荧光金纳米团簇的制备及其在汞离子检测中的应用

以牛血清蛋白(BSA)为还原剂和保护剂,制备了具有一定荧光性能的水溶性金纳米团簇(BSA-Au NCs),并对其结构和荧光性能进行了表征,同时还考察了合成时间和体系p H对荧光性能的影响。基于BSA-Au NCs对Hg~(2+)有一定的响应,建立了快速检测Hg~(2+)的新方法。Hg~(2+)浓度在一定的范围内(0.05~50μmol/L)与BSA-Au NCs荧光强度有着良好的线性关系。方法可用于实际水样中Hg~(2+)的测定。     

日光辐射光还原合成左旋多巴胺功能化的荧光发射的银纳米簇和铁离子检测

以左旋多巴胺(L-3,4-dihydroxyphenylalanine,DOPA)为稳定剂,采用日光辐射光还原法,合成了强荧光发射的银纳米簇(silver nanoclusters,Ag NCs)。透射电镜分析表明,所合成的Ag NCs表现亚纳米非晶态结构。Ag NCs在可见-近红外波长范围内(400~750 nm)有明显光吸收带,最大荧光激发和发射峰分别为550和630 nm,荧光量子产率为2.3%(相对于罗丹明B)。Ag NCs的荧光强度与合成时的日光辐射时间、DOPA浓度以及pH值等因素有关。进一步优化了合成Ag NCs的条件。基于荧光猝灭原理,所合成的DOPA功能化的Ag NCs能选择性地灵敏响应Fe3+。修饰在Ag NCs表面的配体DOPA能够选择性地结合Fe3+,导致Ag NCs显著聚集,伴随荧光猝灭。Ag NCs具有的较高量子产率和红荧光发射特性,有利于提高Fe3+的分析灵敏度。     

以DNA为模板的银纳米簇荧光检测及逻辑门的构建

以DNA为模板, 合成了具有荧光性质的银纳米簇(DNA-Ag NCs), 利用荧光光谱、 紫外光谱和红外光谱等手段对其进行了表征. 基于DNA-Ag NCs与离子相互作用时产生的荧光变化可实现对离子浓度的检测. 实验结果表明, 在最佳实验条件下, Ni ²⁺及Hg ²⁺的浓度与DNA-Ag NCs荧光强度呈线性关系; 并验证了该荧光探针用于检测自来水样品中汞离子和镍离子的实用性. 由于以DNA为模板的DNA-Ag NCs能够响应多种刺激, 如Ni ²⁺, S ^2-, Hg ²⁺和pH等, 利用相应的荧光强度可构建多输入的DNA-Ag NCs逻辑门及其组合逻辑门. 当荧光输出强度(I_output)>初始荧光强度(I_origin)时, 设定输出为1, 采用各种刺激及其组合作为输入, 构建了YES, INH和组合的NOR与INH逻辑门. 而只有当I_output≥I_origin时定义为输出为1, 可建立NOT, NOR, 组合的IMP加上NOR与AND逻辑门. 基于DNA-Ag NCs可以构建响应多元输入的复杂逻辑门, 实现化学信息的转变和传输, 在构建新的分子器件方面有较大应用前景.     

脯氨酸保护的铜纳米团簇的制备及其在三硝基苯酚检测中的应用

以脯氨酸(Pro)为保护剂,盐酸羟胺为还原剂,通过一步化学还原法制备脯氨酸稳定的铜纳米团簇(Cu NCs).采用分子荧光仪和紫外可见吸收仪对Cu NCs的光学性质进行分析,通过透射电子显微镜(TEM)、X射线光电子能谱(XPS)和傅里叶变换红外波谱仪(FTIR)对Cu NCs的结构进行表征.TEM图像显示Cu NCs的...     

金纳米团簇荧光材料的制备及其应用于测定食品中的过氧化氢

以胰蛋白酶作为保护剂和还原剂,在胰蛋白酶和氯金酸混合溶液中合成了具有红色荧光的水溶性金纳米团簇(T-Au NCs)。考察了合成时间以及胰蛋白酶溶液的质量浓度对T-Au NCs荧光性能的影响,确立了最佳合成条件。荧光光谱表征说明T-Au NCs的最大激发和发射波长分别为500,640nm,采用X射线光电子能谱表征了T-Au NCs中金的价态,并计算得到T-Au NCs的荧光量子产率为2.2%。基于过氧化氢对金纳米团簇的荧光猝灭作用,采用荧光光谱法测定食品中的过氧化氢残留量。过氧化氢的浓度的线性范围为0.050~1.00mmol·L~(-1),检出限为7μmol·L~(-1)。对4种食品中过氧化氢残留量的测定结果与国家标准方法的测定结果一致。     

