Z/E-Isomerism of 3-[4-(dimethylamino)phenyl]-2-(2,4,6-tribromophenyl)acrylonitrile: crystal structures and secondary intermolecular interactions.

The Z and E isomers of 3-[4-(dimethylamino)phenyl]-2-(2,4,6-tribromophenyl)acrylonitrile, CHBrN, (1), were obtained simultaneously by a Knoevenagel condensation between 4-(dimethylamino)benzaldehyde and 2-(2,4,6-tribromophenyl)acetonitrile, and were investigated by X-ray diffraction and density functional theory (DFT) quantum-chemical calculations. The (Z)-(1) isomer is monoclinic (space group P2/n, Z' = 1), whereas the (E)-(1) isomer is triclinic (space group P-1, Z' = 2). The two crystallographically-independent molecules of (E)-(1) adopt similar geometries.

Characterization of ion profiles in light-emitting electrochemical cells by secondary ion mass spectrometry.

Ion profiles in polymer light-emitting electrochemical cells are known to significantly affect performance and stability, but are not easily measured. Here, secondary ion mass spectrometry is used to investigate ion profiles in both dynamic and chemically fixed junction devices. Results indicate lower reversibility of dynamic junctions and a more significant time delay for ion redistribution than previously expected, but confirm the complete immobilization of ions in chemically fixed junction devices.

Precise color tuning via hybrid light-emitting electrochemical cells.

We report color-tunable light-emitting devices employing CdSe/ZnS quantum dots (QDs) blended into a polymer light-emitting electrochemical cell (LEC) architecture. This novel structure circumvents the charge-tunneling barrier of QDs to achieve bright, uniform, and highly voltage-independent electroluminescence, with nearly all emission generated by the QDs. By blending varying ratios of two QD materials that emit at different wavelengths, we demonstrate precise color control in a single layer device structure.