The unimolecular chemistry of [1,2-propanediol]+˙: a rationale in terms of hydrogen-bridged radical cations

By combining results from a variety of mass spectrometric techniques (metastatle ion, collisional activation, collision-induced dissociative ionization, neutralization–reionization spectrometry and appearance energy measurements) and the classical method of isotopic labelling, a unified mechanism is proposed for the complex unimolecular chemistry of ionized 1,2-propanediol. The key intermediates involved are the stable hydrogen-bridged radical cations [CH₂?C(H)? H…?O…?O(H)CH₃]⁺˙, which were generated independently from [4-methoxy, 1-butanol]⁺˙ (loss of C₂H₄) and [1-methoxyglycerol]⁺˙ (loss of CH₂O), [CH₃? C?O…?H…?O(H)CH₃]⁺˙ and the related ion-dipole complex [CH₂?C(OH)CH₃/H₂O]⁺˙. The latter species serves as the precursor for the loss of CH³˙ and in this reaction the same non-ergodic behaviour is observed as in the loss of CH³˙ from the ionized enol of acetone.     

烷基锂分子中化学键的 ab initio 研究

本文用6-13G基函对3-12G基优化构型进行单点ab initio (从头计算法) 计算, 并根据轨道的组合系数、电荷密度图和键强参数等详尽地分析了烷基锂分子的成键情况。烷基锂的易挥发、易聚合、聚合物易溶于烃类溶剂中等物理、化学性质主要是其C－Li键具有显著的共价性缘故。由于烷基锂的C-Li键比C－H和C－C键的强度要小,故C-Li键易于断裂,使烷基锂表现有高的化学反应活性。     

Synthesis and H-NMR complexation studies of alkalimetal bithioxanthylidene crown ether complexes

Two synthetic routes to a novel class of sterically overcrowded alkenes, bithioxanthylidene crown ethers 1, are described. The ¹H spin-lattice relaxation times (T₁) of the crown ethers as well as those of the corresponding complexes with Li⁺, Na⁺, K⁺, Rb⁺ and Cs⁺ in CDCl₃ were measured and the results were interpreted in terms of complexation affinities.     

Restriction of Intramolecular Motion(RIM): Investigating AIE Mechanism from Experimental and Theoretical Studies

Mechanistic studies promote scientific development from phenomena to theories.Aggregation-induced emission(AIE),as an unusual photophysical phenomenon,builds the bridge between molecular science and aggregate mesoscience.With the twenty-year development of AIE,restriction of intramolecular motion(RIM)has been verified as the working mechanism of AIE effect.In this review,these mechanistic works about RIM are summarized from experimental and theoretical perspectives.Thereinto,the experimental studies are introduced from three parts:external rigidification,structural modification and structural characterization.In the theoretical part,calculations on the low-frequency motion of AIEgens have been performed to prove the RIM mechanism.By virtue of the theoretical calculations,some new mechanisms are proposed to supplement the RIM,such as restriction of access to conical intersection,suppression of Kasha transition,restriction of access to dark state,etc.It is foreseeable that the RIM mechanism will unify the photophysical theories for both molecules and aggregates,and inspire more progress in aggregate science.     

Montmorillonite KSF-Catalyzed Synthesis of 2,2′-(Arylmethylene)bis(3-hydroxy-5,5-dimethylcyclohex-2-en-1-ones) for the Functionalization of MCM-41 Silica Nanoparticles

Russian Journal of Organic Chemistry - A green protocol has been developed for the preparation of 2,2′-(arylmethylene)bis(3-hydroxy-5,5-dimethylcyclohex-2-en-1-ones) following the...     

Cu-Doped ZnO Nanoparticles for Non-Enzymatic Glucose Sensing

Copper-doped zinc oxide nanoparticles (NPs) Cu_xZn_1−xO (x = 0, 0.01, 0.02, 0.03, and 0.04) were synthesized via a sol-gel process and used as an active electrode material to fabricate a non-enzymatic electrochemical sensor for the detection of glucose. Their structure, composition, and chemical properties were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) and Raman spectroscopies, and zeta potential measurements. The electrochemical characterization of the sensors was studied using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). Cu doping was shown to improve the electrocatalytic activity for the oxidation of glucose, which resulted from the accelerated electron transfer and greatly improved electrochemical conductivity. The experimental conditions for the detection of glucose were optimized: a linear dependence between the glucose concentration and current intensity was established in the range from 1 nM to 100 μM with a limit of detection of 0.7 nM. The proposed sensor exhibited high selectivity for glucose in the presence of various interfering species. The developed sensor was also successfully tested for the detection of glucose in human serum samples.     

镍基甲烷化催化剂中的助剂作用 Ⅱ重稀土氧化物添加剂的结构效应和电子效应

应用ＢＥＴ、气相色谱、红外光谱、竞争加氢反应和ＸＰＳ等方法,在以前工作的基础上继续考察了Ｙ２Ｏ３、Ｓｍ２Ｏ３、Ｅｕ２Ｏ３、Ｇｄ２Ｏ３、Ｔｂ４Ｏ７、Ｄｙ２Ｏ３、Ｅｒ２Ｏ３、Ｔｍ２Ｏ３、Ｙｂ２Ｏ３作为添加剂,对镍在γ－Ａｌ２Ｏ３表面的分散度、甲烷化活性、ＣＯ在镍上的吸附态及表面镍原子的电子状态的影响．结果表明,稀土氧化物添加剂不仅明显地提高了金属镍的分散度和甲烷化活性,还直接地影响表面镍原子的电子状态．对不同稀土氧化物,这些效应各异．作者认为,利用稀土氧化物添加剂调节表面镍原子的电子状态,可能成为改进甲烷化催化剂活性的一个有效途径．     

H4GeMo12-nWnO40·mH2O（n=0, 9, 11, 12)和N-甲基吡咯烷酮电荷转移盐的合成、表征和非线性光学性质研究

由Ｈ４ＧｅＭｏ１２－ｎＷｎＯ４０·ｍ Ｈ２Ｏ（ｎ＝ ０, ９, １１, １２）和Ｎ－甲基吡咯烷酮合成,随后在ＣＨ３ＣＮ 和水中结晶,制成了一系列分子组成为［ＮＭＰＨ］４ＧｅＭｏ１２－ｎＷｎＯ４０·ＣＨ３ＣＮ的电荷转移化合物。并用元素分析、红外光谱、电子光谱进行了表征。结果表明在该系列化合物中, Ｎ－甲基吡咯烷酮通过Ｎ原子与酸中的质子结合成阳离子而与阴离子成盐;固体中阴离子和阳离子之间存在强的相互作用;化合物在光照下发生分子内电荷转移, 导致阳离子的氧化和阴离子的还原;ＥＳＲ结果表明阴离子还原反应处于单电子阶段; 非线性光学性质研究表明, 随着化合物分子内钨取代数的增多, 化合物倍频效应增强,三阶非线性系数增大     

不同添加物和制备方式对Al2O3热稳定性的影响

通过水溶液成胶和丙三醇络事助成胶制备了不同的结构的γ－Ａｌ２Ｏ３,研究了Ｌａ,Ｓｉ,Ｂａ以及Ｌａ,Ｓｉ和Ｌａ,Ｂａ双组分改性对它们结构热稳定的作用,讨论了改性元素的引入方式及硅铝比的影响。结果表明,丙三醇络合助成胶能明显提高Ａｌ２Ｏ３的比表面积和孔径,并能显著改善Ａｌ２Ｏ３的热稳定性。