Octane Group Research Articles

Efficient and region-selective conversion of octanes to epoxides under ambient conditions: Performance of tri-copper catalyst, [Cu3I(L)]+1 (L=7-N-Etppz)

In this paper, is described the conversion of the octane group of hydrocarbons into industrially important epoxides using tri-copper catalyst, [Cu 3 I (L)] +1 (L=7-N-Etppz). The role of hydrogen peroxide as a sacrificial oxygen donor during catalytic conversion to epoxides has been investigated. The performance of the catalyst has been evaluated in terms of turnover numbers (TON) and turnover frequencies (TOF) reported in this article.

Small gold nanoparticles with narrow size distribution achieved in SBA-15 pores by using ionic silsesquioxane instead of thiol group as stabilizer and adhesion agent

Organofunctionalized SBA-15 was obtained using two organic precursors, mercaptopropyltrimethoxysilane and/or an ionic silsesquioxane that contains the 1,4-diazoniabicyclo[2.2.2]octane group. These materials were used as support for gold nanoparticles loading, aiming to study their ability as gold nanoparticle stabilizers and also as adhesion agents on SBA-15 pore surface. Different gold amounts were employed to synthesize gold nanoparticles inside of pores. The materials were studied by using elemental and thermogravimetric analyses, adsorption-desorption isotherms, X-ray diffraction, UV–Vis spectroscopy and transmission electron microscopy. From these techniques, it was possible to compare the behaviour of both organic groups and their performance aiming to obtain gold nanocatalyst supported on SBA-15. The use of ionic silsesquioxane leads to smaller and spherical gold nanoparticles with narrower size distribution, and as consequence, the material presents better performance as catalyst.

Polybenzimidazole-crosslinked poly(vinylbenzyl chloride) with quaternary 1,4-diazabicyclo (2.2.2) octane groups as high-performance anion exchange membrane for fuel cells

Development of anion exchange membrane (AEM) with high conductivity, good dimensional stability, desirable toughness and long life-time simultaneously is still a challenge for the practical application of AEM fuel cells. Herein, a novel AEM (denoted as PBI-c-PVBC/OH) is fabricated by applying polybenzimidazole (PBI) and 1,4-diazabicyclo (2.2.2) octane (DABCO) as the macromolecular crosslinker and quaternizing reagent for poly(vinylbenzyl chloride) (PVBC), respectively. With the aid of crosslinking by PBI, PBI-c-PVBC/OH exhibits good flexibility and strength both in dry and water-saturated state. Moreover, high hydroxide conductivity (>25 mS cm−1 at room temperature) and low swelling ratio (∼13%) is obtained, especially the swelling ratio nearly does not increase with temperature. The membrane is also advanced for the superior chemical stability in alkaline environment due to the stable polymer backbone and ionic conductive group (only one nitrogen atom in a DABCO molecule is quaternized). Furthermore, a peak power density of 230 mW cm−2 at 50 °C is obtained on the H2/O2 fuel cell using PBI-c-PVBC/OH, and the membrane presents high durability both in the constant current and continuous open circuit voltage testing. Therefore, it is considered that the PBI crosslinking together with DABCO quaternization can be regarded as a promising strategy in the development of AEM for fuel cells.

Synthesis and Solid-State Characterization of Self-Assembled Macrocyclic Molecular Rotors of Bis(dithiocarbamate) Ligands with Diorganotin(IV)

Two bis(dithiocarbamate) (bdtc) metallamacrocyclic compounds, 1 and 2, and the deuterated analogues 1-d8 and 1-d20 were readily prepared through self-assembly processes involving the corresponding secondary bis(diamines), with two equivalents each of CS2 and dimethyltin(IV) dichloride. Solid-state characterization using FTIR, PXRD, and TGA indicated that the solid phases of both macrocycles were amorphous solids. For compound 1, a crystalline phase could only be obtained in the form of a dichloromethane solvate; however, the corresponding crystal lattice was unstable and collapsed rapidly under ambient conditions. The bdtc ligands containing para-disubstituted phenylene (compound 1) and bicyclo[2.2.2]octane groups (compound 2) showed rotational motion within the macrocyclic assemblies in the solid state. For compound 1, the internal rotation of the phenylene groups was examined first by 13C NMR CPMAS spectroscopy using the 1-d20 derivative in which the hydrogen atoms of the pendant phenyl groups had been substituted with deuterium atoms and also by 2H NMR spin echo experiments using the 1-d8 derivative in which the rotating phenylene groups have been deuterated. Line shape analysis using a log-Gaussian distribution model indicated that the central phenylene rings experience fast 2-fold flip reorientations over the sp2–sp3 carbon atom axes, overcoming an activation energy of Ea = 10 kcal/mol with a preexponential factor A = 3.9 × 1014 s–1. For compound 2, the 13C CPMAS experiments suggested that the bicyclo[2.2.2]octane moieties also undergo fast internal dynamics, which is in agreement with the higher symmetry of these fragments when compared to the phenylene spacers.

