Polynaphthoxazines-Montmorillonite Nanocomposites: Synthesis and Characterization

Thermally resistant structural materials play a key role in the progress of the electronics and aerospace industries. Polybenzoxazine, a novel ring-opening phenolic resin, with superior properties such as no volatile emission when curing, near zero shrinkage and high mechanical performance, can be deemed as alternatives of traditional phenolics. Layered clays dispersed in a polymer matrix on nanoscale reinforced the thermal resistance and mechanical performance of the composite. The prepara…     

Dioxygen Affinity and Catalytic Performance of Bis-(furaldehyde) Schiff Bases Co(II) Complexes in Cyclohexene Oxidation

As mimetic oxygen carrier or oxidation catalyst, Schiff base cobalt complexes such as Co (II) salen have been widely studied1-4. However their high-price greatly limited their application. The synthesis of cheap furaldehyde Schiff bases and their complexes with Co (II), as well as the dioxygen affinity and biomimetic catalytic oxidation performance of these complexes are worth trying to study. In this paper, the saturated dioxygen uptake of cobalt complexes with different bis-(furaldehyd…     

Synthesis of 1-(3',4'-dihydroxyphenyl)-7-(4"-hydroxyphenyl)- 4hepten-3-one

Natural diarylheptanoids have significant bioactivities. Some of them are potent inhibitors against prostaglandin biosynthesizing enzyme (PG synthetase) and 5-lipoxygenase (LT synthetase)1-2. Compound 1 was firstly isolated from Alnus rubra bark3. So far its synthesis has not been reported yet. Herein, we report the synthesis of compound 1. Meantime, compound 24 was also obtianed as an intermediate. Compound 7 and 16 were converted to compound 10 and 18 respectively, because compound 1…     

On-Line Multichannel Raman Spectroscopic Detection System For Capillary Zone Electrophoresis

Detection and peak identification are key factors in developing CE (capillary electrophoresis) methodology. They have become hotspots for many reasons. The most obvious one lies in the revealing of unknown species in the application of CE to biological samples. CE-MS and CE-NMR have since been developed. CE-Raman spectroscopy was also reported1. As compared to the former two methods, the Raman spectroscopy method is highly attractive because it has the potential to provide high-informat…     

Enantiomeric Separation of Amino Alcohols by Ion-pair Chromatography

Many drugs or physiologically important compounds are chiral molecules and the optical isomers of them may differ in their pharmacological activities. In some instances differences in undesirable side-effects of these enantiomers are important. So the separation of chiral compounds is becoming increasingly important. Liquid chromatography (LC) is well known as an excellent method for separating and analyzing mixtures of stereoisomers. For resolving the ionic chiral compounds it is available t…     

A Novel Bimetallic Tetrahedron Cobalt Complex Promoting the Addition of Diethylzinc to Benzaldehyde

Asymmetric catalytic addition of dialkyzinc to aldehyde using chiral ligands has become one of the most active areas in asymmetric synthesis. In recent years, various chiral ligands have exhibited good results in promoting this asymmetric addition1, such asβ- amino alcohol and chiral amine which possess chiral carbon centers, chiral ((6-arene) chromium complexes2, derivatives of Ferrocene3, which possess planar chirality, and BINOL and NOBIN4. Further development of novel catalysts is sti…     

First Enantioselective Synthesis of (2R,3R)-and(2S,3S)-2-(4-hydroxyphenyl)-3-hydroxymethyl-1,4-benzodioxan-6-carbaldehyde

Numerous lignans containing 1,4-benzodioxane nucleus represent a class of natural products with cytotoxic and hepatoprotective activities1,2. Recently we have reported the racemic total synthesis of sinaiticin, a flavonolignan of the 1,4-benzodioxane type which was isolated from sinaiticum leaves found in sinai region of Egypt, using 2-(4-hydroxyphenyl)-3-hydroxymethyl-1,4-benzodioxan-6-carbaldehyde as the key interme-diate3,4. This species exhibits significant inhibitory activity against the …     

Active Oxygen Radical Scavenging Ability of Water-Soluble β-Alanine C_(60) Adducts

The bioactivity study of C60 and its relative derivatives is of considerable importance. Functional fullerenes have peculiar biological activities, such as enzymatic inhibition, anti-HIV activity, neuroprotection, antibacterial activity, DNA cleavage, and photodynamic therapy et al.1. Neuroprotective properties are based on the facts that functional fullerenes have antioxidant properties and high reactivity toward free radical2. Active oxygen radical in biological system mainly include…     

A New Monodisperse Reactive Resin with Active Groups on the Particle Surface

The cross-linked polymer beads with reactive groups as active supports have been widely used in many fields such as chromatographic separation, solid phase synthesis, catalytic reaction, ion exchange and adsorption etc. In resent years, the synthesis and application of monodisperse polymer beads with different structures have been rapidly developed1~4. It is obvious that this type of monosized resin as matrix of active supports will be even more advantageous in some applications. This paper pr…     

The Enantioselective Addition of Diethylzinc to Aldehydes Catalyzed by 2-Methylquinoline Derived Chiral Ligands

One of the most important and fundamental synthetic procedures for the establishment of a carbon-carbon bond stereoselectively is the enantioselective addition of organometallic reagents to aldehydes affording chiral secondary alcohols1. In this process, a frequently used method is to perform the reaction in the presence of a chiral ligand such as amino alcohol2. Here, we first report that two new chiral ligands3, which were readily available by the reaction of chiral ketone with lithiated 2-m…