Search results for "medium"
showing 10 items of 3746 documents
Ferromagnetic copper(II)–copper(II) interaction in a single chlorido and dicyanamido bridged mixed–valence copper(I/II) 2D polymer generated by in si…
2015
A mixed-valence 2-D Cu(I/II) complex, [{Cu(II)(dmen)(μ-Cl)(μ1,5-dca)}{Cu(I)(μ1,5-dca)}]n (1) (dmen = N,N-dimethylethylenediamine, dca = dicyanamide = [N(CN)2]−), has been synthesized by in situ partial reduction of Cu(II) to Cu(I) using benzoin (2-hydroxy-1,2-di(phenyl)ethanone) as reductant. Complex 1 was characterized by spectroscopic techniques, single crystal X-ray diffraction, and low temperature magnetic measurements. Structural investigation reveals that 1 represents a mixed-valence 2-D coordination polymer formed by parallel 1-D [Cu(II)(dmen)(Cl)Cu(I)(μ1,5-dca)2]n chains running along the b axis, where chloride bridges Cu(II) ions of adjacent polymers through long connections (2.840…
Methylation as an effective way to generate SOD-activity in copper complexes of scorpiand-like azamacrocyclic receptors
2018
Abstract Methylation of the secondary amine groups of a scorpiand-type ligand consisting of a pyridine spacer connected through methylene groups to a tris(2-aminomethyl) unit with the pendant arm further functionalised with a 3-pyridine unit leads to a ligand whose Cu(II) complex exhibits threefold enhanced SOD activity with respect to the non-methylated ligand. Potentiometric studies indicate the formation of [CuL] 2+ species with a stability three orders of magnitude lower than that formed with the related non-methylated ligand. Kinetic studies indicate that methylation of the secondary nitrogens causes a deceleration of both the complex formation and the acid-induced dissociation of the …
Divergent route to the preparation of hybrid Pt–Fe 2,4,6-Tris(4-ethynyl)phenyl-1,3,5-triazine metallodendrimers for nonlinear optics
2013
Abstract: The synthesis strategy for the preparation of novel platinum acetylide homometallic and heterobimetallic dendrimers (containing Fe as the other metal fragment) based on a 2,4,6-tris(4-ethynyl)phenyl-1,3,5-triazine core (3) is reported. All the dendrimer generations (G0G2) were synthesized under copper-free conditions following a divergent route. The G0-Pt dendrimer (4) was synthesized using the 1,3,5-triazine core (3) and cis-[Pt(PEt3)2Cl2] with a molar ratio of 1/4. The advantage of the current method is that different dendrimers can be prepared by following the same procedure with only changes in the molar ratios of the reactants involved. For instance, when 3 reacts with 4 in a…
s-Block metal scorpionates – A new sodium hydrido-tris(3,5-dimethyl-1-pyrazolyl)borate salt showing an unusual core stabilized by bridging and termin…
2020
Abstract Dissolution of [(μ-Me2CO)3(NaTp*)2] (1) (Tp* = hydrido-tris(3,5-dimethyl-1-pyrazolyl)borate) in DMSO at room temperature leads to the growth of colourless crystals characterized as the new salt [Na2Tp*(μ-Me2SO)3(Me2SO)3] [NaTp* 2] (2). 2 crystallized in the trigonal space group R3 with Z = 3, a = 14.1227(2) Å, b = 14.1227(10) Å, c = 33.9685(2) Å, and V = 5867.35(17) Å3. Interestingly, anion and cation of 2 both contain the Tp* ligand. Moreover, the cationic moiety highlights an unusual sodium atom hexacoordinated by six DMSO molecules acting as O-bonded ligands. Three of which exhibit a bridging coordination mode and three are in terminal position. To the best of our knowledge, the…
Crystal structure of μ-oxido-1,1′κ2 O:O-bis{tetra-μ-oxido-1:2κ2 O:O;1:3κ2 O:O;2:3κ4 O:O-tris[1,2,3(η5)-pentamethylcyclopentadienyl]-trianglo-tri…
2015
The title polynuclear organometallic titanium(IV) oxide, [{Ti3(η5-C5Me5)3(μ-O)4}2(μ-O)], exhibits two Ti3O4 cores bridged by an O atom located on a twofold axis. All metal centers present the typical three-legged piano-stool coordination environment, where one site is occupied by a pentamethylcyclopentadienyl ligand linked in an η5-coordination fashion, while three bridging O atoms fill the other three sites.
