荧光碳点与小檗碱类药物的作用及盐酸药根碱的选择性测定

荧光碳点因具有良好的生物相容性和抗光漂白等性质而广受关注.本文报道以血晶素为碳源、在氢氧化钠溶液中水热合成新的碳点,并且对其与小檗碱类生物碱的作用进行了深入探讨.研究发现,该方法制备的荧光碳点粒径分布于2~5 nm之间,具有激发光波长依赖的荧光,且该荧光可被小檗碱类生物碱猝灭.进一步研究其作用机理得知,碳点荧光猝灭源于小檗碱类化合物的吸收作用.其中药根碱猝灭碳点荧光同时可使发射峰红移,且其红移程度与药根碱浓度对数值在2.30~414?mol/L范围内呈良好的线性关系,检测限为1.06?mol/L.     

荧光碳量子点的绿色合成及高灵敏高选择性检测汞离子

本实验以苹果汁为原料,通过一步水热法合成得到了水溶性好及稳定性高的蓝色荧光碳量子点。研究发现Hg2+对碳量子点荧光有良好的猝灭作用,从而建立了一种快速检测Hg2+的新方法。实验发现在pH 7.0磷酸盐缓冲介质中碳量子点荧光猝灭强度与Hg2+浓度在5~100 nmol/L和1~50μmol/L范围内呈线性关系,检出限为2.3 nmol/L(S/N=3)。本方法可用于实际水样中Hg2+的测定。     

碳量子点荧光传感法测定牛奶中的三聚氰胺

基于碳量子点溶液荧光被汞离子猝灭后加入三聚氰胺又能恢复荧光的特性建立了一种测定三聚氰胺的简易方法。研究了碳量子点、碳量子点-Hg~(2+)和碳量子点-Hg~(2+)-三聚氰胺体系的Zeta电位,提出了该测试体系荧光猝灭与恢复是由碳量子点表面电荷改变引起的机理。研究了碳量子点浓度、猝灭剂汞离子用量、溶液pH、反应时间等因素对测定体系荧光猝灭与恢复的影响,确定了最佳测定条件。在最佳测定条件下,三聚氰胺在0.05~4.0μg/mL浓度范围内与体系荧光恢复程度呈线性关系,其线性方程为:y=1.135+0.9673c,线性相关系数R~2=0.9966,检出限为0.01μg/mL,能满足实际样品中三聚氰胺检测的要求。     

碳量子点荧光猝灭法检测铁离子

以甘油为碳源,采用一步水热法合成稳定性高,水溶性好的蓝色荧光碳量子点,基于Fe3+对碳量子点的荧光猝灭效应,建立一种快速、选择性检测Fe3+的新方法.研究表明,Fe3+对碳量子点的荧光猝灭程度与Fe3+浓度在0.005～1.2 mmol/L内呈良好的线性关系(R2=0.995),检出限为2.2 μmol/L.将其应用于补铁药中铁含量的测定,标准偏差为0.41 mg/tablet,加标回收率为95.5％～101.0％,其结果与邻二氮菲法测定结果相符.     

荧光猝灭法测定替硝唑的含量

B-R缓冲溶液中,替硝唑可使十二烷基硫酸钠（SDS）的荧光猝灭,据此建立了荧光猝灭法测定替硝唑含量的方法.实验结果表明：在pH5～8缓冲溶液中,替硝唑浓度在0.2～5.0 mg·L^-1范围内与体系的荧光猝灭强度呈现良好的线性关系（R=0.998 4）,对浓度为0.2 mg·L^-1的替硝唑平行测定11次,检出限为6.4×10^-3mg·L^-1,RSD=1.91%,该法简便,快速,用于药物制剂中替硝唑含量的测定,结果满意.     

基于锰掺杂量子点的噁喹酸荧光共振能量转移检测研究

基于噁喹酸对锰掺杂硫化锌量子点的荧光猝灭作用,建立了一种噁喹酸荧光共振能量转移检测方法。噁喹酸对量子点的荧光猝灭是由于生成了新的复合物而造成的静态猝灭,二者相互作用过程中焓变ΔH<0,熵变ΔS<0,分子间作用力为氢键或范德华力。在0~65μg/L线性范围内,噁喹酸质量浓度与量子点荧光抑制率呈现良好的线性关系(R²=0.9911),检出限为0.53μg/L。分别在5μg/L和25μg/L 2个浓度进行加标回收,平均加标回收率为92.2%~96.8%,相对标准偏差为0.6%~2.5%。该方法可应用于水环境中喹啉酮类杀菌剂噁喹酸的快速测定。     

荧光猝灭法测定壳聚糖含量

在pH 6.3的NaH2PO4-Na2HPO4缓冲溶液中,壳聚糖对荧光素的荧光强度具有明显的猝灭作用,且在一定浓度范围内,其猝灭程度与加入的壳聚糖浓度成线性关系,据此建立了一种新的测定壳聚糖含量的荧光猝灭分光光度法。该方法的回归方程为ΔF=64.02+42.28ρ(mg/L),R2=0.9942,线性范围为0.50~10.0 mg/L,检出限为0.27 mg/L。样品测定的RSD为4.5%(n=6),平均回收率为99.3%。采用该方法可测定复杂样品中的壳聚糖含量。     

氮掺杂碳纳米粒子的制备及在游离氯检测中的应用

以蔗糖和尿素为前驱体,在油酸介质中通过溶剂热法一步合成了氮掺杂碳纳米粒子,量子产率为15.1％.基于次氯酸对氮掺杂碳纳米粒子的快速、高选择性猝灭,建立了定量测定水中游离氯含量的新方法.次氯酸浓度在0.05～25.00 μmol/L范围内与氮掺杂碳纳米粒子的荧光猝灭率呈良好的线性关系,检出限(S/N=3)为23 nmol/L.本方法可应用于实际水样中游离氯含量的测定.     

核固红荧光猝灭法测定壳聚糖含量

在pH3.8的醋酸-醋酸钠缓冲介质中,壳聚糖对核固红的荧光强度有明显的猝灭作用,且在一定浓度范围内,壳聚糖的质量浓度与荧光猝灭程度呈线性关系,据此建立了荧光猝灭法测定壳聚糖含量的新方法。方法的线性范围为0.008～2.5mg/L,检出限为5.4μg/L。对猝灭机理进行了初步探讨,并将方法用于保健食品中壳聚糖含量的测定,回收率高,结果满意。     

CdTe量子点酸度敏感荧光探针测定水样中铵根离子含量

本研究在水相中合成了高质量的巯基乙酸包被的CdTe量子点.在pH 5.8～8.0范围内的PBS缓冲溶液中,CdTe量子点荧光强度与体系酸度存在良好的线性关系.利用NH+4 对量子点荧光的猝灭作用,实现了对水溶液中NH+4 的定量检测.在最优条件下,CdTe量子点酸度敏感探针荧光的猝灭程度与NH+4浓度呈良好的线性关系,线性范围为0.05～6.0 mmol/L,检出限为0.15 μmol/L.对1.0 mmol/L标准溶液平行测定11次,相对标准偏差为3.2%.利用标准加入法对水样中NH+4含量进行了测定,其结果与蒸馏-酸滴定法的结果基本一致.     

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%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

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.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

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.     

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.     

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.