Search results for "Alkoxy group"
showing 10 items of 108 documents
Photochemistry of 3,6-bis(styryl)pyridazines in solution and in neat liquid crystalline phase—optical switching and imaging techniques
2008
Abstract 3,6-Bis(styryl)pyridazines 1a – f with 2–6 alkoxy groups show on irradiation in solution a stereoisomerization which leads to a photostationary state of ( E , E )- and ( E , Z )-isomer. Sensitizing and quenching experiments reveal that the ( E , E )→( E , Z ) route is a pure triplet process, whereas the ( E , Z )→( E , E ) route can have a minor singlet by-reaction. Hexyloxy or dodecyloxy chains on the terminal benzene rings convey the ( E , E )-isomers of compounds 1a , b , d – f thermotropic liquid crystalline properties. In particular S A , S C , and S F/I phases were studied with regard to their photochemical behavior. Depending on the system, photodegradation of the smectic ph…
Oligophenylenevinylenes in Spatially Confined Nanochannels: Monitoring Intermolecular Interactions by UV/Vis and Raman Spectroscopy
2008
Perhydrotriphenylene-based channel-forming inclusion compounds (ICs) and thin films made of polyphenylenevinylene (PPV)-type oligomers with terminal alkoxy groups are investigated and compared in a combined experimental and theoretical approach. Interchromophore interactions and host-guest interactions are elucidated by UV/Vis and Raman spectroscopy. The impact of the local environment of the chromophore on the optical and photophysical properties is discussed in light of quantum-chemical calculations. In stark contrast to thin films where preferential side-by-side orientation leads to quenching of photoluminescence (PL) via non-emissive traps, the ICs are found to be attractive materials f…
Theoretical study of the formation reaction of the methyl vinyl ketone: A conformational approach
2005
The formation reaction of both isomers of the methyl vinyl ketone (MVK) from the corresponding alkoxy radicals was investigated by means of theoretical methods based on quantum chemistry. Perturbative unrestricted Moller–Plesset (UMP2) and density functional methods B3LYP and BH and HLYP were used to obtain the stationary points on the potential energy surface. In addition to this, the interconversion reaction between both isomers of the MVK was studied, characterizing the corresponding transition state. A conformational study was done, and the energy and geometry of the stationary points located were analyzed by means of ab initio calculations. © 2005 Wiley Periodicals, Inc. Int J Quantum …
A combined experimental and theoretical study of the unimolecular elimination kinetics of 2-alkoxypropionic acids in the gas phase
1999
Abstract The reaction mechanism associated with the decomposition of three 2-alkoxypropionic acids (2-methoxy-, 2-ethoxy- and 2-isopropoxypropionic acid) in gas phase to form acetaldehyde, carbon monoxide, and the corresponding alcohol has been analyzed by a combination of experimental and theoretical studies. The kinetics of these systems were determined in a static system over the temperature and pressure range of 301.2–370.7°C and 61–190 Torr, respectively, in seasoned vessel, with the free-radical inhibitor cyclohexene. The experimental data show that these decompositions are homogeneous, unimolecular and follow a first-order rate law. A detailed characterization, at MP2/6-31G** computa…
Palladium-Catalyzed Alkoxy- and Aminocarbonylation of α-Halomethyl Oxime Ethers: Synthesis of 1,3-Alkoxyimino Esters and 1,3-Alkoxyimino Amides
2014
The three component reactions of α-bromomethyl oxime ethers, carbon monoxide, and alcohols or aromatic amines give imino esters and amides, respectively.
Ferromagnetic exchange coupling in a new bis(μ-chloro)-bridged copper(II) Schiff base complex: Synthesis, structure, magnetic properties and catalyti…
2009
Abstract A new (μ-chloro)-bridged complex [Cu(HL)Cl]2 · H2O (1) with the Schiff base ligand H2L, [2-((E)-(2-hydroxyethylimino)methyl)-4-bromophenol], has been synthesized and characterized by elemental analysis, IR, UV–Vis and EPR spectroscopic studies. X-ray diffraction studies show that 1 is a binuclear CuII complex with a pair of chlorine atoms bridging the copper atoms in a central Cu2Cl2 core. Each copper atom in 1 adopts a distorted square-pyramidal geometry with the imine nitrogen atom, alkoxy and phenoxy oxygen atoms from the Schiff base ligand and a bridging chlorine atom constructing the basal plane, while the apical position of the pyramid is occupied by the other bridging chlori…
Alkoxysilylation of π-systems with extended conjugation—reactive chromophores for organic–inorganic hybrid materials
2004
Luminescent stilbenoid chromophores with diethoxysilane end groups are prepared via Heck reactions. Diethoxysilane-substituted styrenes are used as vinylic components, thus allowing the combined connection of the chromophore to the silane moiety with an extension of the π-system. 1,4-Distyrylbenzenes with a terminal bromine are used as coupling partners. The electrical and optical properties the four-ring OPVs are tuned via substitution with donating alkoxy side chains and electron withdrawing cyanide and a naphthyl-1,2,3-oxadiazole moiety. Hydrolysis yields film forming and luminescent cyclosiloxanes.
Tris- and tetrakis-[oligo(phenylenevinylene)]silanes: synthesis and luminescence behaviour
2002
Abstract The connection of three or four monodisperse oligo(phenylenevinylene)s to a central silicon atom is performed via Wittig–Horner reactions. The terminal rings are substituted with alkoxy side chains. Depending on the ratio of the lengths of the rigid conjugated units and the flexible side chains, transparent films can be obtained from several of these trigonal-pyramidal or tetrahedral molecules. An intense fluorescence in the blue-green region is emitted by molecules of either shape. These compounds are interesting as active materials for electro-optical applications due to their intense fluorescence and improved film forming capability.
Formation of silicones mediated by the sponge enzyme silicatein-α
2010
The sponge-restricted enzyme silicatein-α catalyzes in vivo silica formation from monomeric silicon compounds from sea water (i.e. silicic acid) and plays the pivotal role during synthesis of the siliceous sponge spicules. Recombinant silicatein-α, which was cloned from the demosponge Suberites domuncula (phylum Porifera), is shown to catalyze in vitro condensation of alkoxy silanes during a phase transfer reaction at neutral pH and ambient temperature to yield silicones like the straight-chained polydimethylsiloxane (PDMS). The reported condensation reaction is considered to be the first description of an enzymatically enhanced organometallic condensation reaction.
Synthesis, structural and magnetic characterizations of new complexes of di-2,6-(2-pyridylcarbonyl)pyridine (pyCOpyCOpy) ligand
2013
International audience; Using the di-2,6-(2-pyridylcarbonyl)pyridine ligand (L1) as starting framework, five new mononuclear complexes were obtained: [Cu(L1)(MeCN)(ClO4)2] (1) [Co(L1)(MeCN)(Br)2]*MeCN (2), [Fe(L1)2](BF4)2*MeOH*H2O (3), [Cr(L2a)Cl2]*2MeOH (where HL2a is (6-(hydroxyl(methoxy)(pyridin-2-yl)methyl)pyridin-2-yl)(pyridin-2-yl)methanone) (4) and one trinuclear [NiII3] complex, [Ni3(L2b)2(Bz)2(EtOH)2](ClO4)2*2EtOH (where HL2b is (6-(hydroxyl(ethoxy)(pyridin-2-yl)methyl)pyridin-2-yl)(pyridin-2-yl)methanone; Bz = benzoato) (5). Their structural and magnetic characterizations are herein reported. All the metal ions show octahedral coordination geometry, which is slightly unusual for t…