The POSS side chain epoxy nanocomposite: Synthesis and thermal properties

The IPI‐POSS‐modified epoxy resin (IPEP) was prepared from isocyanato‐propyldinethylsilyl‐isobutyl‐POSS (IPI‐POSS) and diglycidyl ether of bisphenol A epoxy resin. The steric hindrance of the IPEP bulky POSS side chain improved the curing activation energies. The POSS particles sizes were about 2–3 nm and dispersed uniformly. At lower IPEP concentration (POSS < 12 wt %), the glass transition temperatures (T_gs) of the IPEP nanocomposites increased from 118 to 170 °C. The char yield increased from 15 to 20 wt %, and the LOI values increased from 22 to 28. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 643–652, 2010     

Synthesis and characterization of a novel paramagnetic macromolecular complex [Gd(TTDASQ-protamine)

Adenocarcinomas in rats and humans frequently contain perivascular, degranulating mast cells that release heparin. Protamine is a low-molecular weight, cationic polypeptide that binds to heparin and neutralizes its anticoagulant properties. A novel magnetic resonance imaging (MRI) contrast agent containing protamine was synthesized. TTDASQ, the derivative of TTDA (3,6,10-tri(carboxymethyl)-3,6,10-triazadodecanedioic acid), was also synthesized and the kinetic stability of [Gd(TTDASQ)]- chelate containing phosphate buffer and ZnCl2 to measure the relaxation rate (R1) at 20 MHz was studied by transmetallation with Zn(II). The water-exchange rate (k(ex)298) of [Gd(TTDASQ)]- is 6.4 x 10(6) s(-1) at 25.0 +/- 0.1 degrees C which was obtained from the reduced 17O relaxation rates (1/T(1r) and 1/T(2r)) and chemical shift (omega(r)) of H(2)17O, and it is compared with that previously reported for the other gadolinium(III) complex, [Gd(DO3ASQ)]. The binding affinity assay showed that the (TTDASQ)3-pro19 has higher activity toward heparin. On the other hand, the effect of heparin on the relaxivity of the [Gd(TTDASQ)3-pro19] conjugate shows the binding strength (K(A)) is 7669 dm3 mol(-1) at pH 7.4 and the relaxivity (r(b)1) of the [Gd(TTDASQ)3-pro19]-heparin adduct is 30.9 dm3 mmol(-1) s(-1).     

Novel sesquiterpenoids from the Formosan soft coral Paralemnalia thyrsoides

Three sesquiterpenoids with unprecedented skeletons, paralemnanone (1), isoparalemnanone (2), and paralemnanol (3), were isolated from the Formosan soft coral Paralemnalia thyrsoides. Their structures were elucidated by extensive spectroscopic analysis, and the structure of 1 was further confirmed by X-ray crystallographic analysis. The absolute stereochemistries of 1-3 were established by application of the Mosher’s method on 2.     

Electrooxidation Enables Selective Dehydrogenative [4+2] Annulation between Indole Derivatives

Dearomative annulation of indoles has emerged as a powerful tool for the preparation of polycyclic indoline‐based alkaloids. Compared with well‐established methods towards five‐membered‐ring‐fused indolines, the six‐membered‐ring‐fused indolines are rarely accessed under thermal conditions. Herein, a dearomative [4+2] annulation between different indoles is developed through an electrochemical pathway. This transformation offers a remarkably regio‐ and stereoselective route to highly functionalized pyrimido[5,4‐b]indoles under oxidant‐ and metal‐free conditions. Notably, this electrochemical approach maintains excellent functional‐group tolerance and can be extended as a modification tactic for pharmaceutical research. Preliminary mechanism studies indicate that the electrooxidation annulation proceeds through radical–radical cross‐coupling between an indole radical cation and an N‐centered radical generated in situ.     

Nanofiltration membranes synthesized from hyperbranched polyethyleneimine

Four nanofiltration membranes, two negatively and two positively charged, were fabricated by interfacial polymerization. Three different amines, ethylenediamine (EDA), diethylenetriamine (DETA), and hyperbranched polyethyleneimine (PEI) were selected to react with two acyl chlorides, trimesoyl chloride (TMC) and terephthaloyl chloride (TPC). The two membranes containing hyperbranched PEI, PEI/TPC and PEI/TMC, are positively charged at the operational pH. But the other two membranes, EDA/TMC and DETA/TMC, are negatively charged. It is found that the two PEI membranes own special rejection characters during nanofiltration. The PEI/TPC membrane has a similar pore size to the EDA/TMC membrane but owns simultaneously the higher salt rejection and permeation flux. The PEI/TMC has a pore size as large as 1.5 nm and still has a higher NaCl rejection than the EDA/TMC membrane of which the pore size as small as 0.43 nm. We consider that the special rejection characters are derived from the special structure of PEI. The hyperbranched structure allows some of the charged amine groups drifting inside the pores and interacting with the ions in the pathway. The drifting amines increase salt rejection but have little effect on water permeation. It implies that a high flux and high rejection membrane for desalting can be obtained by attaching freely rotating charged groups.     

