Dicationic ionic liquid crystals: Synthesis, characterization, optical properties, and ionic conductivity of bis(4-oligoethyleneoxyphenyl) viologen bistosylate salts
Document Type
Article
Publication Date
3-15-2024
Abstract
Three bis(4-oligoethyleneoxyphenyl) viologen bistosylate salts of different lengths were prepared via the Zincke reaction followed by a metathesis reaction with silver tosylate, and their chemical structures confirmed by 1H, 13C nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) techniques, and elemental analysis. Thermogravimetric analysis (TGA) showed these salts had excellent thermal stabilities, losing just 5 of their initial mass between 283 and 288 °C. Liquid crystalline phases and transition temperatures were determined by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and variable temperature X-ray diffraction (VTXRD) techniques. The salts exhibited weak fluorescent emission in dichloromethane and no emission in acetonitrile but exhibited light emission in the solid state. Their absolute quantum yields ranged between 3 and 12 . Impedance spectroscopy showed that the ionic conductivity of the salts increases with the number of oxyethylene units in the extended viologen moiety. The salt-containing four oxyethylene units at each end reach a conductivity value of 10-2 S·cm−1, attributed to its larger molecular flexibility and improved ionic liquid mobility. © 2024 Elsevier B.V.
Keywords
Dichloromethane, Differential scanning calorimetry, Fourier transform infrared spectroscopy, Ionic conductivity, Ionic liquids, Liquid crystals, Nuclear magnetic resonance, Optical data storage, Optical microscopy, Optical properties, Salts, Silicones, Sulfur compounds, Thermogravimetric analysis, Dicationic ionic liquids, Ionic liquid crystals, Liquid crystal synthesis, Metathesis reactions, Oxyethylene, Polarized optical microscopy, Variable temperature, Variable temperature X-ray diffraction, Viologens, X- ray diffractions, X ray diffraction
Divisions
PHYSICS
Funders
University of Nevada Las Vegas (UNLV),Faculty Opportunity Award (FOA) that is adminis-tered by the Office of Sponsored Programs (OSP) at UNLV
Publication Title
Journal of Molecular Liquids
Volume
398
Publisher
Elsevier B.V.