二氧化钛催化超声波损伤牛血清白蛋白的研究

利用紫外可见(UV-Vis)光谱和荧光(FL)光谱研究了二氧化钛(TiO₂)催化超声波照射对牛血清白蛋白(BSA)的损伤作用，同时对金红石型和锐钛矿型TiO₂的催化性能进行了比较，并探讨了照射时间，TiO₂加入量，溶液酸度，超声波功率和离子强度等因素对BSA分子损伤的影响。结果表明，金红石型TiO₂的催化效果明显好于锐钛矿型TiO₂。在一定条件下，BSA分子的损伤程度随着照射时间的延长、照射功率和溶液酸度的增大而增大，而TiO₂的加入量和离子强度对BSA分子损伤的影响则较为复杂。     

热处理的锐钛型二氧化钛催化可见光照射损伤牛血清白蛋白

利用紫外-可见(UV-Vis)光谱和荧光光谱研究了可见光照射热处理的锐钛型二氧化钛(TiO2)对牛血清白蛋白(BSA)的损伤,同时对处理前后TiO2的光催化活性进行了比较,并考察了可见光照射时间、TiO2加入量和照射功率等因素对BSA分子损伤的影响。结果表明,经过高温处理锐钛型TiO2可以部分转晶,处理后的TiO2和可见光的联合作用能够导致BSA分子损伤。UV-Vis光谱表现为增色效应,荧光光谱表现为荧光猝灭。且处理后的TiO2的光催化活性好于处理前。对于体系温度为25℃和浓度为1.0×10-5mol/L的BSA溶液,BSA分子的损伤程度随着可见光照射时间、TiO2加入量和照射功率的增加而增大。同步荧光光谱证明了BSA分子中酪氨酸的损伤程度较大。     

热处理锐钛型二氧化钛催化可见光照射损伤牛血清白蛋白

利用紫外-可见（UV-Vis）光谱和荧光光谱研究了可见光照射热处理的锐钛型二氧化钛（TiO2）对牛血清白蛋白（BSA）的损伤,同时对处理前后TiO2的光催化活性进行了比较,并考察了可见光照射时间、TiO2加入量和照射功率等因素对BSA分子损伤的影响。 结果表明,经过高温处理锐钛型TiO2可以部分转晶,处理后的TiO2和可见光的联合作用能够导致BSA分子损伤。 UV-Vis光谱表现为增色效应,荧光光谱表现为荧光猝灭。 且处理后的TiO2的光催化活性好于处理前。对于体系温度为25 ℃和浓度为1.0×10-5 mol/L的BSA溶液,BSA分子的损伤程度随着可见光照射时间、TiO2加入量和照射功率的增加而增大。 同步荧光光谱证明了BSA分子中酪氨酸的损伤程度较大。     

不同受限状态下链硫醇的非线性光学响应

以和频(SFG)振动光谱技术探测了正十二硫醇(DDT)在不同受限状态下的分子振动信号, 包括金属基底上的自组装单层(SAM)分子, 放置在二氧化硅基底上的表面DDT化的金纳米粒子以及金纳米粒子的甲苯溶液. 在三种状态下都探测到了来自于DDT分子的振动光谱, 振动光谱的区别提供了在不同受限态下DDT分子的结构信息. 在金属基底上DDT分子排列规整, 放置在二氧化硅基底上的金纳米粒子表面的DDT分子具有一定的柔性, 在空气-甲苯溶液界面金纳米粒子表面的DDT分子高度无序. 此外, 光谱实验显示, 金纳米粒子表面的分子振动信号产生了局域场增强的效应, 相对于金基底上的自组装单层分子而言, 增强系数为10²-10³, 取决于光谱的偏振组合.     

Ag改性纳米ZnO薄膜及光催化活性

采用溶胶-凝胶法和光还原沉积贵金属法结合制备出Ag改性的纳米ZnO薄膜。利用FESEM、XPS、ESR、UV-Vis分析了纳米Ag-ZnO薄膜的表面形貌、表面组成和光谱特征。FESEM分析表明银在纳米ZnO薄膜表面形成原子簇而没有形成均匀覆盖层。XPS分析表明负载在纳米ZnO薄膜表面的银以Ag⁰形式存在; 相对于纳米ZnO薄膜, 纳米Ag-ZnO薄膜中晶格氧的含量有所下降,而表面羟基氧和吸附氧的含量显著增加。纳米Ag-ZnO薄膜的ESR峰强比纳米ZnO薄膜大,表明纳米Ag-ZnO薄膜中束缚单电子的氧空位的浓度高于纳米ZnO薄膜。UV-Vis分析纳米Ag-ZnO薄膜的紫外可见吸收光谱可能是纳米银粒子与纳米ZnO薄膜共同作用的结果。以甲基橙为模拟污染物,考察了纳米Ag-ZnO薄膜的光催化活性以及银沉积量对催化剂活性的影响。光催化降解结果表明,银的沉积量为0.018 2 mg·cm^-2的纳米Ag-ZnO薄膜的光催化活性最高,在紫外光照射3 h后甲基橙降解率约为78%,而纳米ZnO薄膜约为62%。     

