The synthesis and photophysical properties of novel cationic tetra pyridiloxy substituted aluminium, silicon and titanium phthalocyanines in water

This work reports on the synthesis, characterisation and photophysical properties of new unquaternized β-2,(3)-tetra-(2 pyridiloxy) aluminium(III) (3a), silicon(IV) (3b), titanium(IV) (3c) phthalocyanines and their water-soluble quaternized counterparts, 4a, 4b and 4c, respectively. The water-soluble silicon(IV) (4b) and titanium(IV) (4c) phthalocyanine derivatives were found to be aggregated in aqueous media but were partially or fully disaggregated in the presence of a surfactant Cremophor^® EL (CEL). The photophysical properties of aggregated complexes were investigated both in the presence of CEL and in pH 11 alone. Low triplet and fluorescence yield were obtained in pH 11 but an improvement was achieved upon addition of CEL for the aggregated complexes. The unquaternized silicon(IV) phthalocyanine complex (3b) gave the highest triplet quantum yield of 0.77 in DMF followed by its quaternized derivative (4b) with triplet yield of 0.73 in pH 11 plus CEL. The highest triplet lifetime of 220 μs was obtained for 4b in the presence of CEL. Higher fluorescence yields of 0.23 were obtained for quaternized water-soluble aluminium(III) phthalocyanine derivative (4a) in the presence of CEL.     

Improved synthesis and crystal structure of tetrakis(acetonitrile)(η-1,5-cyclooctadiene)ruthenium(II) bis[tetrafluoroborate(1−)]

An improved, one-step synthesis of [Ru^II(1,5-COD)(CH₃CN)₄]²⁺ as the BF₄⁻ salt has been accomplished in 51% yield, an approximately 75% higher yield than the three-step literature synthesis of the corresponding PF₆⁻ salt. The improved synthesis consists of (i) grinding the insoluble [RuCl₂(1,5-COD)]_x precursor to increase the reaction rate and yield, (ii) treating the resultant [RuCl₂(1,5-COD)]_x with 2Ag⁺BF₄⁻ in refluxing acetonitrile with excess 1,5-COD present to inhibit 1,5-COD loss in the product and, most importantly, (iii) following the reaction directly by ¹H-NMR spectrometry which revealed that the substitution reaction of the Ru(II), d⁶ precursor is, as expected, quite slow and requires ca. 120 h. The [Ru(1,5-COD)(CH₃CN)₄][BF₄]₂ product was characterized by ¹H, ¹³C, and ¹⁹F-NMR, elemental analysis, and single-crystal X-ray crystallography. Problems in commercial Ru and F analyses are also addressed since this issue has been inadequately treated in the existing literature.     

OH‐Initiated Photooxidations of 1‐Pentene and 2‐Methyl‐2‐propen‐1‐ol: Mechanism and Yields of the Primary Carbonyl Products

The products of the gas‐phase reactions of OH radicals with 1‐pentene and 2‐methyl‐2‐propen‐1‐ol (221MPO) at T=298±2 K and atmospheric pressure were investigated by using a 4500 L atmospheric simulation chamber that was built especially for this work. The molar yield of butyraldehyde was 0.74±0.12 mol for the reaction of 1‐pentene. This work provides the first product molar yield determination of formaldehyde (0.82±0.12 mol), 1‐hydroxypropan‐2‐one (0.84±0.13 mol), and methacrolein (0.078±0.012 mol) from the reaction of 221MPO with OH radicals. The mechanism of this reaction is discussed in relation to the experimental results. Additionally, taking into consideration the complex mechanism, the rate coefficients of the reactions of OH with formaldehyde, 1‐hydroxypropan‐2‐one, and methacrolein were derived at atmospheric pressure and T=298±2 K.; the obtained values were (8.9±1.6)×10^?12, (2.4±1.4)×10^?12, and (22.9±2.3)×10^?12 cm³ molecule^?1 s^?1, respectively.     

New One‐Pot Procedure for the Synthesis of 2‐Substituted Benzimidazoles

A highly selective synthesis of 2‐substituted benzimidazole derivatives from the reaction of o‐phenylendiamine derivatives and aromatic aldehydes in the presence of an organic salt, NH₄OAc, in absolute ethanol is presented. The products were obtained by evaporating the solvent followed by a simple recrystallization with excellent yields.     

