Recent advances in the polymerisation of propylene

Since its discovery, the field of olefin polymerization using Ziegler-Natta catalysts has undergone rapid development both in terms of industrial catalysis as well as fundamental understanding of this polymerization process. This paper reviews some aspects of the recent developments with specific regard to propylene polymerizations. Presented at the Symposium on ’Polymer Science and Engineering during the Annual Meeting of the Academy, Nainital, October 1982     

Recent advances in the neodymium catalysed polymerisation of 1,3-dienes

The benefits of using a homogeneous neodymium-based catalyst for the industrial “high cis” polymerisation of 1,3-butadiene are underlined. Preformed homogeneous catalysts for the “high cis” polymerisation of 1,3-butadiene based on Nd(carboxylate)₃/diisobutylaluminium hydride/^tbutyl chloride have been examined. The effects of changing (a) the order of catalyst component addition, (b) the carboxylate component and (c) the halogen component, on catalyst homogeneity, activity and polymer characteristics have been examined.     

Recent advances in iridium-catalysed asymmetric hydrogenation of unfunctionalised olefins

In this account, the recent advances which have been made in asymmetric iridium-catalysed hydrogenation are reviewed. The first part focuses on our own studies of bicyclic pyridine–phosphinite ligands. These ligands have greatly enhanced the application range of asymmetric hydrogenation and, for the first time, have allowed highly enantioselective hydrogenation of simple, alkyl-substituted olefins and substituted furans. In the second part of this account, experimental and computational mechanistic studies are discussed. Whether the catalytic cycle proceeds via Ir(I)–Ir(III) intermediates or via Ir(III)–Ir(V) intermediates is still the subject of debate.     

Recent advances in asymmetric copper allylic oxidation of olefins

This review deals with the recent advances in asymmetric copper allylic oxidation of olefins. An exhaustive analysis of the results has been realized showing the limitation of the different asymmetric catalytic systems used.     

Recent advances in the homogeneous palladium-catalyzed aerobic oxidation of alcohols

The use of palladium catalysts for the oxidation of alcohols to aldehydes and ketones in the presence of various types of reoxidants is well known. Recently, the advantages of using molecular oxygen as the oxidant in the Pd-catalyzed oxidation of alcohols have been explored. The aim of this review is to provide an overview on the most important homogeneous palladium-catalyzed aerobic oxidation of alcohols without a co-catalyst during last decade until the end of 2007.     

Asymmetric reductive ring-opening of bicyclic olefins catalyzed by palladium and nickel complexes

[reaction: see text] Asymmetric reductive ring opening of oxa- and azabenzonorbornadienes with organic acids and zinc powder under mild conditions catalyzed by Ni(binap)Cl(2) or Pd(binap)I(2) produces the corresponding 1,2-dihydronaphth-1-ols in good to excellent yields with high enantioselectivity.     

Ring-opening polymerisation of rac-lactide mediated by cationic zinc complexes featuring P-stereogenic bisphosphinimine ligands

The diastereomerically pure P-stereogenic bis(phosphinimine) ligands 4,6-(ArN[double bond, length as m-dash]PMePh)(2)dbf [Ar = 4-isopropylphenyl (Pipp): rac-4, meso-4; Ar = 2,6-diisopropylphenyl (Dipp): rac-4a; dbf = dibenzofuran] were synthesised and complexed to zinc using a protonation-alkane elimination strategy. The cationic alkylzinc complexes thus obtained, RZn[4,6-(ArN[double bond, length as m-dash]PMePh)(2)dbf][B(Ar')(4)] [Ar = Pipp, Ar' = C(6)H(3)(CF(3))(2): rac-6 (R = Et), meso-6 (R = Et), rac-7 (R = Me) meso-7 (R = Me); Ar = Dipp: rac-6a (R = Et, Ar' = C(6)H(3)(CF(3))(2)), rac-6b (R = Et, Ar' = C(6)F(5))] were investigated for their competency as initiators for the ring-opening polymerisation of rac-lactide. The formation of polylactide was achieved under relatively mild conditions (40 °C, 2-4 h) and the microstructures of the resulting polymers exhibited a slight heterotactic bias [polymer tacticity (P(r)) = 0.51-0.63].     

Recent advances in hydrogen-bonded hexameric encapsulation complexes

Basic research in the chemistry of hexameric resorcin[4]arenes and pyrogallol[4]arenes during the last decade is reviewed. Applications of NMR methods to determine solution structures, host guest properties and exchange dynamics are discussed. The scientific issue is the behavior of molecules in small spaces; the challenge is to translate this information to practical applications in, say, catalysis or transport.     