硒化铜纳米晶体的高效抗菌活性研究

制备了十六烷基三甲基溴化铵(CTAB)包被的硒化铜纳米晶体(Cu_(2-x)Se NCs),并对其高效抗菌活性机制进行了研究。革兰氏阴性细菌大肠杆菌(Escherichia coli,E.coli)和革兰氏阳性细菌金黄色葡萄球菌(Staphylococcus aureus,S.aurues)被用作模型菌株,通过探究其最小抑菌浓度(MIC)和最小杀菌浓度(MBC),以及杀菌动力学评估了Cu_(2-x)Se NCs的抗菌性能。实验结果显示,金黄色葡萄球菌对Cu_(2-x)Se NCs更为敏感,这是由于大肠杆菌具有双层膜而金黄色葡萄球菌仅拥有单层膜。此外,当Cu_(2-x)Se NCs浓度为32μg/mL时,不管是革兰氏阳性菌还是革兰氏阴性菌,都会在1 h内全部死亡,证明Cu_(2-x)Se NCs拥有较强的杀菌性能。     

RhB/Chitosan/SiO_2荧光纳米粒子的制备及Cu~(2+)检测应用

采用反相微乳液法合成了Chitosan/SiO_2纳米粒子,通过振荡组装将荧光染料罗丹明B(RhB)固定于该纳米粒子上,制备成RhB/Chitosan/SiO_2纳米粒子。基于Cu~(2+)对Rh B/Chitosan/SiO_2纳米粒子的荧光猝灭作用建立了定量测定Cu~(2+)的荧光分析方法,探讨了测定机理,优化了实验条件。在优化条件下,Cu~(2+)浓度与体系荧光猝灭值在2. 4×10~(-7)～2. 5×10~(-5)mol/L范围内呈线性关系,线性方程ΔF=2. 98×10~7c+612. 11(r=0. 997),检出限为0. 22μmol/L (3s/k),方法用于延河水中Cu~(2+)的测定,加标回收率为98. 7%～103. 3%。     

基于银/铂纳米模拟酶表面修饰的铜离子比色检测方法研究

通过对银/铂纳米簇(Ag/Pt NCs)的表面修饰调控其催化活性,建立了一种高灵敏的比色法检测Cu2+.巯基丙酸能够抑制Ag/Pt NCs的催化活性,而巯基丙酸与Cu2+作用后,将导致上述抑制作用减弱.基于上述原理,通过测量Ag/Pt NCs 催化TMB-H2O2反应产生的显色信号,可以实现Cu2+的比色检测.本方法检测Cu2+的线性范围为10～100 nmol/L,检出限(3σ)为5.0 nmol/L.将本方法应用于实际水样中Cu2+的检测,结果表明,本方法具有操作简单、成本低、灵敏度高、特异性好等优点.     

Pyrene衍生物掺杂SiO_2荧光纳米粒子的制备及光物理性能

以泊洛沙姆(F-127)为模板剂,以硅氧烷化芘的衍生物4-(1-芘基)-N-[3-(三乙氧基硅基)丙基]丁酰胺(Pyrene-1)与正硅酸四乙酯(TEOS)的混合物为硅源,通过胶束模板法制备了Pyrene-1掺杂的SiO_2荧光纳米粒子.采用透射电子显微镜(TEM)、动态光散射仪(DLS)、紫外-可见分光光度计和荧光光谱仪等对Pyrene-1掺杂的SiO_2荧光纳米粒子的表观形貌、粒径分布和光物理性质进行了表征.结果表明,所制备Pyrene-1掺杂的SiO_2荧光纳米粒子粒径均一(TEM统计粒径约为12 nm,DLS表征的水合直径约为33 nm),在水中具有很好的分散稳定性.通过调节染料的掺杂比例可以有效调控染料分子间距.同时,由于染料分子被共价键固定在Si—O—Si骨架中,使Pyrene-1掺杂的SiO_2荧光纳米粒子的荧光量子效率大幅提高(从有机溶剂中的0.15提升至0.95),荧光寿命得以延长(从有机溶剂中的17.9 ns延长至191.8 ns).在染料掺杂比例较高时,通过生成激基缔合物(Excimer),形成了具有较大Stokes位移(~100 nm)的发光.     

Au24和Au25纳米团簇对二氧化碳电化学还原反应催化活性的分析

通过电化学催化过程将二氧化碳(CO2)还原为有用的燃料和化学品是目前降低CO2排放量以及高效利用CO2的主要方式之一.金纳米团簇(Au NCs)因其结构明确、原子级尺寸精确和高表面活性而被认为是CO2电化学还原反应(CO2RR)的良好催化材料和模型催化剂.本研究可控合成了两种金纳米团簇Au24 NCs和Au25 NCs...     

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.     

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.     

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.     

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.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

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.