New liquid crystals derived from thiophene connected to the 1,2,3-triazole heterocycle

In this work, six new compound derivatives from thiophene were synthesised. The three symmetrical compounds were synthesised containing two heterocyclic 1,2,3-triazole on each side of thiophene, 2,5-disubstituted and the three non-symmetrical compounds were synthesised containing alkyne groups as a spacer in replacing one of these heterocycles. The structural modifications were made by changing the number of alkoxy groups in order to understand the relation between structure and mesomorphic behaviour. Some of the compounds presented liquid crystalline properties, smectic and nematic mesophases. The non-symmetrical compounds allowed for a low emission in the blue region.     

替位杂质对低能Pt原子与Pt(111)表面相互作用影响的分子动力学模拟

采用嵌入原子方法的原子间相互作用势，通过分子动力学方法模拟了低能Pt原子与Cu，Ag，Au，Ni，Pd替位掺杂Pt(111)表面的相互作用过程，系统研究了替位原子对表面吸附原子产额、溅射产额和空位缺陷产额的影响规律，分析了低能沉积过程中沉积原子与基体表面的相互作用机理以及替位原子的作用及其影响规律.研究结果显示：替位原子的存在不仅影响着沉积能量较低时的表面吸附原子的产额与空间分布，而且对沉积能量较高时的低能表面溅射过程和基体表面空位的形成产生重要影响.替位原子导致的表面吸附原子产额、表面原子溅射以及空位形 关键词： 分子动力学 低能粒子 替位掺杂 表面原子产额 溅射 空位     

Sputter yields in diamond bombarded by ultra low energy ions

Artificial diamond is an ideal material for high power, high voltage electronic devices, and for engineering use in extreme environments. Diamond process development requires parallel development in characterization techniques such as ultra low energy SIMS (uleSIMS), especially in the ability to depth profile for impurities and dopants at high depth resolution.As a contribution to the background knowledge required, we have measured the sputter yields of single crystal high pressure high temperature (HPHT) diamond using O₂⁺, Cs⁺ and Ar⁺ primary ions in the energy range 300 eV to 2 keV. We compare these with yields for silicon and GaAs. We show that the erosion rates with oxygen are ∼10 times what would be expected from ballistic processes and essentially energy independent in the measured range. This result agrees with the anomalously high sputter yield observed in the ion etching context. Conversely, positive ion yields for elements such as boron are very low in comparison with silicon. This points to a reactive ion etching process liberating CO or CO₂ rather than sputtering as the principal erosion process.This is both problematic and beneficial for SIMS analysis. Oxygen can be used to reach buried structures in diamond efficiently, and the effects of the near-normal incidence beam are planarizing as they are in silicon. Conversely, since positive ion yields are low, alternative probes or strategies must be found for high sensitivity profiling of electropositive elements.     

L-shell ionization of atoms and their subsequent decay by radiative and non-radiative transitions

The study of the ionization of atoms resulting in vacancies in their inner shells and the subsequent decay of the atomic-vacancy states by x-ray and Auger transitions continue to be an active area of interest. A rapid survey of the theoretical efforts to calculate the transition probabilities involvingL-subshells in the high-Z atoms is presented. A complete review of theL ₁-subshell yields for single-vacancy atomic states obtained by various experimental techniques is included. The production of multiple vacancies in theL shell and the role of the spectator vacancies in the decay process is discussed. A detailed case study of determining experimentally the number of multiple vacancies produced, and the x-ray fluorescence yields during ionization by heavy-ion bombardment is presented. It is established that the effect of spectator vacancies is to increase the x-ray fluorescence yields substantially.     

结构温度场和温度应力场的有限元分析

讨论用有限元分析温度对结构刚度和强度的影响。从热传导问题的基本方程出发，求解稳态和瞬态温度场所用的有限元一般格式，进而在瞬态不均匀温度场状态下，可将其影响转换成相应的等效节点温度载荷。采用一般有限元法可求得计算在此类载荷作用下结构的变形和应力场。本文所列算例结果合理，表明本文推荐的方法适用于工程分析。     

CdS量子点的一步法合成及量子产率

以油酸为配体,十八烯为溶剂,采用一步法合成了CdS量子点,研究了反应温度、反应时间和Cd/S的摩尔比对量子点光谱性能的影响.X射线衍射(XRD)和高分辨透射电镜(HRTEM)测试结果表明,所获得的CdS量子点为立方闪锌矿结构,且尺寸分布均一,结晶度高,其较强的带边发光、尖锐的紫外吸收峰以及狭窄的荧光发射峰进一步表明量子...