Sukjeong Choi

Facile one-pot synthesis of gold nanoparticles using alcohol ionic liquids

We developed a novel synthesis of Au nanoparticles using alcohol ionic liquids. The alcohol ionic liquids simultaneously serve as both reductants and protective agents, thereby significantly simplifying the process of nanoparticle preparation.

Surface tension and viscosity of 1-butyl-3-methylimidazolium iodide and 1-butyl-3-methylimidazolium tetrafluoroborate, and solubility of lithium bromide+1-butyl-3-methylimidazolium bromide in water

The surface tension and viscosity of 1-butyl-3-methylimidazolium iodide ([bmim][I]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) were measured over a temperature range of 298. 15 to 323.15 K. It was found that both the viscosity and surface tension decrease with increasing temperature and that the surface tension and viscosity values of [bmim][I] were higher than those of [bmim][BF4]. Additionally, the solubility of lithium bromide (2)+1-butyl-3-methylimidazolium bromide ([bmim][Br]) (3) in water (1) was measured at three different mass ratios (w2/w3=4 and 7, w3=0) by using a visual polythermal method. The solubility of the suggested systems was better than that of lithium bromide in water.

Structural Transformation due to Co-Host Inclusion in Ionic Clathrate Hydrates

The present findings on the co-host role in restructuring the host water framework might provide important information on tuning the cage dimensions via lattice distortion and promoting the total number of cages via structural transformation. This co-host-induced structural modification can improve the physicochemical properties of ionized clathrate hydrates, particularly given that the host framework is able to function as a pathway to deliver protons or electrons.

Ionic liquids based on N-alkyl-N-methylmorpholinium salts as potential electrolytes

Ionic liquids based on N-alkyl-N-methylmorpholinium salts have been synthesized and the physical and electrochemical characteristics of this family of ionic liquids have been investigated for use as electrolytes.

Discrete Magnetic Patterns of Nonionic and Ionic Clathrate Hydrates

In this communication, the charge transfer phenomenon from ionic host lattice to nonionic guest molecule was observed by magnetization and Raman spectroscopy measurements for nonionic and ionic clathrate hydrates. The present findings on the magnetic property of nonionic guest molecules in ionic hydrate might provide important information on the unrevealed nature of host-guest interaction in ionic hydrate systems. The charge transfer occurring between ionic host and nonionic guest molecules will open up interesting application fields for ionized hydrate complexes and activated secondary guest molecules.

Thermal and electrochemical properties of ionic liquids based on N-methyl-N-alkyl morpholinium cations

A series of ionic liquids based on morpholinium cations were prepared. N-alkyl-N-methylmorpholinium bromide, N-alkyl-N-methylmorpholinium tetrafluoroborate, N-alkyl-N-methylmorpholinium hexafluorophosphate and N-alkyl-N-methylmorpholinium bis(trifluoromethanesulfonyl)imide were synthesized, and then thermal and electrochemical properties of prepared ionic liquids were measured. These morpholinium salts were found to be thermally stable near 673 K and electrochemically stable up to 6 V at room temperature. In conclusion, these new series of morpholinium based ILs might be potential candidates for electrolytes in batteries and other electrolytic devices.

Thermal and electrochemical properties of morpholinium salts with bromide anion

The present work is a study of the thermal properties and electrochemical stabilities of N-ethyl-N-methylmorpholinium bromide ([Mor1,2][Br]), N-butyl-N-methylmorpholinium bromide ([Mor11,4][Br]), N-octyl-N-methylmorpholinium bromide ([Mor11,8][Br]), N-dodecyl-N-methylmorpholinium bromide ([Mor11,12][Br]), and N,N-dihydroxyethylmorpholinium bromide ([DHEMor][Br]). The melting points, decomposition temperatures, and electrochemical stabilities of the salts were measured by DSC (differential scanning calorimetry), TGA (thermogravimetric analysis), and CV (cyclic voltammogram), respectively. All salts were decomposed below approximately 230.00 °C and their melting points were above 100.00 °C except [DHEMor][Br], which melted at 75.17 °C. [DHEMor][Br] appeared to possess the most wide liquid-phase range between melting point and decomposition temperature. The electrochemical windows of salts ranged from 3.3 V for [Mor1,8][Br] to 3.6 V for [Mor1,4][Br] and thus did not show any noticeable variation with cations used for salt synthesis.

Synthesis and Ionic Conductivities of Lithium-Doped Morpholinium Salts

A series of a new type of ionic liquids was prepared. The synthesis and purification procedure of N-alkyl-N-methylmorpholinium bromide, N-alkyl-N-methylmorpholinium tetrafluoroborate, N-alkyl-N-methylmorpholinium hexafluorophosphate, and N-alkyl-N-methylmorpholinium bis(trifluoromethanesulfonyl)imide were presented. Thermal properties of morpholinium salts and ionic conductivities of lithium-doped ionic liquids were measured in the temperature range of 303.15 to 323.15 K. In the case of the pure ionic liquids, the ionic conductivities were 10-4 S·cm-1.