新型多杂臂超支化聚缩水甘油的简易合成及自组装行为

一种新型的两亲性多杂臂超支化聚缩水甘油(HPG-h-arm)可以通过简单的三部反应制备: 先利用阴离子开环聚合制备HPG核, 再利用1,3-二环己基碳化二亚胺(DCC)缩合反应一步同时将疏水性的棕榈酸(PA)链和活性溴接枝到HPG上面, 最后利用原子转移自由基聚合反应(ATRP)将亲水性的聚(N,N-二甲氨基甲基丙烯酸乙酯) (PDMAEMA)链接枝到HPG表面. 红外光谱(FTIR), 核磁共振(1H-NMR)和凝胶渗透色谱仪(GPC)证实了HPG-h-arm被成功制备. 利用动态光散射仪(DLS), 透射电子显微镜(TEM)和原子力显微镜(AFM)研究了HPG-h-arm在不同溶剂中的自组装行为和形貌. 结果表明HPG-h-arm在不同的溶剂中可以自组装得到不同尺寸的球状胶束.     

基于二氧化硅球腔微电极阵列的过氧化氢生物传感器制备

以聚苯乙烯(PS)微球阵列为模板,采用溶胶-凝胶法在氧化铟锡( ITO)电极上制备了二氧化硅(SiO2)球腔阵列,扫描电镜显示此方法制备的SiO2球腔阵列高度有序.电化学研究结果表明,该球腔阵列的循环伏安曲线符合微电极阵列的电化学特点.将血红蛋白(Hb)作为氧化还原模型蛋白直接吸附于球腔内,制得电流型过氧化氢(H2O2...     

可视化阵列传感器技术鉴别不同香型白酒

决定白酒香型的物质种类繁多,成分复杂.采用可视化阵列传感器技术对中国白酒五大香型的代表酒样进行检测,在可视化区分的基础上采用分层聚类分析、主成分分析等统计分析方法,对检测结果进行分析.不同香型的白酒在聚类分析中可以正确归类,利用主成分分析得到的前3个主成分所代表的白酒75.8%的信息量就可以将不同香型白酒完全区分开,表...     

高光谱图像技术检测黄瓜叶片的叶绿素叶面分布

以黄瓜叶片为材料,利用高光谱图像技术结合独立分量法(ICA),研究了叶绿素浓度叶面分布的快速、无损检测方法.用高光谱相机采集了80片黄瓜叶子的高光谱图像(408～1117 nm),利用ICA方法提取了高光谱图像的8个独立分量信号,通过逐步线性回归(SMLR)优选出第1、第2和第5个ICA信号,并在此基础上建立了叶绿素浓...     

分子印迹聚合物负载纳米金催化剂的制备及其底物识别性能

以4-硝基苯甲醇与氯金酸的络合物为模板,利用聚合物空腔内胺基捕获NaBH4还原的纳米粒子,设计和制备了一种具有底物识别性能的分子印迹聚合物负载纳米Au催化剂(Au/MIP).运用红外光谱、紫外-可见光谱和扫描电镜等方法对催化剂进行了表征.同时以水为溶剂,过氧化氢为氧化剂,考察了催化剂在取代苯甲醇氧化反应中的催化性能.结...     

常压高频放电等离子体炬改进制备CO2/CH4重整用Ni/MgO催化剂

比较了常规法、等离子体炬法和等离子体炬辅助焙烧法制得的Ni/MgO催化剂上CO2/CH4重整反应性能差异,并利用X射线衍射、透射电镜、X射线光电子能谱和CO2程序升温表面反应等技术对反应前后催化剂进行了表征,结果表明,采用等离子体炬辅助焙烧法制备的催化剂上Ni晶粒粒径小,分散度较高,低温活性和抗积炭性能较高;在常压,7...     