1,4-Diazobicyclo(2,2,2)octane-modified multi-ammonium derivatives as ratiometric fluorescent sensors for lipopolysaccharide

A series of pyrene derivatives bearing multi-quaternary ammonium 1,4-diazobicyclo(2,2,2)octane groups were synthesised as ratiometric fluorescent sensors for lipopolysaccharide (LPS) in aqueous solution. Ratiometric changes in fluorescence spectra of the sensors were observed from the pyrene monomer–excimer conversion which is modulated by the supramolecular self-assembly between sensors and LPS. These sensors show high selectivity towards LPS with the detection limit down to tens of nanomolar levels. The interaction mechanism between the sensors and LPS was also discussed.

Surfactant-Based Dispersant for Multiwall Carbon Nanotubes to Prepare Ceramic Composites by a Sol–Gel Method

A dispersant for multiwall carbon nanotubes (MWCNTs) is proposed that fulfils the requirements of creating a uniform dispersion in the matrix and obtaining a good interface between CNTs and the matrix, and is soluble in generic nonpolar solvents. This dispersant is based on a long chain surfactant, called in this work dabcosil stearate, containing a stearate-based 18-carbon alkyl chain as an anion, and a silsesquioxane containing a bridged, positively charged 1,4-diazoniabicyclo[2.2.2]octane group. It provides not only a very good dispersion medium for the MWCNTs, but also a very good interface between MWCNTs and ceramic matrices, such as alumina and zirconia, prepared by the sol-gel method.

Modified 4-(dicyanomethylene)-2- tert-butyl-6-(1,1,7,7-tetra-methyljulolidyl-9-enyl)-4 H-pyran-containing red fluorescent emitters for efficient organic light-emitting diodes

Efficient red fluorescent compounds Red 1 and Red 2 based on bulky bicyclo[2,2,2]octane groups in the pyran moiety and tert-butyl or isopropyl group in the julolidine moiety of the 4-(dicyanomethylene)-2- tert-butyl-6-(1,1,7,7-tetra-methyljulolidyl-9-enyl)-4 H-pyran (DCJTB) skeleton were synthesized and characterized. As red-emitting dopants in an Alq 3 single-host emitting system, Red 1 and Red 2 exhibited improved color purity and enhanced luminous efficiency compared to DCJTB. Moreover, a device using Red 1 as a dopant in a rubrene–Alq 3 co-host emitting system exhibited improved electroluminescence performance with a luminous efficiency and power efficiency of 6.89 cd/A and 3.09 lm/W at 20 mA/cm 2, respectively, and CIE x,y coordinates of ( x = 0.64, y = 0.36) at 7.0 V, approaching saturated red emission.

Silica grafted with a silsesquioxane containing the positively charged 1,4-diazoniabicyclo[2.2.2]octane group used as adsorbent for anionic dye removal

The present study reports the development of an alternative adsorbent, based on silica modified with a water soluble silsesquioxane containing a double charged 1,4-diazoniabicyclo[2.2.2]octane, employed for removal of the dye brilliant yellow from aqueous solution. The dye removal ability of this adsorbent was determined by batch adsorption procedure. Effects such as pH value and adsorbent dosage on the adsorption capacity were studied. Four kinetic models were applied. The adsorption was best fitted to a fractionary-order kinetic model. The kinetic data were also adjusted to an intra-particle diffusion model resulting three linear regions, indicating that the adsorption kinetics follows multiple sorption rates. The equilibrium data were fitted to Langmuir, Freundlich, Sips and Redlich–Peterson isotherm models. The maximum adsorption capacity was 54 mg g − 1.

Discovery of 2-arylthieno[3,2-d]pyrimidines containing 8-oxa-3-azabi-cyclo[3.2.1]octane in the 4-position as potent inhibitors of mTOR with selectivity over PI3K

2-Aryl-4-morpholinothieno[3,2-d]pyrimidines are known PI3K inhibitors. This class of compounds also potently inhibited the homologous enzyme mTOR. Replacement of the morpholine group in these compounds with an 8-oxa-3-azabicyclo[3.2.1]octane group led to mTOR inhibitors with selectivity over PI3K. Optimization of the 2-aryl substituent led to the discovery of 2-(4-ureidophenyl)-thienopyrimidines as highly potent (IC(50) <1nM) mTOR inhibitors with excellent selectivity (up to >1000-fold) over PI3K and good potency in a cellular proliferation assay (IC(50) <50nM).

Brilliant yellow dye immobilized on silica and silica/titania based hybrid xerogels containing bridged positively charged 1,4-diazoniabicyclo[2.2.2]octane: Preparation, characterization and electrochemical properties study

Silica and silica/titania based hybrid xerogels containing the double charged 1,4-diazoniabicyclo[2.2.2]octane group bonded in a bridged way were obtained. The hybrids were characterized by infrared spectroscopy and CHN analyses for the identification and determination of organic content. N 2 adsorption–desorption isotherms and SEM were applied to study morphological and textural aspects. The hybrid materials presented anion-exchange properties that allowed their use as adsorbent for brilliant yellow anionic dye. These modified materials were used to prepare carbon paste electrodes for cyclic voltammetric measurements, where the brilliant yellow, for the first time, was applied as electroactive species. The pH solution has no effect on the anodic peak potential and anodic peak current in the values range between 2.0 and 7.0. The electrode response was invariant under various oxidation–reduction cycles showing that the system is chemically very stable. Considering that the presence of titanium oxide in the xerogel enhanced the conductivity, a carbon paste electrode of the (R 2dabco)BY/SiO 2/TiO 2 material was prepared to study the electrocatalytic oxidation of ascorbic acid by cyclic voltammetric and chronoamperometric techniques.

