The innovation of polyolefin with unique architecture, composition and topology continues to inspire polymer chemists. An exciting recent direction in the field is design new catalysts based on late-transition metals. In this review, we highlight developments rationally designing metal for olefin polymerization. examples described review showcase power well-defined late-metal tailored synthesis, which may usher a era industry.

Better by design: Exploitation of the macrocyclic architecture a cyclophane-based ligand provides new highly active catalysts with improved thermal stability for ethylene polymerization. The strategic positioning metal center at core is key to observed high activity and stability, molecular weight polyethylene (see picture; red: Pd, green: Cl, blue: N, gray: C).

Polar olefins were copolymerized with ethylene using a cyclophane-based palladium(II) α-diimine catalyst. The incorporation levels of both methyl acrylate and tert-butyl are unusually high compared to what is obtained the corresponding acyclic Mechanistic studies by low-temperature NMR spectroscopy revealed that differences between insertion barriers for MA (ΔΔG⧧) similar cyclophane catalysts. equilibration comonomers, fast on experimental time scales catalyst, was too slow be measured These...

ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication the EditorNEXTLiving Polymerization of α-Olefins at Elevated Temperatures Catalyzed by a Highly Active and Robust Cyclophane-Based Nickel CatalystDrexel H. Camacho Zhibin GuanView Author Information Department Chemistry, University California, Irvine, California 92697-2025 Cite this: Macromolecules 2005, 38, 7, 2544–2546Publication Date (Web):March 1, 2005Publication History Received7 January 2005Revised12 February...

Degradation of polysaccharides to afford low-molecular-weight oligosaccharides have been shown produce new bioactivities that are not present in the starting material. The simplicity ultrasonic treatment degradation a polysaccharide, such as κ-carrageenan, offers practical advantage producing degraded products with lower molecular weight may interesting potential activities. This study embarked on investigating effects weights and structural changes κ-carrageenan under varying conditions....

Palladium-catalyzed addition of alcohol pronucleophiles 1 to alkylidenecyclopropane derivatives 2 afforded the corresponding allylic ethers 3 in excellent moderate yields. Catalyst optimization indicated Pd(PPh3)4−P(o-tolyl)3 combination as best system among all catalysts tested. Intramolecular reaction also proceeded smoothly. A plausible mechanism for this catalytic was proposed.

Hydrophilic gelling kit consisting of carrageenan-stabilized silver nanoparticles (AgNPs) is described herein as a selective probe for the colorimetric detection Hg2+. Spherical AgNPs with surface plasmon resonance (SPR) at 430 nm and TEM size less than 100 were synthesized using κ-carrageenan to give dark brown mixture (Carr-AgNP) that used directly reaction various metal ions. The only color Carr-AgNP was found fade concentration Hg2+ increases until turns white. It can detect ≥350 ppm...

Hydroalkoxylations proceed by a different path than transition metal catalyzed hydrostannations and hydrosilylations. In the reaction of methylenecyclopropanes 1 with alcohols 2 in presence Pd0, distal bond cyclopropane ring is cleaved, allyl ether 3 formed selectively. R1=n-C7H15, PhCH2CH2; R2=H, R3=PhCH2, CF3CH2, Et3Si, n-C4H9, etc.

Vorteile durch Design: Makrocyclische Cyclophanliganden erhöhen die thermische Stabilität von neuen Katalysatoren für Polymerisation Ethen zu Polyethylen mit hohem Molekulargewicht. Entscheidend hohe Aktivität und ist strategische Platzierung des Zentralmetalls im Kern der Cyclophanarchitektur (siehe Bild; Pd rot, Cl grün, N blau, C grau). Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2001/2004/z53226_s.pdf or from author. Please...

[structure: see text] Herein we describe an efficient synthesis of cyclophanes comprised intra-annular nitrogen functional groups through a template-promoted cyclization by ring-closing metathesis (RCM). The proceeds condensation meta-styryl anilines with acenaphthenequinone to form the templates, followed RCM Grubb's second-generation catalyst afford internal alpha-diimine functionality. Prolonged hydrogenation efficiently removes template provide macrocycle containing diamine

This work investigates the effect of sonication on brown and milled rice grains both waxy non-waxy varieties. We report herein microstructural analysis uncooked kernels under its textural properties. X-ray computed tomography results showed formation microporous surfaces creation cracks fissures. Sonication increased % porosity samples allowing for easy penetration water during cooking process promotes softer texture. Moreover, in resulted to decrease endogenous iron phosphorus contents but...

An efficient synthetic route to a novel macrocyclic aryl α-diimine ligand bearing C6 hydrocarbon bridges connecting the ortho positions is described. Pd(II) and Ni(II) complexes with new (10 14) were successfully synthesized characterized. The X-ray crystal structures of 10 14 show that exhibit coordination geometry similar their acyclic analogues alkyl do not introduce significant ring strain into complexes. preactivated complex 12 allyl nickel tested for ethylene polymerization. Potential...

Poly(3,4-ethylenedioxythiophene) (PEDOT)-κ-carregeenan polymer electrolyte blend was prepared and incorporated as the system in dye-sensitized solar cells (DSSC). Polymer blends with different κ-carrageenan concentrations molecular weights were investigated. It found that conductivity of increases higher concentration, lowers degraded κ-carregeenan. The a DSSC yielded cell efficiency (η) 0.421%.