12β-Acetyloxyperforatin,a New Limonoid from Harrisonia Perforata

A new A, D-seco limonoid, named 12-acetyloxyperforatin (1), along with three known ones, were isolated from the leaves of Harrisonia perforata. Their structures were elucidated on the basis of spectroscopic analysis, including extensive NMR techniques and computational modelling. These compounds showed no inhibitory activity against the 11β-HSD1 enzyme.     

含吗啉基片段的水杨醛席夫碱类化合物的合成及其淬灭1,1-二苯基-2-三硝基苯肼自由基性能

通过3-氟-4-吗啉基苯胺和取代水杨醛缩合反应,合成了14个含吗啉基片段水杨醛席夫碱类化合物(Ⅰa-Ⅰn)。通过核磁共振波谱仪(NMR)、傅里叶变换红外光谱仪(FTIR)、液相色谱-质谱联用仪(LC-MS)和元素分析等技术手段研究了产物的结构和淬灭1,1-二苯基-2-三硝基苯肼(DPPH)自由基的活性。 结果表明,在0.02~0.10 g/L,所有化合物均表现出一定的淬灭DPPH自由基活性。 其中,化合物Ⅰd和Ⅰf表现出较为优异的性能,化合物Ⅰd的活性在30%~55%,化合物Ⅰf的活性则大于50%。 随着化合物Ⅰd、Ⅰh、Ⅰj和Ⅰn质量浓度的增大,其淬灭DPPH自由基的活性均呈现增强趋势。     

手性锌卟啉对咪唑类客体分子识别的构象研究

Chiral recognition is an attractive subject in the area of host-guest chemistry. Conformation study is performed to understand chiral recognition of zinc(Ⅱ) porphyrin with imidazole derivatives on a molecular level. The molecular recognition of three novel chiral zinc porphyrin(1-3) with four types of imidazole derivatives was studied. The conformation searching of this host-guest system was studied by using simulated annealing method on the basis of Tripos force field. The different minimal energy conformation of imidazole combind with porphyrin was studied. The quantum chemistry calculation was performed to calculate the single-point energies of the host-guest system. The minimal energy conformation of ZnT(o-BocAla)APP (3)-Im showed that Im attaching from the single-side chain of the host had the reasonable configuration than that from the three-side chain. The former also had the lower energy than the latter. And the quantum chemistry calculation results of orbital energy, ΔE_L-H, and atomic net charge revealed the same way. The results illumate that combination oriention of the host-guest system is the single chain of the hosts.     

耐晒大红BBN与表面活性剂双组分光催化降解

以表面活性剂十六烷基三甲基溴化铵(CTAB)和难溶有机颜料耐晒大红BBN(简称BBN)为双组分降解底物, 以TiO2为光催化剂, 研究双组分底物的光催化降解的快慢及规律, 双组分降解的相互影响, 初步建立双组分和催化剂之间的作用模型. 结果表明, pH值及底物的浓度对双组分体系的降解都有显著影响, 碱性条件更适合体系的降解, 在中性(pH=6.8)环境中两种底物的降解效果明显高于单组分的降解. 在碱性条件下(pH=9.2), 加入BBN使CTAB的降解速率略有下降. CTAB的浓度对BBN褪色速率影响较大, 当CTAB 的浓度为1 cmc 时, BBN和CTAB的降解速率都达到最快. BBN在TiO2表面吸附性强, 且被优先降解.     

Spectroscopy, NMR and DFT studies on molecular recognition of crown ether bridged chiral heterotrinuclear salen Zn(II) complex

A barium-containing crown ether bridged chiral heterotrinuclear salen Zn(II) complex BaZn2L(ClO4)2, where L is a folded dinuclear chiral (R,R)-salen ligand, has been synthesized and characterized by elemental analysis, 1H NMR, UV-vis, IR, circular dichroism (CD) spectra, and mass spectra. As a folded dinuclear chiral host, its recognition with achiral guests (imidazole derivatives), rigid bidentate guest (1,4-diazobicyclo[2,2,2]octane, DABCO) and chiral guests (amino acid methyl esters) was investigated by means of UV-vis spectrophotometric titration, CD spectra. The association constants of D-amino acid methyl esters are found to be higher than those of their L-enantiomer. The sandwich-type binding of BaZn2L(ClO4)2-DABCO supramolecular assembly was specially studied via 1H NMR titration and 1H ROESY. To understand the recognition on molecular level, density functional theory (DFT) calculations on B3LYP/LanL2DZ were performed on the minimal energy conformations of host, guests, and host-guest complexes. The minimal energy conformations were obtained by molecular mechanics (MM) optimization and molecular dynamics (MD) simulation. The results of single point energy, HOMO energy, and charges transfer were analyzed. The results of theoretical calculations are in good agreement with the experimental data.     

