Highly luminescent salts containing well-shielded lanthanide-centered complex anions and bulky imidazolium countercations.

Four salts containing imidazolium cations and europium(III)- or terbium(III)-centered complex anions have been successfully synthesized from an ethanol/H2O solution. The single-crystal X-ray diffraction analyses reveal that these compounds have a common formula of [R][Ln(DETCAP)4] [R = 1-ethyl-3-methylimidazolium (C2mim), Ln = Eu (1) and Tb (2); R = 1-butyl-3-methylimidazolium (C4mim), Ln = Eu (3) and Tb (4); DETCAP = diethyl-2,2,2-trichloroacetylphosphoramidate], in which the lanthanide centers are chelated by four chelating pseudo-ß-diketonate ligands (DETCAP)(-), forming the respective complex anions. Their thermal behaviors and stabilities were also investigated to study the role of the length of the side chain in the cations. Fluorescence measurements at both room temperature and liquid-nitrogen temperature show that these materials show intense characteristic europium(III) or terbium(III) emissions and have long decay times. Their overall quantum yields were determined to be in the range of 30-49%.

Surface-functionalized ionic liquid crystal-supported ionic liquid phase materials: ionic liquid crystals in mesopores.

The influence of confinement on the ionic liquid crystal (ILC) [C(18)C(1)Im][OTf] is studied using differential scanning calorimetry (DSC), polarized optical microscopy (POM), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The ILC studied is supported on Si-based powders and glasses with pore sizes ranging from 11 to 50 nm. The temperature of the solid-to-liquid-crystalline phase transition seems mostly unaffected by the confinement, whereas the temperature of the liquid-crystalline-to-liquid phase transition is depressed for smaller pore sizes. A contact layer with a thickness in the order of 2 nm is identified. The contact layer exhibits a phase transition at a temperature 30 K lower than the solid-to-liquid-crystalline phase transition observed for the neat ILC. For applications within the "supported ionic liquid phase (SILP)" concept, the experiments show that in pores of diameter 50 nm a pore filling of α>0.4 is sufficient to reproduce the phase transitions of the neat ILC.

Controlled assembly of eccentrically encapsulated gold nanoparticles.

Controlled partial attachment of polymer on gold nanoparticles breaks the symmetry of their surface functionalities, allowing tailored assembly of the nanoparticles.

A new class of double alkyl-substituted, liquid crystalline imidazolium ionic liquids--a unique combination of structural features, viscosity effects, and thermal properties.

1,3-Didodecylimidazolium salts have been prepared as first representatives of a new class of ionic liquid crystals (ILCs), showing thermotropic liquid crystalline behaviour in an extended temperature range below 70 degrees C. Remarkably strong non-Newtonian viscosity behaviour was found for the liquid-crystalline state of these ILCs.

Polymer-encapsulated gold-nanoparticle dimers: facile preparation and catalytical application in guided growth of dimeric ZnO-nanowires.

Rational assembly of nanoparticles is of vital importance for exploring fundamental electronic and optical properties and for constructing novel nanoscale devices. Through controlling aggregation kinetics, dimers and trimers of gold nanoparticles were generated and encapsulated with polymer by using a one-pot synthesis that involved simple heating and cooling. Dimers of gold nanoparticles were enriched from the resulting solution by centrifugation. The polymer shells maintain the stability of the nanoparticle organization, preventing aggregation and disintegration during subsequent purification, enrichment, and application. A typical enriched sample showed that the dimer population reached 61% among 989 nanoparticles surveyed. In a proof-of-concept application, the gold nanoparticle dimers were used as catalyst to guide the growth of dimeric zinc oxide nanowires. Nanowire dimers with unprecedented narrow spacing (20 to 60 nm) were achieved using a vapor transport growth method; dimeric nanowire population reached approximately 25%.