在一维ZnO表面可控构建Co3Mn1纳米晶及其催化CO氧化性能

利用热分解法制备了结构明确的负载型纳米晶催化剂。在纳米晶成核和生长过程中加入一维ZnO纳米棒作为晶种,调控不同组分的纳米晶在 ZnO纳米棒表面均匀生长,从而获得了结构明确的 MnO/ZnO、Co₃O₄/ZnO、Co₃Mn₁/ZnO催化剂。透射电子显微镜(TEM)与 X 射线粉末衍射(XRD)结果显示,不同组分纳米颗粒都均匀分散在 ZnO 纳米棒表面。相对于 MnO/ZnO 和Co₃O₄/ZnO催化剂,Co₃Mn₁/ZnO催化剂在CO氧化反应中具有最佳的催化性能。在200 L·g_cat^-1·h^-1的气时空速下,Co₃Mn₁/ZnO催化剂起活温度为 50 ℃,其 T100(CO 转化率达到 100% 时的温度)为 200 ℃;利用 X 射线光电子能谱(XPS)对不同催化剂进行了分析,结果显示,Co₃Mn₁/ZnO催化剂的氧空位比MnO/ZnO催化剂提高了30%以上,从而使其具有较高的CO氧化催化性能。更为重要的是,Co₃Mn₁/ZnO复合纳米晶催化剂的活化能(39.4 kJ·mol^-1)远低于其它负载型纳米晶催化剂。     

磁性壳聚糖微球对牛血清白蛋白的吸附性能

在微乳液体系中, 以戊二醛为交联剂制备了磁性壳聚糖纳米粒子(Fe₂O₃-CS). 采用透射电子显微镜(TEM)、红外光谱(IR)、振动样品磁强计(VSM)等手段对纳米粒子进行表征. 结果表明, 纳米粒子的粒径在40 nm左右, 分散性良好, 具有较好的磁响应性能. 以碳二亚胺(EDC)为活化剂, 研究了Fe₂O₃-CS纳米粒子对牛血清白蛋白(BSA)分子的吸附性能, 并使用原子力显微镜(AFM)、紫外分光光度计(UV)进行表征. Fe₂O₃-CS粒子对BSA 的吸附大致符合Langmuir吸附模型, 298 K时饱和吸附量约为250 mg·g^-1, 吸附常数为0.007 L·mg^-1. 将BSA-粒子分散在不同pH的缓冲溶液中, 研究BSA-粒子复合物的稳定性. 用聚丙烯酰氨凝胶电泳(SDS-PAGE)对结果进行表征, 发现在碱性条件下BSA分子能从磁性粒子表面脱附下来.     

CoFe2O4纳米晶与牛血清白蛋白和牛血红蛋白的相互作用：吸附、纳米晶的团聚及蛋白构象的变化

水热制备了约10nm的CoFe₂O₄纳米晶,通过Zeta电势、动态光散射（Dynamic Light Scattering,DLS）和傅立叶变换红外光谱（FTIR）技术研究了纳米晶与牛血清白蛋白（Bovine Serum Albumin,BSA）和牛血红蛋白（Hemoglobin）的相互作用。纳米晶对BSA和血红蛋白都有很强的吸附,其中对血红蛋白的吸附符合静电吸附的规律,而对BSA的吸附则不符合静电吸附的规律。在pH=5.5和7.0时纳米晶对BSA和血红蛋白的吸附容量分别达到237.9mg·g^-1和256.9mg·g^-1。DLS结果表明蛋白质能够导致纳米晶团聚。吸附BSA或血红蛋白后,纳米晶的DLS粒径由51nm分别增大到472nm和114nm。CoFe₂O₄纳米晶还导致了蛋白质FTIR谱发生明显变化。BSA和血红蛋白的酰胺I带由于纳米晶的作用分别减少了4cm^-1和6cm^-1。     

加替沙星与牛血清白蛋白结合作用的光谱学研究

通过荧光猝灭光谱研究了15℃和37℃下水溶液中加替沙星（HGA）与牛血清白蛋白(BSA)的结合作用。由Stern-Volmer曲线计算出双分子猝灭速率常数分别为：K_q=9.28×10¹²L·mol^－1·s^－1(15℃)，K_q=8.51×10¹²L·mol^-1·s^-1 (37 ℃)。结果显示，HGA对BSA的荧光猝灭机理是一种静态猝灭过程。本文获得的热力学参数表明HGA主要以静电引力与BSA结合。HGA的浓度与BSA的荧光强度之间关系的研究表明，HGA与BSA按1 ：1摩尔比结合，结合反应的平衡常数K₀= 6.80×10⁴ L·mol^－1。另外，通过Förster原理计算了HGA与BSA的结合距离及能量转移效率。     

杂多酸盐K7[PTi2W10O40]·6H2O与牛血清白蛋白相互作用的研究

Under the imitated physiological condition of animal body, the interactions of heteropoly salt (PM-19) with bovine serum albumin (BSA) were investigated by fluorescence and absorption spectroscopy. It was shown that this compound had a quite strong ability to quench the fluorescence launching from BSA. After analyzing the fluorescence quenching data according to Stern-Volmer equation and Lineweaver-Burk double-reciprocal equation, we found that BSA had reacted with PM-19 and formed a certain new compound. The quenching belonged to static fluorescence quenching. According to Lineweaver-Burk equation, the forming constants of the compound (298 K: 2.68 × 10⁵ L·mol^-1; 304 K: 2.19 × 10⁵ L·mol^-1; 310 K: 1.82 × 105 L·mol^-1) and the thermodynamic parameters (ΔH=-24.72 kJ·mol^-1; ΔS=20.97 J·mol^-1·K^-1 / 20.92 J·mol^-1·K^-1/ 20.97 J·mol^-1·K^-1; ΔG=-30.97 kJ·mol^-1/ -31.08 kJ·mol^-1/-31.22kJ·mol^-1) at the corresponding temperatures were obtained. The latter shows that binding power between them is mainly electrostatic interaction. Based on F?rster′s non-radiation energy transfer mechanism, the binding locality (r=4.14 nm) was calculated between donor and accepter. The effect of PM-19 on the conformation of BSA was also analyzed by synchronous fluorescence spectroscopy.     

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.     

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.     

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.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

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.