Octane-1,8-diylbis[3-ethyl-1H-1,2,4-triazol-5(4H)-one

The title compound, C16H28N6O2, has a centre of symmetry. There are two planar 1,2,4-triazole rings, connected by an octane group. The crystal structure is stabilized by C—H⋯N, C—H⋯O and N—H⋯O intermolecular hydrogen bonds.

Change of anion exchange membranes in an aqueous sodium hydroxide solution at high temperature

Properties of commercial anion exchange membranes were examined after the membranes had been immersed in an aqueous sodium hydroxide solution, 3.0 to 9.0 N, of high temperature, up to 75°C. The anion exchange membranes used had N-methyl-pyridinium groups or benzyl trimethylammonium groups bonded to a styrene-based copolymer as anion exchange groups, with backing polymers. Alkali deterioration of the membranes was classified: decomposition of backing polymers (added inert polymer and backing fabric) and decomposition of anion exchange groups. N-Methyl-pyridinium groups were especially easy to decompose compared with benzyl trimethylammonium groups, and lost ion-exchange ability. Benzyl trimethylammonium groups also lost ion-exchange ability and changed partially in weakly basic anion exchange groups. The anion exchange membranes with various anion exchange groups, benzyl trimethylammonium groups, triethyl-, tri- n-propyl-, tri- n-butyl-, and 1-azonia-4-azabicyclo-[2,2,2]-octane (different hydrophobicity) were prepared from base membranes of chloromethylated polysulfone, and copolymer of chloromethylstyrene and divinylvenzene with polyethylene fabric and powder. Though the membrane based on polysulfone weakened mechanically by immersion the membrane in the alkali solution, polyethylene reinforced-membrane did not change mechanically. However, with increasing chain length of alkyl groups bonded to ammonium groups, loss of the anion exchange capacity was remarkable and 1-benzyl-azonia-4-azabicyclo-[2,2,2]-octane groups were also not stable. The most stable anion exchange groups among these were benzyl trimethylammonium groups.

Synthesis, electrochemistry and ab initio molecular orbital calculations on some norbornane- and bicyclo[2.2.2]octane-fused 5,12-bis(dicyanomethylidene)naphthalene systems

A series of norbornane- and bicyclo[2.2.2]octane-fused tetracyanonaphthoquinodimethane (benzoTCNQ) derivatives, 4,6,8,10 and 12 has been synthesized. Cyclic voltammetry measurements revealed two one-electron reduction waves for the benzo-TCNQ systems 4, 8 and 10 which possess either a cyclobutane or a norbornane moiety fused to the quinonoid ring, but a single (presumably two-electron) reduction wave for 6 and 12 which possess a bicyclo[2.2.2]octane group fused to the gmnonoid ring. The benzo-TCNQ systems were found to be potent electron acceptors. The results of (U)HF/3-21G calculations carried out on representative benzo-TCNQ derivatives suggest that steric interactions between the quinonoid ring and its adjacent fused alicyclic group are largely responsible for the observed decrease in the electron affinities along the series: 8 > 4 > 6. The MO calculations further suggest that LUMO energies of neutral TCNQ derivatives are qualitatively reliable predictors of electron affinities. The calculated (gas phase) internal reorganization energies, λi, for the benzo-TCNQ systems are ca. 54 kJ mol–1 and are comparable to that calculated for the dicyanovinyl (DCV) system, 27. The similarity between the λi values for the benzo-TCNQ systems and 27, together with the experimental finding that benzo-TCNQ systems are reduced at ca. 1.7 V less negative potentials than 27, should make the norbornane- and bicyclo [2.2.2] octane-benzo-TCNQ systems superior to the DCV moiety as acceptor chromophores in giant multichromophoric systems.

Thermotropic copolyesters. III. Synthesis and characterization of liquid crystal copolyesters containing the bicyclo[2.2.2]octane ring system

AbstractA number of thermotropic copolyesters which contain the bicylo[2.2.2]octane ring system have been synthesized. Because of the stiffening effect of the bicyclo[2.2.2]octane group on the chain, the sebacoyl spacer was used to obtain meltable compositions.

Phenyl‐ and Biphenylylbicyclo[2.2.2]octane Derivatives—Two Novel Classes of Nematic Liquid Crystals

The novel liquid crystals (1) and (2) containing a bicyclo[2.2.2]octane group are characterized, inter alia, by the fact that the nematic phase occurs at higher temperatures and over a greater temperature range than in the case of the analogous compounds containing a benzene or cyclohexane ring instead of the bicycle.