Synthesis of some chiral liquid crystals and study of the effect of intramolecular hydrogen bonding on the phase behaviour

The synthesis of three new series of chiral Schiff's bases containing benzilideneaniline and 2-hydroxybenzilideneaniline moieties as mesogenic cores is presented. Differential scanning calorimetry, optical polarizing microscopy and X-ray diffraction measurements were used to study the phase transition temperatures and behaviour. The results reveal that most of these materials show chiral smectic mesomorphism.     

三十烷醇在GA_3影响水稻幼苗生长和生理性状中的增效作用

微量三十烷醇（ＴＲＩＡ）与ＧＡ３配合使用，比ＧＡ３单独使用能明显地促进幼苗生长和增加幼苗干物质积累．同时还增强了ＧＡ３对幼叶中叶绿素含量、可溶性蛋白质含量、呼吸速率、细胞膜透性和过氧化物酶活性的影响．ＧＡ３＋ＴＲＩＡ与ＧＡ３处理相比，促进幼叶内源ＧＡ３水平提高，稳定保持内源ＺＴ于一定水平，ＴＲＩＡ在ＧＡ３低浓度时降低ＩＡＡ水平，在高浓度时则提高ＩＡＡ水平．作者认为ＴＲＩＡ可作为ＧＡ３处理时的增效剂．     

Hydrogenation of benzaldehyde and cinnamaldehyde in compressed CO2 medium with a Pt/C catalyst: a study on molecular interactions and pressure effects

The hydrogenation of benzaldehyde and cinnamaldehyde has been studied with a 5% Pt/C catalyst in compressed CO(2). The effect of CO(2) pressure on the total conversion was found to be different between the two aldehydes. The total conversion of benzaldehyde merely decreases with increasing CO(2) pressure, while that of cinnamaldehyde shows a maximum at a certain pressure. High-pressure FTIR measurements indicate the existence of interactions of CO(2) with the aldehydes. The absorption of nu(C=O) red-shifts at increasing CO(2) pressure, and this red-shift is more significant for cinnamaldehyde than for benzaldehyde, indicating that the C=O bond of the former becomes more reactive than the latter. The difference in the mode of interactions of CO(2) with these aldehydes has also been indicated by changes of nu(C=O) of CO(2). Thus, the conversion of benzaldehyde will decrease with increasing CO(2) pressure because of a simple dilution by introducing a larger quantity of CO(2). For cinnamaldehyde, the conversion will increase at low pressures because of increasing interactions with CO(2) molecules (increasing the reactivity of the C=O bond) but decrease at high pressures because of the simple dilution effect, similar to the case of benzaldehyde. The dense CO(2) molecules are not likely to change the catalytic activity of supported Pt particles, which was previously suggested from optical absorption of supported fine metal (Au) particles in a compressed CO(2) medium.     

A pH-sensitive controlled dual-drug release from meso-macroporous silica/multilayer-polyelectrolytes coated SBA-15 composites

A novel dual-drug delivery system based on mesoporous-macroporous silica/polyelectrolytes-SBA-15 has been synthesized. The structure and composition of these materials were characterized by powder X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and N₂ adsorption–desorption measurements. In this system, water-soluble metformin hydrochloride and fat-soluble ibuprofen were used as model drugs to study the controlled release behavior. The pH-controlled release of individual drugs was obtained by the primary release of metformin hydrochloride from polyelectrolytes-SBA-15 in acid condition and the predominant release of ibuprofen from MMC in alkaline environment. The results show that the polyelectrolytes-SBA-15/mesoporous-macroporous silica can be used as dual-drug release system and the individual drug can be controlled release with the change of pH value of the environment.     

Revisit of a series of ICT fluorophores: skeletal characterization,structural modification,and spectroscopic behavior

We have revisited the synthesis of a series of ICT fluorophores, which were reported to have a core structure of 8-oxo-8H-acenaphtho[1,2-b]pyrrol-9-carbonitrile. However, based on the 2D NMR and X-ray diffraction analysis, their core structure was corrected as 1-oxo-1H-phenalene-2,3-dicarbonitrile (1). Compound 1 shows a highly electron-deficient nature and can easily undergo oxidative S_NAr^H reaction on the naphthyl ring to produce a series of novel ICT fluorophores. The regioselectivity of this substitution reaction was studied by introduction of representative nucleophiles. Moreover, due to the strong rigidity and efficient ICT nature, the obtained fluorescent dyes display very good spectroscopic properties even in an aqueous environment.     

