两种由萘二酰亚胺衍生物构建的配位聚合物的合成、结构和光致变色性能

具有可逆颜色变化和适当变色寿命的光致变色材料对于无墨水和可擦除打印技术十分重要。我们将1,4,5,8-萘四羧酸二酐与甲硫氨酸结合,设计了一种基于1,4,5,8-萘二酰胺(NDI)的桥联有机配体(H2ncm),并以Zn^(2+)和H2ncm为原料,通过溶剂热反应合成了2种配位聚合物。化合物[Zn(ncm)(H_(2)O)_(4)]·2DMF(1)包含1个Zn^(2+)、1个ncm^(2-)配体、4个配位水分子和2个DMF分子。Zn^(2+)处于八面体的配位环境中,并通过ncm^(2-)配体连接形成链状结构。化合物[Zn_(2)(ncm)2(H_(2)O)_(4)](2)包含2个Zn^(2+)、2个ncm^(2-)配体和4个配位水分子。2个Zn^(2+)原子通过2个羧基桥联形成双核结构,并进一步通过ncm^(2-)配体连接形成二维层结构。2显示出从黄色到深棕色的光致变色现象。这种光诱导产生的颜色可以稳定至少3周,但在70℃加热时在5 min内即可恢复本来的颜色。我们证明了这种光致变色是源于光照射下NDI·自由基的产生。

STABLE PHOTOINDUCED RADICAL ACCUMULATION ON POLYPROPYLVIOLOGEN-RESIN COMPLEXES

The Photochemical properties of polyplxipylviologen (PPrV) - canon exchangeable resin complexes were studied. The color of these complexes changed toblue when irradiated by a mercury lamp. UV and ESR studies indicate that anefficient viologen medical accumulation occurs in PPrV -basin complexes. Anexplanation for the stable photoinduced radical accumulation is proposed.

Effect of ethanol addition on flame characteristics of waste oil biodiesel

Biodiesel is a kind of clean and renewable energy. The effect of ethanol addition on the flame characteristics of waste oil biodiesel is studied by using OH-PLIF technique from the perspective of OH radical evolution. Ethanol addition leads to the appearance of diffusion flame reaction interface ahead of schedule and shortens the diffusion flame height. The experimental results show a linear correlation between the flame height and the fuel flow rate for a given fuel and oxidant. The same conclusion is drawn from the theoretical analysis of the approximate model. In addition. ethanol addition makes the average OH signal intensity of flame at different fuel flow rate tend to be consistent and the fuel flow rate enlarge where the flame field shows the strongest oxidation performance. Average OH signal intensity begins to weaken at larger fuel flow rate, which indicates that fuel flow rate of fuels blended with ethanol can change in larger range and does not significantly affect the uniformity of combustion.

Intermediaries and Targets of the Oxidative Stress Induced by Natural Sunlight in Escherichia coil

The lethal effect produced by sunlight in bacteria depends on the photodynamic action of the ultraviolet component of the radiation. Neither the reactive oxygen species involved nor the targets for damage have been certainly identified, and the aim of this study was to address these issues. During exposures to natural sunlight, photo-protection provided by nitrogen sparging was compared with which provided by the addition of L-histidine （an efficient scavenger for hydroxyl radical and singlet oxygen） or mannitol （an hydroxyl radical scavenger which reacts poorly with singlet oxygen） to the irradiation medium. Both scavengers reproduced for the most part the effect of oxygen depletion, indicating that damage depends mainly on hydroxyl radical generation. Survival of irradiated bacteria decreased considerably when they were cultured using a substrate unsuitable for fermentation, suggesting that respiration impairment is a key factor in cell killing. This observation is in keeping with the notion that the respiratory chain is the main target for the action of sunlight in Escherichia coli.

微反应器技术在聚合中的应用研究进展

微反应器因其优良的传热、传质性能在聚合反应中的研究方兴未艾。与传统釜式聚合相比,微反应器聚合能够更好地调控聚合物分子量分布,提高聚合反应速率,控制聚合物分子结构和产物形貌。本文综述了微反应器技术在配位聚合、开环聚合和光诱导可控自由基聚合中的研究进展,并简要介绍了微反应器聚合技术的放大实验。最后,对微反应器技术在聚合物合成中的发展方向提出展望。

The cycloaddition reaction using visible light photoredox catalysis

In recent years, visible light photoredox catalysis has emerged as an important research area in synthesis. In this review, we describe the recent progress in the visible light induced cycloaddition reactions, including [2+2], [3+2], [4+2] and [2+2+2] cycloadditions, for the construction of four-, five- or six-membered cycles and polycycles. Furthermore, the mechanisms for these transformations are also discussed, in which the formation of the radicals is initiated by a visible light photoredox catalysis process.

Tadpole-shaped polymers based on UV-induced strain promoted azide-alkyne cycloaddition reaction

In the present study, we synthesized well-defined tadpole-shaped polystyrene(PS) via the combination of atom transfer radical polymerization(ATRP) and UV-induced strain promoted azide-alkyne cycloaddtion(SPAAC) reaction. A di-bromo ATRP initiator(Br-ini-Br) containing cyclopropenone-masked dibenzocyclooctyne group was used to prepare the linear PS with a cyclopropenone-masked dibenzocyclooctyne in the middle of the chain and bromo groups at both ends(Br-PS-Br). Then we used the single electron transfer-nitroxide radical coupling(SET-NRC) reaction to transfer the bromo end groups to azide groups(N_3-PS-N_3). After UV irradiation, the dibenzocyclooctyne group was quantitatively released, and intramolecularly reacted with alternative azide end group to produce the tadpole-shaped PS based on SPAAC reaction.

Swirl diffusion flame control by the plasma swirler

In this paper, the design of plasma swirler is presented in detail. The experiments were carded out to verify the feasibility of using plasma swirler to control diffusion flame. The plasma swider consists of multiple electrodes with staggered arrangement on both sides of combustor＇s expansion section. The plasma swirler can enhance combustion stability through ionizing the air to produce active free radical and promoting the swirling air. In the experiments, the flame response to the plasma swider was examined with OH distribution by planar laser induced fluorescence （PLIF）. The experimental results showed that the flame reaction zone was broadened with the increase of the plasma exciting, and this demonstrated that the plasma swirler could be used to control diffusion flame. The design of plasma swirler is feasible.