Search results for "Conjugated"

Electrochemistry of Bis(pyridine)cobalt (Nitrophenyl)corroles in Nonaqueous Media

2018

International audience; A series of bis(pyridine)cobalt corroles with one or three nitrophenyl groups on the meso positions of the corrole macrocycle were synthesized and characterized as to their electrochemical and spectroscopic properties in dichloromethane, benzonitrile, and pyridine. The potentials for each electrode reaction were measured by cyclic voltammetry and the electron-transfer mechanisms evaluated by analysis of the electrochemical data combined with UV-visible spectra of the neutral, electroreduced, and electroxidized forms of the corroles. The proposed electronic configurations of the initial compounds and the prevailing redox reactions involving the electroactive central c…

Nonlinear optical properties of diaromatic stilbene, butadiene and thiophene derivatives

2021

Series of highly polar stilbene (1a–e), diphenylbutadiene (2a–c) and phenylethenylthiophene (3a–c) derivatives were prepared via Horner–Wadsworth–Emmons method with a view to produce new and efficient materials for second harmonic generation (SHG) in the solid-state. The single-crystal X-ray structures of compounds 1–3 reveal extensive polymorphism and a peculiar photodimerization of the 2-chloro-3,4-dimethoxy-4′-nitrostilbene derivative 1a to afford two polymorphs of tetra-aryl cyclobutane 4. The stilbene congeners 2-chloro-3,4-dimethoxy-4′-nitrostilbene (1a·non-centro), 5-bromo-2-hydroxy-3-nitro-4′-nitrostilbene (1b) and 4-dimethylamino-4′-nitrostilbene (1e), as well as 4′-fluoro-4′′-nitr…

Purification by affinity chromatography of H1 RNA-Binding Proteins from rat brain

2003

Post-transcriptional regulation of mRNA metabolism is involved in processes as different as cell fate specification in development and cell response to a large variety of environmental cues. Regulation of all steps of RNA metabolism depends on RNA-binding proteins (RBPs). By using a T1 RNase protection assay, we previously identified three H1° RNA-binding factors (p40, p70 and p110), highly expressed in the rat brain. Here we report enrichment of these factors from brain extracts, obtained by affinity chromatography of biotinylated H1° RNA-protein complexes on streptavidin-conjugated paramagnetic particles. The purified proteins maintain RNA-binding ability and preference for histone messag…

Metallomacrocycles with metalmetal bonds: synthesis, characterization and electrochemistry of [(P)SnRe(CO)5]BF4 and [{(P)Sn}2Re(CO)4]BF4 derivatives…

1996

Abstract The synthesis and characterization of bimetallic and trimetallic porphyrins of the type [(P)SnRe(CO) 5 ]BF 4 and [{(P)Sn} 2 Re(CO) 4 ]BF 4 are reported where P is the dianion of tetra- p -tolyporphyrin (TpTP) or tetra- m -tolyporphyrin (TmTP). These metal-metal bonded complexes were synthesized by reaction of Re 2 (CO) 10 with the corresponding (P)SnCl 2 derivatives in 1,2-dichlorobenzene followed by a reaction with NaBF 4 or TBABF 4 in toluene to give the BF − 4 salt. Each compound was characterized by a variety of spectroscopic and electrochemical techniques while the structures were assigned on the basis of FAB mass spectral data and by comparison of their physicochemical proper…

Free and conjugated polyamine content in Citrus sinensis Osbeck, cultivar Brasiliano N.L.92, a Navel orange, at different maturation stages

2004

Biogenic amines, synthesized during physiological metabolic processes of all living organisms, are present in food. At low concentrations, polyamines are essential for cell renewal and growth, but they can be detrimental when consumed in high amount through the diet as they could support abnormal cell growth pathologies. The daily human diet contains more putrescine than spermidine or spermine, mostly derived from fruits. In general, orange fruits contain high levels of put, a fact that could limit their utilization in the daily diet besides the benefits contributed by their strong antioxidant properties. There is therefore an increasing interest in finding plant foods with low polyamine co…

The Structural Diversity of Benzofuran Resorcinarene Leads to Enhanced Fluorescence

2014

An unexpected and previously unknown resorcinarene mono-crown with a fused benzofuran moiety in its macrocyclic core was obtained as a byproduct from a bridging reaction of tetramethoxy resorcinarene with tetraethylene glycol ditosylate. The formation of the fused benzofuran moiety in the resorcinarene macrocycle resulted in a unique rigid and puckered boat conformation, as shown by XRD studies in the solid state. Modification of the macrocycle was also observed to affect the photophysical properties in solution by enhancing the fluorescence brightness compared with a conventional resorcinarene macrocycle. The fluorescent properties enabled unique detection of structural features, that is, …

Copper-Catalyzed One-Pot Synthesis of 3-(N -Heteroarenyl)acrylonitriles through Radical Conjugated Addition of β-Nitrostyrene to Methylazaarenes

2020

Cycloalkin-vinylidencycloalkan-umlagerungen

1989

Abstract Flash pyrolysis of the strained cyclic alkynes 1 leads to ring systems 2 with an exocyclic allene group and in a further isomerization step to the conjugated vinyl compounds 3 .

Anthracene Based Conjugated Polymers: Correlation between π−π-Stacking Ability, Photophysical Properties, Charge Carrier Mobility, and Photovoltaic P…

2010

This article reports on the synthesis, characterization and properties of a series of anthracene−containing poly(p-phenylene-ethynylene)-alt-poly(p-phenylene-vinylene)s (PPE−PPV) copolymers with general constitutional unit (Ph−C≡C−Anthr−C≡C−Ph−CH═CH−Ph−CH═CH−)n denoted AnE-PV. Solely linear (AnE-PVaa, -ad, -ae) and solely branched (AnE-PVbb) as well as mixed linear and branched (AnE-PVab, -ac, -ba, -cc) alkoxy side chains were grafted to the backbone in order to tune the π−π-stacking ability of the materials. It has been possible to establish a correlation between π−π-stacking ability, absorptive behavior, charge carrier mobility, solar cell active layer nanoscale morphology and resulting p…

Intercorrelation between Structural Ordering and Emission Properties in Photoconducting Polymers

2009

We investigated the structural properties of anthracene containing poly(p-phenylene−ethynylene)-alt-poly(p-phenylene−vinylene) polymers with general constitutional unit: (−Ph−C≡C−Anthr−C≡C−Ph−CH═CH−Ph−CH═CH−)n by means of wide-angle X-ray scattering and fluorescence spectroscopy. Interchain interactions were systematically modified by decorating the conjugated polymer backbone with linear or branched or combinations of linear and branched alkoxy side chains. Special emphasis is taken on an evaluation method for fiber scattering spectra that allows the deduction of important structural details of polymer materials with limited degree of order. These include positional correlations along the …