On the catalytic mechanism of Pt 4+/? in the oxygen transport activation of N2O by CO

The two-state reaction mechanism of the Pt₄^+/− with N₂O (CO) on the quartet and doublet potential energy surfaces has been investigated at the B3LYP level. The effect of Pt₄ ⁻ anion assistance is analyzed using the activation strain model in which the activation energy (ΔΕ ^≠) is decomposed into the distortion energies (\Updelta E ¹ _\textdist ) (\Updelta E^{ \ne }_{\text{dist}} ) and the stabilizing transition state (TS) interaction energies (\Updelta E ¹ _\textint ) (\Updelta E^{ \ne }_{\text{int}} ) , namely \Updelta E ¹ = \Updelta E ¹ _\textdist + \Updelta E ¹ _\textint \Updelta E^{ \ne } = \Updelta E^{ \ne }_{\text{dist}} + \Updelta E^{ \ne }_{\text{int}} . The lowering of activation barriers through Pt₄ ⁻ anion assistance is caused by the TS interaction \Updelta E ¹ _\textint \Updelta E^{ \ne }_{\text{int}} (−90.7 to −95.6 kcal/mol) becoming more stabilizing. This is attributed to the N₂O π*-LUMO and Pt d HOMO back-donation interactions. However, the strength of the back-donation interactions has significantly impact on the reaction mechanism. For the Pt₄ ⁻ anion system, it has very significant back-bonding interaction (N₂O negative charge of 0.79e), HOMO has 81.5% π* LUMO(N₂O) character, with 3d orbital contributions of 10.7% from Pt₍₃₎ and 7.7% from Pt₍₇₎ near the ⁴TS4 transition state. This facilitates the bending of the N₂O molecule, the N–O bond weakening, and an O⁻(²P) dissociation without surface crossing. For the Pt₄ ⁺ cation system, the strength of the charge transfer is weaker, which leads to the diabatic (spin conserving) dissociation of N₂O: N₂O(¹∑⁺) → N₂(¹∑_g⁺) + O(¹D). The quartet to doublet state transition should occur efficiently near the ⁴TS1 due to the larger SOC value calculated of 677.9 cm⁻¹. Not only will the reaction overcome spin-change-induced barrier (ca. 7 kcal/mol) but also overcome adiabatic barrier (ca. 40.1 kcal/mol).Therefore, the lack of a thermodynamic driving force is an important factor contributing to the low efficiency of the reaction system.     

Theoretical investigations of spin-orbit coupling and intersystem crossing in reaction carbon dioxide activated by [Re(CO)2]+

In order to further explore the detailed reaction mechanism of carbon dioxide activated by [Re(CO)₂]⁺ complex, CCSD(T) methods was performed to determine related potential energy surface (PES). Crossing point is determined by using a partially optimized method. The result shows that larger spin-orbital coupling (155.37 cm⁻¹) and intersystem crossing probabilities in spin-forbidden region causes the electron to spin flip at the minimum energy crossing point and access to the lower singlet PES. Nonadiabatic rate constant k is estimated to be quite rapid, so transition state (¹TS1) is rate-controlled steps. In addition, the electronic structure of oxygen-atom transfer process is further analyzed by localized molecular orbital and Mayer bond order. The analysis finds that the form of main bonding orbital is the electron contribution from the p(O) in CO₂ to the empty d(Re) orbital.     

浓硫酸催化合成叔丁基苯

利用浓硫酸催化叔丁醇和苯的反应,得到叔丁基苯;利用正交法优化了反应条件,利用气相色谱法测定了产物收率.结果表明,将叔丁醇滴加到苯-浓硫酸混合溶液中,控制叔丁醇与浓硫酸物料摩尔比为1:1、苯的用量为50 mL、浓硫酸用量为8.0 mL、反应温度为50℃、搅拌时间为4 h,目标产物的收率可达62.0%.     

新型C-异戊烯基香豆素的合成

以7-羟基香豆素或7-羟基-4-甲基香豆素为原料,通过异戊烯基化反应合成了四个新的C-异戊烯基香豆素,其结构经1H NMR,IR和MS表征.