Heterogeneous catalysts for the controlled ring-opening polymerisation of rac-lactide and homogeneous silsesquioxane model complexes

In this communication we report, for the first time, the ring-opening polymerisation in the melt of rac-lactide with heterogeneous catalysts. Homogeneous model systems based on silsesquioxanes have been prepared for comparison.     

Highly stereoselective ring-opening addition of terminal acetylenes to bicyclic olefins catalyzed by nickel complexes

[reaction: see text] Treatment of 7-oxa- and 7-azabenzonorbornadienes with terminal acetylenes in the presence of Ni(dppe)Cl2, ZnCl2, and Zn powder in toluene at 90 degrees C afforded the corresponding cis-2-alkynyl-1,2-dihydronaphthalene derivatives in moderate to excellent yields with remarkably high stereoselectivity.     

Recent advances of organometallic complexes in emerging photovoltaics

Organometallic complexes (OMCs) consisting of organic and metal active moieties have shown immense potential for application in solar cells. The diverse structure, rich porosity, and unique charge centers of OMCs enable them to be functional in solar cells. In this review, we introduced four types of OMCs, such as crown organometallic complexes, β-diketone metal complexes, cyclometallic complexes, and main chain metal-containing polymers, providing an in-depth analysis of the structure-performance relationship. OMCs could serve as active or interlayer materials in a variety of solar cell systems such as organic solar cells, perovskite solar cells, and dye-sensitized solar cells, especially some metals to improve the photoelectric performance of the device as dopants. In the end, perspectives on the opportunities and challenges of OMCs are given.     

非血红素铁、锰配合物催化烯烃不对称环氧化反应研究进展

手性环氧化物是重要的有机反应中间体.金属氧化酶催化的氧化反应通常具有高效、高选择性、反应条件温和和绿色的特点,模拟其中的非血红素铁加氧酶设计合成一系列手性四氮铁锰配合物催化烯烃不对称环氧化反应成为获得高产率、高对映选择性的手性环氧化物的一个重要方法.本文综述了近年来非血红素手性四氮铁锰配合物催化烯烃不对称环氧化反应的研究进展及相应的机理研究.     

Recent advances in CAN mediated reactions in organic synthesis

The emergence of CAN as a versatile one-electron oxidant is attested by the wide range of reactions that can be executed by this reagent. The literature on CAN chemistry is updated in the present review while highlighting the reactions that make CAN an exceptional reagent.     

Chromium imine and amine complexes as homogeneous catalysts for the trimerisation and polymerisation of ethylene

Cr(III) complexes of tridendate imine and amine ligands with N, P, O, S donor atoms 1 and 2 have been prepared and tested as catalysts in the oligomerisation and polymerisation of ethylene giving excellent selectivity towards 1-hexene and polymerisation to polyethylene when activated with cocatalysts. X-ray structure analyses of the precatalysts 1a-c, 1i, and 2b are investigated. The metal-ligand binding in 1a and 1b is nearly the same, which leads to similar catalytic activities of these precatalysts.     

Recent advances in the isolation and reactivity of organogold complexes

Homogeneous gold catalysis has been one of the most active research fields in organic chemistry for more than a decade, and it has been also among the most efficient methodologies for forming carbon-carbon or carbon-heteroatom bonds. Recently, a number of organogold intermediates were isolated from stoichiometric reactions, which helps to better understand the mechanisms. Meanwhile, the reactivity of organogold compounds has been attracting the attention of organic chemists in the field. This tutorial review collects the most recent advances in the isolation and reactivity of organogold compounds that may help to open new directions in homogenous gold catalysis.     

Recent advances in the sensitized luminescence of organic europium complexes

In this paper, recent advances in the synthesis, mechanism of sensitized emission, and luminescent properties of organic lanthanide complexes are reviewed. Stress is put on the progress in the development of organic europium complexes and their nanoparticles with excellent visible-light-sensitized and two-photon-sensitized Eu^III luminescence properties. These are of increasing importance because bioanalysis or bioimaging techniques based on such labeled materials will combine the advantages of high sensitivity, high signal-to-noise ratio, deep penetration, and low photodamage to biological samples. In addition, the application of long-wavelength-sensitized luminescence of organic lanthanide complexes and their nanoparticles in bioimaging is discussed.