cis-Dichlorido(1,3-dimesitylimidazolidin-2-yl­idene)(2-formyl­benzyl­idene-κ2 C,O)ruthenium diethyl ether solvate

The title compound, [RuCl2(C8H6O)(C21H26N2)]·C4H10O, contains a catalytically active ruthenium carbene complex of the ‘second-generation Grubbs/Hoveyda’ type with Ru in a square-pyramidal coordination, the apex of which is formed by the benzyl­idene carbene atom with Ru=C 1.827 (2) Å. The complex shows the uncommon cis, rather than the usual trans, arrangement of the two chloride ligands, with Ru—Cl bond lengths of 2.3548 (6) and 2.3600 (6) Å, and a Cl—Ru—Cl angle of 89.76 (2)°. This cis configuration is desirable for certain applications of ring-opening metathesis polymerization (ROMP) of strained cyclic olefins. The crystalline solid is a diethyl ether solvate, which is built up from a porous framework of Ru complexes held together by π–π stacking and C—H⋯Cl and C—H⋯O inter­actions. The disordered diethyl ether solvent mol­ecules are contained in two independent infinite channels, which extend parallel to the c axis at x,y = 0,0 and x,y = , and have solvent-accessible void volumes of 695 and 464 Å3 per unit cell

Singlet oxygen generation as a major cause for parasitic reactions during cycling of aprotic lithium-oxygen batteries

Non-aqueous metal–oxygen batteries depend critically on the reversible formation/decomposition of metal oxides on cycling. Irreversible parasitic reactions cause poor rechargeability, efficiency, and cycle life, and have predominantly been ascribed to the reactivity of reduced oxygen species with cell components. These species, however, cannot fully explain the side reactions. Herewe showthat singlet oxygen forms at the cathode of a lithium–oxygen cell during discharge and from the onset of charge, and accounts for the majority of parasitic reaction products. The amount increases during discharge, early stages of charge, and charging at higher voltages, and is enhanced by the presence of tracewater. Superoxide and peroxide appear to be involved in singlet oxygen generation. Singlet oxygen traps and quenchers can reduce parasitic reactions effectively. Awareness of the highly reactive singlet oxygen in non-aqueous metal–oxygen batteries gives a rationale for future research towards achieving highly reversible cell operation

Phosphorescent Organic Light-Emitting Devices: Working Principle and Iridium Based Emitter Materials

Even though organic light-emitting device (OLED) technology has evolved to a point where it is now an important competitor to liquid crystal displays (LCDs), further scientific efforts devoted to the design, engineering and fabrication of OLEDs are required for complete commercialization of this technology. Along these lines, the present work reviews the essentials of OLED technology putting special focus on the general working principle of single and multilayer OLEDs, fluorescent and phosphorescent emitter materials as well as transfer processes in host materials doped with phosphorescent dyes. Moreover, as a prototypical example of phosphorescent emitter materials, a brief discussion of homo- and heteroleptic iridium(III) complexes is enclosed concentrating on their synthesis, photophysical properties and approaches for realizing iridium based phosphorescent polymers

Nanocomposite foams from iron oxide stabilized dicyclopentadiene high internal phase emulsions

