Switchable Green and White Luminescence in Terbium-Based Ionic Liquid Crystals

Magnetic, Photo- and Electroluminescent: Multifunctional Ionic Tb Complexes

In the search for new multifunctional materials, particularly for application in solid-state lighting, a set of terbium salicylato (Sal) complexes of general composition [Cat][Tb(Sal)₄] with the commonly ionic liquid-forming (IL) cations [Cat] = (2-hydroxyethyl)trimethylammonium (choline) (Chol⁺), diallyldimethylammonium (DADMA⁺), 1-ethyl-3-methylimidazolium (C₂C₁Im⁺), 1-butyl-3-methylimidazolium (C₄C₁Im⁺), 1-ethyl-3-vinylimidazolium (C₂Vim⁺), and tetrabutylphosphonium (P₄₄₄₄⁺) were synthesized. All Tb compounds exhibit strong green photoluminescence of high color purity by energy transfer from the ligand in comparison with what the analogous La compounds show, and quantum yields can reach up to 63% upon ligand excitation. When excited with an HF generator, the compounds show strong green electroluminescence with the same features of mission. The findings promise a high potential of application as emitter materials in solid-state lighting. As an additional feature, the Tb compounds show a strong response to applied external fields, rendering them multifunctional materials.

Magnetically Manipulable Ionic Liquid Crystals Incorporating Neutral Radical Moiety

With a view to fabricating a new remote input-output system by applying functional ionic liquid crystalline (ILC) materials, we have developed novel ILC compounds containing a nitroxide radical unit in the organic cations, which show an enantiotropic smectic A (SmA) phase. We have implemented the magnetic manipulation of a droplet of one of the ILC compounds on the basis of the intermolecular magnetic interactions between radical moieties. This ILC monoradical compound shows a 55 % larger increase in paramagnetic susceptibility at the solid-to-LC melting point in the first heating process than the non-ionic LC monoradical compounds. It is most likely owing to the nanosegregation of strongly bonded ionic and non-ionic moieties. The increased molar magnetic susceptibility is preserved not only in the SmA phase but also in the isotropic liquid and solid phases during the first cooling process.

Luminescent Ln-Ionic Liquids beyond Europium

Searching in the Web of Knowledge for “ionic liquids” AND “luminescence” AND “lanthanide”, around 260 entries can be found, of which a considerable number refer solely or primarily to europium (90%, ~234). Europium has been deemed the best lanthanide for luminescent applications, mainly due to its efficiency in sensitization, longest decay times, and the ability to use its luminescence spectra to probe the coordination geometry around the metal. The remaining lanthanides can also be of crucial importance due to their different colors, sensitivity, and capability as probes. In this manuscript, we intend to shed some light on the existing published work on the remaining lanthanides. In some cases, they appear in papers with europium, but frequently in a subordinate position, and in fewer cases then the main protagonist of the study. All of them will be assessed and presented in a concise manner; they will be divided into two main categories: lanthanide compounds dissolved in ionic liquids, and lanthanide-based ionic liquids. Finally, some analysis of future trends is carried out highlighting some future promising fields, such as ionogels.

Developing design tools for introducing and tuning structural order in ionic liquids

Ionic liquids – ionic crystals – ionic liquid crystals? Structural order in imidazolium-based ILs, a series of asymmetrical 1-dodecyl-2-methyl-3-alkylimidazolium bromides, [C₁₂C₁C_nim][Br] with n = 0–12.

