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.     

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.     

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.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.