Nanocomposite polyHIPE foams with open-cellular morphology were obtained using nanoparticles ($γFe_2O_3/Fe_3O_4$), surfactant (Pluronic L121) or nanoparticle/surfactant stabilized dicyclopentadiene high internal phase emulsions (DCPD HIPEs). Upon curing, cavity sizes were found to vary drastically between 950 ± 360 µm down to 7 ±3 µm de- pending on the HIPE formulations. As-obtained nanocomposite polyHIPE foams were functionalized using elemental bromine in THF. Upon bromination the nanoparticles are moved from the cavities surfaces into the bulk phase of the polymer scaffold, which affects the inductive-heating capability of the magnetic nanocomposite foams decreasing it by the factor of 2.V tem strokovnem članku opisujem pripravo makroporoznih nanokompozitnih pen iz diciklopentadienskih HIP emulzij stabiliziranimi z $γFe_2O_3/Fe_3O_4$ nanodelci, t.i. Pickering emulzij in HIP emulzij stabiliziranimi s kombinacijo surfaktanta in nanodelcev. Tako pripravljene nanokompozitne pene smo primerjali s penami pripravljenimi iz HIP emulzij stabiliziranimi le s surfaktanti in ugotovili da se premer por spreminja in sicer od 7 ± 3 m do 950 ± 360 µm. V nadaljevanju smo nanokompozitne makroporzne pene funkcionalizirali z elementarnim bromom, ter raziskali vpliv bromiranja na samo lokacijo nanodelcev in sposobnost $γFe_2O_3/Fe_3O_4$ nanodelcev da ob prisotnosti zunanjega alternirajočega magnetnega polja proizvajajo toploto. V ta namen smo bromirano nanokompozitno peno izpostavili zunanjemu izmeničnemu magnetnem polju, ter ugotovili da se sposobnost segrevanje zmanjša za faktor 2

A Natural Rubber Waste Derived Surfactant for High Internal Phase Emulsion Templating of Poly(dicyclopentadiene)

The use of a surfactant derived from the degradation of natural rubber gloves via cross-metathesis with methyl acrylate and subsequent saponification of the ester group for the stabilization of water in dicyclopentadiene high internal phase emulsions is described. The versatility of the resulting high internal phase emulsion was demonstrated by polymerizing the continuous dicyclopentadiene phase via Ring-opening Metathesis Polymerization yielding macroporous poly(dicyclopentadiene) foams with a porosity of 82 %. The use of the ionic surfactant allows for the preparation of foams, which are resistant to absorb water. This property was hitherto not accessible with protocols involving the use of non-ionic surfactants commonly employed in emulsion templating of polymers.<br /

The Effects of Enhancing the Crosslinking Degree in High Internal Phase Emulsion Templated Poly(dicyclopentadiene) Cured by Ring-Opening Metathesis Polymerization by a Crosslinking Comonomer

The effect of enhancing the crosslinking degree in polyHIPEs made from dicyclopentadiene by additionally using a crosslinking comonomer is described. Foams of 80% porosity with 10-40 w% comonomer content in the continous phase are prepared and show similar porosities and morphological characteristics as foams prepared with dicyclopentadiene alone. Assessing the mechanical properties reveals that the ductility is decreasing while the stiffness of the samples is increasing with increasing comonomer content. The foams containing the crosslinking comonomer take up at least five fold mass of toluene therby swelling to at least 30 v%. Upon drying of the swollen specimens, their initial shap and porosity are recovered. This feature distinguishes them from polyHIPEs made from dicyclopentadiene only.<br /

Step-Growth Polymerisation of Alkyl Acrylates via Concomitant Oxa-Michael and Transesterification Reactions

Herein we propose an auto-tandem catalytic approach towards the preparation of poly(ester-ether)s from simple alkyl acrylates and diols. By combining oxa-Michael addition with transesterification the preparation of hydroxy functionalised acrylate monomers can be avoided.<br /

A theoretical view on the thermodynamic cis-trans equilibrium of dihalo ruthenium olefin metathesis (pre-)catalysts

This work was conducted to provide an overview on the position of the thermodynamic cis-trans equilibrium of 85 conventional and X-chelated alkylidene-ruthenium complexes (X=O, S, Se, N, P, Cl, I, Br). The reported energies (Delta E) were obtained through single-point calculations with M06 functional and TZVP basis set from BP86/SVP-optimized cis- and trans-dichloro geometries and using the polarizable continuum model to simulate the influence of the solvent. Dichloromethane and toluene were selected as examples for solvents with high and low dielectric constants. The obtained relative stabilities of the cis- and trans-dihalo derivatives of the respective alkylidene complexes will serve for a better explanation of their catalytic activity as has been disclosed herein with selected examples. [GRAPHICS