Search results for "Planar"
showing 10 items of 412 documents
A Novel Zeolite-Induced Population of a Planar Viologen Conformation. New Viologen Charge Transfer Complexes and Alkene/Viologen/Zeolite Arrays
2004
A rare example of a novel zeolite-induced conformational change and a mechanism for this process are suggested in order to rationalize an unexpected spontaneous intrazeolite reduction observed during preparation of a new viologen (MQ2+)-doped zeolite (NaY). In addition, the formations of six new alkene/viologen/ zeolite charge transfer (CT) arrays using NaMQY and the previously reported NaMVY are also reported. The binding constants between MQ2+ and MV2+ and 2,3-dimethyl-2-butene (TME) were determined using the Benesi-Hildebrand approach, and the stabilities of these CT complexes are compared to their intrazeolite analogue.
Effective conjugation in conjugated polymers with strongly twisted backbones: A case study on fluorinated MEHPPV
2016
Conjugated polymers with strongly twisted backbones, such as MEHPPV with fluorinated vinylene units (F-MEHPPV), demand a redefinition of the all-important ‘effective conjugation length’ ECL, which we extract here by a facile graphical method. In MEHPPV (being essentially planar), the ECL coincides with the ‘maximum conducive chain length’ MCC and extends over about n ≈ 9 repetition units (RU). In F-MEHPPV, the MCC is similarly long with n ≈ 8, but the ECL localizes on just one RU. The strong twist in F-MEHPPV persists in the excited state, broadening the emission spectrum and quenching the fluorescence with reduced radiative and enhanced non-radiative rates.
Fast Response Heating Module for Temperature Programmed GC Analysis in Microreaction Systems
2000
For monitoring the reactant and product concentrations of a gas phase microreactor for ethylene oxide synthesis the development of a miniaturised device for fast GC analysis suitable for operation in conjunction with the microreactor is advantageous. Therefore, a method employing short (0.2 – 0.4 m) packed capillary columns was developed. Highly crosslinked polystyrene microspheres proved to be the most suitable adsorbent enabling a high separation efficiency. For fast temperature programming design concepts for an efficient heating module capable to be used with short capillary columns were developed. In principle, planar as well as cylindrical designs are suitable for integration of a res…
ChemInform Abstract: 4,4,4′,4′,7,7′-Hexamethyl-2,2′-spirobichroman.
2010
The title compound, C23H28O2, was obtained from the reaction of acetone with meta-cresol. The molecular structure consists of two identical subunits which are nearly perpendicular to each other. The oxygen-containing rings are not planar and the molecule is chiral. The crystal structure consists of chains of molecules of the same chirality arranged along the [010] axis.
Structurally diverse second-generation [2.2]paracyclophane ketimines with planar and central chirality: syntheses, structural determination, and eval…
2005
A set of 20 novel [2.2]paracyclophane ketimines with planar and central chirality has been synthesized from enantiomerically pure and racemic 5-acyl-4-hydroxy[2.2]paracyclophane and alpha-branched chiral amines. Their X-ray structures were determined to elucidate the three-dimensional structures and the absolute configuration. The ketimines were used as catalysts in the asymmetric 1,2-addition reactions of diethylzinc with substituted benzaldehydes to furnish chiral alcohols in up to 95 % ee.
A sigma-donor with a planar six-pi-electron B2N2C2 framework: anionic N-heterocyclic carbene or heterocyclic terphenyl anion?
2006
Crystal structure of 1-(2-fluorobenzoyl)-2,7-dimethoxynaphthalene
2014
The asymmetric unit of the compound contains two independent conformers. Each conformer is stacked along the a axis to form columns through van der Waals interactions only.
Crystal structure of (E)-pent-2-enoic acid
2015
The molecule of the title compound, C5H8O2, a low-melting α,β-unsaturated carboxylic acid, is essentially planar [maximum displacement = 0.0239 (13) Å]. In the crystal, molecules are linked into centrosymmetric dimersviapairs of O—H...O hydrogen bonds.
5,10-Dihydroindeno[2,1-a]indene
2019
The title compound, C16H12, crystallizes with four half molecules in the asymmetric unit, each of which is located on a crystallographic centre of inversion. The molecules are essentially planar. The crystal studied was a non-merohedral twin.
Steering of a Sub-GeV electron beam through planar channeling enhanced by rechanneling
2014
We report the observation of efficient steering of a 855 MeV electron beam at MAMI (MAinzer MIkrotron) facilities by means of planar channeling and volume reflection in a bent silicon crystal. A $30.5\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$ thick plate of (211) oriented Si was bent to cause quasimosaic deformation of the (111) crystallographic planes, which were used for coherent interaction with the electron beam. The experimental results are analogous to those recorded some years ago at energy higher than 100 GeV, which is the only comparable study to date. Monte Carlo simulations demonstrated that rechanneling plays a considerable role in a particle's dynamics and hinders the spoiling…