Synthesis and ~(183)W NMR Characterization of α-K_7GaW_(11)(TiO_2)O_(39)·11H_2O Heteropolyanion

In recent years, the research of peroxy polyoxometalates (POMs) has attracted increasing attention because of the two reasons. First, peroxy POMs are more active as oxygenation catalysts in some oxygen transfer reactions1~5. Second, recent research from our group and others has established that peroxy POMs are more active antiviral agents and less toxic both in vitro and in vivo than the parent metal-free POMs6. In order to entirely understand the properties and activities of peroxy POMs…     

Direct Electrochemistry of Hemoglobin in Layer-by-layer {PDDA/Hb}_n Films Assembled on Pyrolytic Graphite Electrodes

The principle of alternate adsorption can be used to design and control specific molecular architectures1. Protein-polyion layer-by-layer assembly opens a possibility of organizing proteins with specific molecular architectural plan1 and studying redox proteins with electrochemical methods2. Recently, we reported electrochemistry of layer-by-layer {PSS/Mb}n films grown on PG electrodes1. In this work, layer-by-layer {PDDA/Hb}n films were fabricated on PG electrodes. Electrochemistry and …     

Synthesis, Structure of a Symmetrically Substituted Stilbene with Strong Two-photon Absorption and Up-converted Blue Fluorescence

Symmetric substituted stilbenes have significantly potential application such as fluorescence microscopy, two-photon photodynamic therapy, optical power limiting, and three-dimensional storage1-2. These dyes have strong tendency of symmetric intra-molecular change transfer under the excited state. As a result, they usually exhibit large two-photon absorptivity (TPA), in the meanwhile emit strong up-converted fluorescence. On the other hand, their solutions generally display linear transmis…     

Chitosan-supported Borohydride Reducing Agent

Borohydride exchange resin (BER) a useful reducing reagent has been used in reduction of some carbonyl compounds and acyl halides1. When BER combines with a transition metal catalyst, it can reduce C=C double bonds2, halides2, nitro compounds3, cyano, diazo3 and azide compounds4. The support of BER is the synthetic macromolecule polystyrene. Here, we used chitosan as the support of borohydride. As known, chitosan is a renewable and abundant natural polysaccharide. Scheme 1 Preparat…     

A Concise Approach to the Synthesis of Carnosic Acid Type Diterpenes

AIDS has seriously affected human being's health and about 13.9 million people have been killed by AIDS in the world. So far, A. Paris et al1 found that Carnosic acid and its analogs posses inhibitory effect on HIV-1 protease and HIV virus replication activity. In order to clarify the structure-active relationship of this kind of compounds, a concise approach was designed, which is a convergent synthesis. Best to our knowledge, it is the first successful convergent route in total synthes…     

Synthesis and Characterization of (E)-5-[2-(N-hexylcarbazolyl)vinyl] furan Derivatives with Acceptor Groups

Organic second-order nonlinear optical (NLO) materials have been extensively studied for their potential application involving telecommunications, optical information process and storage1. It has been found that the molecular hyperpolarizability of the NLO chromophores varys dramatically depending upon the donor-acceptor abilities as well as the nature of the conjugated bridge.Carbazole molecule has an isoelectronic structure of diphenylamine, and thus the introduction of electron acceptor (…     

The Aggregates in LB Films of Schiff base Aluminium (III) Complex

Metal complexes, which are composed of metal ions and amphiphile ligands, show some structural peculiarities in Langmuir-Blodgett (LB) films. In the past studies, the metal complexes were mainly composed of the transitional metal ions1,2. The metal ions in IA, IIA and IIIA were seldom mentioned. Further more, the aluminium element is at the position where the typical metal elements transit to the typical non-metal elements in the periodic table of elements and study on the properties of …     

Effect of Reaction Media on Photoreaction of Provitamin D_3

IntroductionThe photochemistry of provitamin D3 (Pro) has been studied extensively in many years1-4. As shown in Scheme 11, irradiation of provitamin D3 in organic solvents results in its photoisomerization to previtamin D3 (Pre). Previtamin D3 can be thermally transferred into vitamin D3 (VD3), which is of commercial interests. However, previtamin D3 also undergoes the photochemical back reaction leading to the regeneration of provitamin D3 and the photoisomerization resulting in the und…     

Polymorphic Behavior of Syndiotactic Polypropylene Induced by Heat Treatment

The polymorphic behavior of syndiotactic polypropylene (s-PP) crystallized from the melt under different conditions was investigated by means of WAXD and DSC. The isothermal melt crystallization of s-PP proceeded in form I at tc≥ 110℃ and in form Ⅱ at tc≤110 ℃ s-PP crystallized nonisothermally from the melt was the mixture of forms and . With increasing the cooling rate (a), the content of form increased, and the content of form decreased. On heating, at 10 K/min, of quenched s-PP, it crystallized in form at t≤70 , continuing heating resulted in form form transition, which was an endothermal process.     

Water Dissociation Phenomena on a Bipolar Membrane──Current-voltage Curve in Relation with IonicTransport and Limiting Current Density

The water dissociation mechanism on a bipolar membrane under the electrical field was investigated and characterized in terms of ionic transport and limiting current density. It is considered that the depletion layer exists at the junction of a bipolar membrane, which is coincided with the viewpoint of the most literatures, but we also consider that the thickness and conductivity of this layer is not only related with the increase of the applied voltage but also with the limiting current density. Below the limiting current density, the thickness of the depletion layer keeps a constant and the conductivity decreases with the increase of the applied voltage; while above the limiting current density, the depletion thickness will increase with the increase of the applied voltage and the conductivity keeps a very low constant. Based on the data reported in the literatures and independent determinations, the limiting current density was calculated and the experimental curves Ⅰ-Ⅴ in the two directions were com