Excavatoids A-D, new polyoxygenated briaranes from the octocoral Briareum excavatum

Three polyoxygenated briaranes, including two new compounds, excavatoids A (1) and B (2), and a known metabolite, briaexcavatin I (3), were isolated from the cultured octocoral Briareum excavatum. Moreover, the wild type B. excavatum, collected off southern Taiwan coast, yielded two new 5,6-epoxybriaranes, excavatoids C (4) and D (5). The structures of new compounds 1, 2, 4, and 5 were determined by spectroscopic methods and the structure of 1 was further confirmed by X-ray diffraction data analysis. The X-ray structure for briaexcavatin I (3) was also reported for the first time. Excavatoid A (1) is the first briarane which possesses six hydroxy groups and a 17-methoxy group. Excavatoid C (4) is the first 12,13-secobriarane which possesses a novel pentacyclic skeleton with an ?-lactone. Excavatoid D (5) displayed moderate inhibitory effects on superoxide anion generation and elastase release by human neutrophils.     

Efficient epoxidation of alkenes with aqueous hydrogen peroxide catalyzed by methyltrioxorhenium and 3-cyanopyridine

The epoxidation of alkenes with 30% aqueous hydrogen peroxide is catalyzed efficiently by methyltrioxorhenium (MTO) in the presence of pyridine additives. The addition of 1-10 mol % of 3-cyanopyridine increases the system's efficiency for terminal and trans-disubstituted alkenes resulting in high isolated yields of the corresponding epoxides. The system allows for epoxidation of alkenes with various functional groups. Alkenes leading to acid-sensitive products are efficiently epoxidized using a mixture of pyridine and 3-cyanopyridine as additives. This method is operationally very simple and uses an environmentally benign oxidant. The effects of different pyridine additives on the alkene conversion and the catalyst lifetime are discussed.     

TiO2 and SnO2@TiO2 hollow spheres assembled from anatase TiO2 nanosheets with enhanced lithium storage properties

TiO(2) and SnO(2)@TiO(2) hollow spheres assembled from anatase TiO(2) nanosheets with exposed (001) high-energy facets are constructed via a templating approach, and the as-prepared samples exhibit enhanced lithium storage properties.     

Steroid and cembranoids from the Dongsha atoll soft coral Lobophytum sarcophytoides

A novel sterol, sarcophytosterol (1), and four new cembranoids, sarcophytolins A-D (2-5), have been isolated from the soft coral Lobophytum sarcophytoides along with four known metabolites 6-9. The relative structures of new metabolites were elucidated on the basis of extensive spectroscopic analyses and X-ray diffraction analysis of 1, and the absolute configurations of 1 and 5 were determined by Mosher’s method and CD spectrum, respectively. Compound 1 is a steroid possessing an unusual (20R,23R,24R)-23,24-dimethyl-20-hydroxy side chain. Compounds 3, 6, 8, and 9 were shown to exhibit cytotoxicity toward a limited panel of cancer cell lines. Furthermore, while 1 could effectively enhance the expression of the pro-inflammatory iNOS protein in LPS-stimulated RAW264.7 macrophage cells, compounds 2, 3, 5-7 and 9 were found to effectively inhibit the accumulation of the pro-inflammatory of iNOS.     

Synergistical assembly of multiwalled carbon nanotubes/polyaniline network for dye‐sensitized solar cells

In this study, an aniline (ANI) solution containing well‐dispersed multiwall carbon nanotubes (CNTs) has been prepared. With an aim of improving the dispersability of CNTs in ANI monomer, we synthesize CNTs/ANI complexes using a reflux technique which can be electrochemically polymerized to form well‐dispersed CNTs/polyaniline (PANI) films. The refluxed CNTs/ANI solution can be used to prepare high porous CNTs/PANI network via an electrochemical polymerization for applying as counter electrodes in dye‐sensitized solar cells. Compared with the pristine PANI, the multiwalled CNTs/PANI network shows more porous morphology and higher electrocatalytic activity, resulting in the acceleration of the reaction (triiodide (I^3?) to iodide (I^?)) of the redox electrolyte. The enhancement of the electrocatalytic activity is attributed to the interactions between multiwalled CNTs and PANI, promoting the quinoid ring structure and thus enhancing the conductivity of the polymer chains. The device, assembled with multiwalled CNTs/PANI network as counter electrodes, delivers 7.67% power conversion efficiency, which is comparable to 7.43% of that with Pt. Copyright © 2014 John Wiley & Sons, Ltd.