The response of Trissolcus basalis to footprint contact kairomones from Nezara viridula females is mediated by leaf epicuticular waxes.
2009
Chemical footprints left behind by true bugs are perceived as contact kairomones by scelionid egg parasitoids. Female wasps encountering a contaminated artificial substrate display a characteristic arrestment posture, holding the body motionless and antennating the surface. In the system Nezara viridula (L.) and its egg parasitoid Trissolcus basalis (Wollaston), previous studies have shown that the kairomone mediating such behavior is part of N. viridula's cuticular hydrocarbons (CHC) and furthermore that the wasp's ability to discriminate host male and female footprints is mainly based on the presence/absence of nonadecane (nC(19)). In this study, the effect of epicuticular waxes of leaves…
Experimental Survey on Dry Asphalt Rubber Concrete for Sub-ballast Layers
2012
This paper presents the results of an experimental survey on the potential application of DARC (dry asphalt rubber concrete) in rail superstructure, within sub-ballast layers by measuring its damping and mechanical properties. Based on the environmental friendly point of view the DARC has the significant advantage as the backfill material of sub-ballast layer because the rubber comes from the waste tires of truck and its usage can results a significant recycling of non-biodegradable wastes. After a preliminary mix-design of several DARCs, with different rubber content that confirmed by using the Marshall test, the stiffness modulus and damping ratio both of a standard bituminous mixture and…
Application of textile fibres from tire recycling in asphalt mixtures
2022
The tire rubber obtained from end-of-life car and truck tires has been successfully recycled, among other applications, in the asphalt industry by providing a mean to get asphalt mixtures with superior performance. Textile fibres are another component derived from tire recycling typically disposed of in landfills or used in energetic valorisation. This paper wants to re-ignite interest in this secondary product by evaluating its use as a valuable resource in asphalt mixtures. Indirect tensile tests, dynamic modulus, fatigue resistance, and permanent deformation tests were performed on a series of AC14 asphalt mixtures manufactured with two binders, namely 50/70 and 35/50 pen, using several …
Dioxomolybdenum(VI) and -tungsten(VI) complexes with tetradentate aminobis(phenol)s
2006
Abstract Aminobis(phenol) ligands (H2Ln) carrying either a dimethylamino, a pyridyl or a methoxy sidearm donor were used in the preparation of new tungsten and molybdenum complexes. Treatment of [W(eg)3] (eg = 1,2-ethanediolate dianion) with H2Ln under hydrolytic conditions in a CHCl3–MeOH mixture gave the cis-dioxotungsten(VI) complexes [WO2(Ln)] in good yields. The corresponding molybdenum complexes [MoO2(Ln)] were prepared from [MoO2(acac)2] and respective ligands. The solid-state structures of two molybdenum and one tungsten compounds were determined by single crystal X-ray diffraction, which revealed that the dianionic aminobis(phenolate) backbones of the ligands have coordinated to th…
From tungsten hexacarbonyl adsorption on TiO2(1 1 0) surface to supported tungsten oxide phases.
2008
Abstract Synchrotron-based photoemission spectroscopies were used to study the adsorption of tungsten hexacarbonyl on (1 1 0) TiO 2 surfaces: experiments using W4f and Ti2p intensities variations show that, at 140 K, the hexacarbonyl growth proceeds via a layer-by-layer mode. Moreover, it was evidenced using both core levels and valence band experiments that, after back to room temperature, W(CO) 6 desorbs without significant decomposition. However, low energy (500 eV) ion (Ar + ) irradiation can allow partial decomposition of tungsten hexacarbonyl molecules leading to sub-carbonyl tungsten molecules. The bonding of sub-carbonyl species to the TiO 2 surface was then stronger than the one of…