钼酸根阴离子在增强聚苯胺包覆的镍钴层状氢氧化物的电容和析氧行为中的关键作用

理论容量大且过电位低的层状氢氧化物(LDHs)是极有前景的超级电容电池和析氧反应的电极材料;然而,体相LDHs的低电导率和活性位点不足增加了电极的内阻,降低了电极容量和产氧效率.本文采用两步法制备了聚苯胺包覆的MoO42?插层的镍钴层状双金属氢氧化物复合电极(M-LDH@PANI).随着LDH中MoO42?含量的增加,针状的LDH微球逐渐演化为具有较高比表面积的片状M-LDH微球,这为整个电极提供了更多的电化学位点.此外,非晶态的聚苯胺包覆提高了复合电极的电导率.在引入适量MoO42?插层离子时,M-LDH@PANI表现出显著强化的储能和催化性能.所获得的M-LDH@PANI-0.5在析氧反应中表现出优越的电催化活性(10 mA cm?2时的过电位为266 mV),作为超级电容电池电极则具有864.8 C g?1的高容量.采用M-LDH@PANI-0.5作为正极及以活性炭作为负极组装的超级电容电池在功率密度为8,300.0 W kg?1时能量密度为44.6 Wh kg?1,且具有优异的循环稳定性(10000次循环后保留83.9％的初始容量).本文为LDH基材料的阴离子插层改性增强材料性能的机理提供了一个非传统的解释.在上述研究基础上,采用射线衍射(XRD)、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、高分辨透射电镜(HRTEM)和比表面积测试(BET)等手段对样品进行了深入表征.XRD结果表明,MoO42?插层的LDH材料的层间晶面(003)的峰随着MoO42?含量的增加而逐渐消失,这是由于晶面间距越大越容易受到晶粒细化的影响,间距大的晶格更容易受到破坏,导致晶格的展宽和弱化,从而间接证明MoO42?的成功插层.SEM、HRTEM和BET测试结果表明,MoO42?的含量对材料的形貌和比表面积具有重大影响.利用XPS对样品的价态进行了研究,发现随着MoO42?含量的增加,Co和Ni的价态没有明显变化.电化学测试结果表明,电极的储能和催化性能随MoO42?含量的增加而先增加后减小.利用理论计算分析了MoO42?在LDH中的插层行为,发现少量的MoO42?有利于扩大LDH的层间间距,而过量的MoO42?则会与LDH的H原子结合,从而与电解液中的OH?竞争,导致复合电极的电化学性能下降.此外,MoO42?插层的片状微球能有效调节材料的去质子化能,大大加速电极表面的氧化还原反应.因此,MoO42?插层能够显著强化LDH基材料的超级电容电池电极和OER催化剂电化学性能.     

Stretchable Perovskite Solar Cells with Recoverable Performance

Perovskite solar cells (PSCs) are a promising photovoltaic technology for stretchable applications because of their flexible, light‐weight, and low‐cost characteristics. However, the fragility of crystals and poor crystallinity of perovskite on stretchable substrates results in performance loss. In fact, grain boundary defects are the “Achilles’ heel” of optoelectronic and mechanical stability. We incorporate a self‐healing polyurethane (s‐PU) with dynamic oxime–carbamate bonds as a scaffold into the perovskite films, which simultaneously enhances crystallinity and passivates the grain boundary of the perovskite films. The stretchable PSCs with s‐PU deliver a stabilized efficiency of 19.15 % with negligible hysteresis, which is comparable to the performance on rigid substrates. The PSCs can maintain over 90 % of their initial efficiency after 3000 hours in air because of their self‐encapsulating structure. Importantly, the self‐healing function of the s‐PU scaffold was verified in situ. The s‐PU can release mechanical stress and repair cracks at the grain boundary on multiple levels. The devices recover 88 % of their original efficiency after 1000 cycles at 20 % stretch. We believe that this ingenious growth strategy for crystalline semiconductors will facilitate development of flexible and stretchable electronics.     

Analysis of hybrid donor layer in organic solar cells based on SubPc and rubrene

In this paper, photovoltaic characteristics of ITO/PEDOT:PSS/SubPc:Rubrene (mixed ratio R by weight)/C₆₀/Bphen/Ag organic solar cells (OSCs) are analyzed in detail. The intrinsic properties of a SubPc:rubrene doped layer on device performance were discussed based on theoretical analysis of the experimental OSCs. The ratio R was 0, 0.25, 0.5, and 0.75,1, respectively. The results showed that when R was 0.75 performing the best, which owned the highest short circuit current (J _sc ) 6.61 mA/cm² and highest power conversion efficiency (PCE) 2.44%, the FF was 41% and the open circuit current (V _oc ) was 0.905 V. The suitable HOMO level, absorption capacity, carrier transport ability and exciton diffusion length (L _D ) of organic material are very important for the performance of the device.     

Heck coupling reaction of iodobenzene and styrene using supercritical water in the absence of a catalyst

Heck coupling reaction of iodobenzene and styrene proceeds rapidly and selectively in supercritical water even without any catalyst in the presence of base. Both the choice of base and the reaction conditions had a significant effect on the conversion and the selectivity of the coupling products. The addition of a relatively mild base such as potassium acetate facilitated the cross-coupling reaction, while the hydrolysis of phenyl halide was favored in the presence of a strong base. The conversion and the yields of coupling products increased with increasing temperature, reaching a maximum at 650 K near the critical temperature of water, and then decreased as the temperature was further increased. Water density had a significant influence on the reaction rate, showing nearly 30% augmentation with a slight increase in density from 0.45 to 0.56 g cm(-3), but had less effect on the product selectivity. Two possibilities of the role of water responsible for the noncatalytic Heck coupling reaction in supercritical water, that is, ion and water-catalyzed mechanisms have been considered.