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Emitting Cell (emitting + cell)

Distribution by Scientific Domains

Chemistry	50%

Selected Abstracts

Ionic Iridium(III) Complexes with Bulky Side Groups for Use in Light Emitting Cells: Reduction of Concentration Quenching

ADVANCED FUNCTIONAL MATERIALS, Issue 13 2009
Carsten Rothe
Abstract Here, the photophysics and performance of single-layer light emitting cells (LECs) based on a series of ionic cyclometalated Ir(III) complexes of formulae and where ppy, bpy, and phen are 2-phenylpyridine, substituted bipyridine and substituted phenanthroline ligands, respectively, are reported. Substitution at the N,N ligand has little effect on the emitting metal-ligand to ligand charge-transfer (MLLCT) states and functionalization at this site of the complex leads to only modest changes in emission color. For the more bulky complexes the increase in intermolecular separation leads to reduced exciton migration, which in turn, by suppressing concentration quenching, significantly increases the lifetime of the excited state. On the other hand, the larger intermolecular separation induced by bulky ligands reduces the charge carrier mobility of the materials, which means that higher bias fields are needed to drive the diodes. A brightness of ca. 1000,cd,m,2 at 3,V is obtained for complex 5, which demonstrates a beneficial effect of bulky substituents. [source]

Regulation of Exocytosis in Chromaffin Cells by Trans -Insertion of Lysophosphatidylcholine and Arachidonic Acid into the Outer Leaflet of the Cell Membrane

CHEMBIOCHEM, Issue 12 2006
Christian Amatore Prof.
Abstract Vesicular exocytosis is an important complex process in the communication between cells in organisms. It controls the release of chemical and biochemical messengers stored in an emitting cell. In this report, exocytosis is studied amperometrically (at carbon fiber ultramicroelectrodes) at adrenal chromaffin cells, which release catecholamines after appropriate stimulation, while testing the effects due to trans -insertion of two exogenous compounds (lysophosphatidylcholine (LPC) and arachidonic acid (AA)) on the kinetics of exocytotic events. Amperometric analyses showed that, under the present conditions (short incubation times and micromolar LPC or AA solutions), LPC favors catecholamine release (rate, event frequency, charge released) while AA disfavors the exocytotic processes. The observed kinetic features are rationalized quantitatively by considering a stalk model, for the fusion pore formation, and the physical constraints applied to the cell membrane by the presence of small fractions of LPC and AA diluted in its external leaflet (trans -insertion). We also observed that the detected amount of neurotransmitters in the presence of LPC was larger than under control conditions, while the opposite trend is observed with AA. [source]

Dynamics of Full Fusion During Vesicular Exocytotic Events: Release of Adrenaline by Chromaffin Cells

CHEMPHYSCHEM, Issue 2 2003
Christian Amatore Prof.
Abstract Vesicular exocytosis is important in the communication between cells in complex organisms. It controls the release of specific chemical or biochemical messengers stored in the emitting cell, which elicit a response upon detection by the target cells. Secretion of a messenger molecule (a neurotransmitter) was measured electrochemically, which allowed the quantification of cellular events and the validation of current physicochemical models. This model led us to formulate predictions about the occurrence and kinetics of vesicular exocytotic events based on the physicochemical meaning of its key parameters. These predictions were tested successfully through a series of experiments on chromaffin cells, involving changes of osmotic conditions, presence of trivalent ions and cholesterol-induced structuring of the cell plasmic membrane. [source]