Inhibiting effect of carbonate on the photoinduced flatband potential shifts during water photooxidation at TiO2/solution interface

Journal of Solid State Electrochemistry - The TiO2/solution interfacial junction is of scientific and practical importance in the field of photoelectrochemical water splitting. Illumination of this...     

匀浆提取-超高效液相色谱-串联质谱法测定烟草中亚硝胺含量

提出了超高效液相色谱-串联质谱法测定烟草中N-亚硝基降烟碱(NNN)、N-亚硝基新烟草碱(NAT)、N-亚硝基假木贼碱(NAB)和4-甲基亚硝基吡啶基丁酮(NNK)等4种亚硝胺含量的方法。烟草样品经0.1mol.L-1乙酸铵溶液匀浆提取,离心分离取上清液过Waters AcquityUPLC BEH C18色谱柱(2.1mm×100mm,1.7μm)分离,以乙腈和0.01mol.L-1乙酸铵溶液按不同体积混合作流动相梯度洗脱。串联质谱测定中采用电喷雾离子源正离子模式和多反应监测模式检测,同位素内标法定量。NNK、NNN、NAB和NAT的检出限(3s)分别为0.06,0.17,0.15,0.053μg.L-1。方法的加标回收率在92.1%～104%之间;日内和日间相对标准偏差(n=7)分别为2.7%～3.3%和3.5%～4.2%。     

C5a受体拮抗剂W-54011的合成

以7-甲氧基-1-萘满酮为原料,经Wittig反应、去甲基化、烯醇互变和Jones氧化反应等制得关键中间体7-甲氧基-1,2,3,4-四氢化萘-1-羧酸(4); 4-异丙基苯胺和4-(二甲基胺基)苯甲醛经过还原胺化反应得(E)-4-{[(4-异丙基苯基)亚胺基]甲基}-N,N-二甲基苯胺(6); 4转化为相应的酰氯后与6反应合成N-[4-(二甲基氨基)苄基]-N-(4-异丙基苯基)-7-甲氧基-1,2,3,4-四氢化萘-1-甲酰胺(W-54011),总收率24%,其结构经¹H NMR, ¹³C NMR和HR-MS（ESI）表征。      

光学共振增强的表面铯激活银纳米结构光阴极

金属光阴极因其超短脉冲发射和运行寿命长的特性从而具有重要应用价值,但是较高的功函数和较强的电子散射使其需要采用高能量紫外光子激发且光电发射量子效率极低.本文利用Mie散射共振效应增强银纳米颗粒中的局域光学态密度,提升光吸收率和电子的输运效率,并利用激活层降低银的功函数,从而增强光阴极在可见光区的量子效率.采用时域有限差分方法分析银纳米球阵列的光学共振特性,采用磁控溅射和退火工艺在银/氧化锡铟复合衬底上制备银纳米球,紧接着在其表面沉积制备铯激活层,最后在高真空腔体中测试光电发射量子效率.实验结果表明平均粒径150 nm的银纳米球光阴极在425 nm波长的量子效率超过0.35%,为相同激活条件下银薄膜光阴极的12倍,峰值波长与理论计算的Mie共振波长相符合.     

DISCUSSION ON THE APPLICATION OF NUMERICAL EXPERIMENT IN EXPERIMENTAL TEACHING OF FLUID MECHANICS

为强化学生对流体力学课程理论知识及实验教学环节的掌握,本文针对传统实验教学过程中受限于硬件设施、模型等问题,将数值模拟技术与流体力学实验教学相结合。以伯努利实验为例,应用数值模拟软件进行物理建模、网格划分、变参数数值模拟等实验内容,通过压力云图、流线等模拟结果对能量转换特性进行了分析,增强了学生对流体力学理论知识及相关参数的物理意义、变化特征等的理解,使学生在实验中产生强烈的“参与感”,有效地提高了教学水平和教学质量。