Secondary-Sphere Chlorolanthanide(III) Complexes with a 1,3,5-Triazine-Based Ligand Supported by Anion-π, π-π, and Hydrogen-Bonding Interactions

2,4,6-Dipicolylamine-functionalized 1,3,5-triazine (dpat) was isolated. When reacted with LaCl₃, compound [(LaCl₆)(H₃dpat)][H₂O]₂ (1) formed, which crystallized in the monoclinic P2₁/n space group with parameters a = 11.47 Å, b = 19.22 Å, c = 20.98 Å, V = 4652.02 Å, and β = 90.53°. When reacted with NdCl₃, the complex [NdCl₃(H₂O)₄(H₃dpat)][Cl]₃(MeOH)₂ (2) crystallized in the monoclinic P2₁/n space group with unit cell parameters a = 20.05 Å, b = 12.81 Å, c = 20.64 Å, V = 5004.40 Å, and β = 110.20°. In both cases, the dpat ligand forms a bowl-shaped cavity that partially envelops the Ln^III-containing central unit, which is anionic in 1 and neutral in 2. The formation of these outer-sphere complexes is supported by secondary interactions, including π-π stacking, hydrogen bonding, and anion-π between the chlorolanthanide(III) fragment and the electron-deficient 1,3,5-triazine ring. Evidence of protonation of the pyridine rings in dpat was substantiated through the isolation of [H₂dpat][Cl]₂ (3). This compound crystallized in the monoclinic C2/c space group with parameters a = 11.93 Å, b = 20.22 Å, c = 15.28 Å, V = 3664.97 Å, and β = 94.35°. Four pyridine rings are pairwise protonated in 3. dpat showed a moderate ability to extract La^III from an aqueous to an organic phase, indicating its potential, through judicious manipulation of secondary-sphere interactions, as the starting point for efficient extractants for Ln^III ions.

Ionic Liquid Crystals: Versatile Materials

This Review covers the recent developments (2005-2015) in the design, synthesis, characterization, and application of thermotropic ionic liquid crystals. It was designed to give a comprehensive overview of the "state-of-the-art" in the field. The discussion is focused on low molar mass and dendrimeric thermotropic ionic mesogens, as well as selected metal-containing compounds (metallomesogens), but some references to polymeric and/or lyotropic ionic liquid crystals and particularly to ionic liquids will also be provided. Although zwitterionic and mesoionic mesogens are also treated to some extent, emphasis will be directed toward liquid-crystalline materials consisting of organic cations and organic/inorganic anions that are not covalently bound but interact via electrostatic and other noncovalent interactions.

Synthesis, structure and near-infrared photoluminescence of hexanitratoneodymate ionic liquids

Five hexanitratoneodymate-based rare earth complexes () were synthesized using a straightforward method. Purple plate crystals of were isolated and the crystal structure was determined by single-crystal X-ray diffraction with respect to the coordination mode of the nitrate anion to the central Nd(iii) ion. (: monoclinic system P21/c, a = 15.9460(3) Å, b = 10.2457(6) Å, c = 33.323(3) Å, β = 91.8108(17)°, V = 3109.11(11) Å(3), Z = 4). The central Nd(iii) ion is surrounded by six bidentate nitrate ligands, with a major trend towards high symmetry of the [Nd(NO3)6](3-) anion as an icosahedron. Thermal properties were determined from differential scanning calorimetry (DSC) combined with thermogravimetric analysis (TGA) tests. Complexes are found to be room temperature liquids, and their excitation and emission spectra were recorded. These complexes exhibit intense near-infrared (NIR) luminescence emission, which originates from interconfigurational f-f transitions (4)F3/2→(4)IJ multiplet (J = 9/2-13/2). These liquid Nd(iii) complexes are of interest as potential NIR luminescent soft materials with high thermal stability.

Triazolium based ionic liquid crystals: effect of asymmetric substitution

A new series of asymmetrical 1-dodecyl-3-alkyl-triazolium bromides has been synthesized to investigate the effect of asymmetric substitution on their phase behavior.

[Bmim]2SbCl5: a main group metal-containing ionic liquid exhibiting tunable photoluminescence and white-light emission

Presented is an antimony-based photoluminescent material, namely [Bmim]₂SbCl₅, exhibiting bright yellow and white light photoluminescence with quantum yield as high as 86.3%.

Ionic nanoparticle networks: development and perspectives in the landscape of ionic liquid based materials

This article summarizes the research performed on ionic nanoparticle networks compared with other hybrid materials like ionogels or imidazolium modified nanoparticles.