现了细胞内水合肼的荧光成像,证明其在细胞成像中具有潜在的应用能力。     

一种高灵敏及高选择性荧光“关-开”分析测定谷胱甘肽的方法研究

本文基于无荧光的N-丁基-4-硝基-萘酰亚胺(BNNA)能够选择性地与谷胱甘肽(GSH)发生硝基-巯基亲核取代反应,并生成强荧光的芳香硫醚产物,而十六烷基三甲基溴化铵(CTAB)胶束对该反应具有明显的催化及荧光增敏作用的原理,建立了一种以BNNA为荧光探针,选择性荧光"关-开"分析测定GSH的新方法。在优化的实验条件下,BNNA-GSH-CTAB体系在470 nm波长处的荧光强度(激发波长390 nm)与GSH浓度在0.1～10.0μmol/L范围内呈线性关系,检测限为1.35×10~(-9) mol/L,而且其他氨基酸,包括半胱氨酸(Cys)、高半胱氨酸(HCy)等对GSH的测定没有明显的影响。该方法具有荧光探针结构简单易得,Stockes位移大(80 nm),灵敏度高以及选择性强等特点,用于实际酵母样品中GSH的测定,加标回收率为94.4%～101.2%,相对标准偏差≤4.20%。     

基于黄酮醇的高选择性半胱氨酸荧光探针的合成及性能研究

报道了一种基于4’-二乙氨基黄酮醇、以丙烯酸酯为半胱氨酸(Cys)反应基团的荧光增强型探针A1,对Cys的检测响应快速(5 min内),能有效识别区分另外两种含巯基生物分子高半胱氨酸(Hcy)和谷胱甘肽(GSH)。探针溶液荧光强度与加入的Cys浓度呈线性相关,拟合方程为y=6.894x+0.8409(R~2=0.9973),检测限为1×10~(-7)mol/L。加入Cys后,探针溶液由浅色变为亮黄色,在自然光条件下实现对Cys的比色检测。检测机理推测为Cys对A1中的丙烯酰基进行了共轭加成并使酯键断裂,使荧光母体得到释放从而产生增强的荧光信号。探针A1可用于活细胞内对Cys的荧光成像分析。     

基于碳点荧光恢复法测定生物巯基化合物

碳点(CDots)是一种新型荧光纳米材料,Cu2+可以有效猝灭其荧光;而当有生物巯基化合物存在时,碳点-Cu2+体系的荧光可以恢复.基于此原理,我们成功地构建了检测生物体内总巯基化合物的新方法.该方法具有很好的选择性,常见氨基酸和金属离子对谷胱甘肽(GSH)、半胱氨酸(Cys)和高半胱氨酸(Hcy)的检测无影响.最佳实验条件下,谷胱甘肽、半胱氨酸、高半胱氨酸的浓度在6.0×10-6mol/L～1.0×10-4mol/L与相对荧光强度呈线性,R>0.996,检出限为2.0×10-6mol/L.该体系成功用于血清样品中总巯基化合物的检测.     

基于蛋白模板金纳米簇及羟基氧化钴纳米片的激活型荧光纳米探针用于免标记和灵敏检测生物硫醇

该文基于牛血清白蛋白模板金纳米簇（BSA@AuNCs）与羟基氧化钴（CoOOH）纳米片构建了一种激活型荧光纳米探针用于生物硫醇的检测。带负电的BSA@AuNCs能通过静电吸附作用组装到带正电的CoOOH纳米片表面,与此同时,BSA@AuNCs的荧光由于内滤效应（IFE）有效地被CoOOH纳米片猝灭,形成BSA@AuNCs－CoOOH纳米探针。当向纳米探针溶液加入生物硫醇（0.05～150 μmol/L）时,生物硫醇与纳米探针中的CoOOH纳米片发生氧化还原反应,CoOOH纳米片被降解生成Co2+,同时释放出BSA@AuNCs,BSA@AuNCs荧光信号恢复。结果表明,该纳米探针可以检测低浓度的生物硫醇,对生物硫醇（半胱氨酸、谷胱甘肽和高半胱氨酸）的检出限为30 nmol/L。相对于其他的氨基酸、金属离子及糖类化合物,该纳米探针对生物硫醇具有较高的选择性并成功应用于人血清样品中生物硫醇的检测。     

一种基于喹唑啉-4(3H)-酮的烯胺酮型荧光探针对CN~-的反应型识别研究

设计合成了一种基于喹唑啉-4(3H)-酮衍生物的烯胺酮型荧光探针QA。在DMSO溶液中,探针QA对CN~-具有高度的选择性识别作用,表现为荧光增强并蓝移,其识别机制为CN-对QA发生迈克尔加成反应。此外,探针QA对CN~-响应快速,检测限低至1.75×10~(-7)mol·L~(-1)。     

双罗丹明类衍生物荧光探针的合成及对Cu~(2+)的识别

设计并合成了一种可检测Cu~(2+)的新双罗丹明类衍生物荧光增强型分子探针(RG1),并用核磁和高分辨质谱(HRMS)对其结构进行了表征。通过紫外-可见光谱和荧光光谱研究了该荧光分子探针对Cu~(2+)的识别性能,结果表明:在体积比为1∶1的乙腈-水(10mmol/L Tris-HCl,pH=7.2)溶液体系中,探针RG1本身无色且荧光很弱,加入Cu~(2+)后,探针在553nm处出现强的荧光发射峰,溶液颜色从无色变为粉红色,对Cu~(2+)表现出好的选择性。此外,该探针可在较宽的pH范围(5~10)内直接检测Cu~(2+)的浓度。结果表明,Cu~(2+)浓度在3.0×10~(-6)~1.5×10~(-5)mol/L范围内与探针的荧光强度呈良好的线性关系,Cu~(2+)检出限为3.31×10~(-7)mol/L。同时对河水进行加标回收实验,得到了良好的回收率。     

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%.     

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.     

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.     

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.     

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.     

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.     

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.     

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.