Piezoluminescence and Liquid Crystallinity of 4,4′-(9,10-Anthracenediyl)bispyridinium Salts

Abstract

Piezoluminescence and liquid crystallinity of anthracene-based bispyridinium salts were investigated in stimulus-responsive luminescent organic crystals and luminescent ionic liquid crystals. The salts possess an anthracene moiety as a fluorophore in their center, and the pyridiniums attached to the anthracene moiety are substituted with trialkoxybenzyl groups. Single crystals of the salts bearing two trimethoxybenzyl groups were obtained as solvates. Ethyl acetate, acetone, and dioxane solvates of the chlorides have almost the same crystal structures with one-dimensional channels. Grinding of the solvated crystals caused the extrusion of the included solvent molecules, which resulted in the red shifts of their fluorescence in the solid state. The dimethyl sulfoxide solvate of the hexafluorophosphate also showed piezoluminescene by grinding. Tris­(octyloxy)­benzyl and tris­(dodecyloxy)­benzyl derivatives exhibited rectangular columnar liquid crystals upon being heated for their bromide and tetrafluoroborate salts and upon being cooled for their hexafluorophosphate salts. Of these pyridinium salts, hexafluorophosphates showed characteristic solvent-dependent fluorescence.

Controlling the structure and photophysics of fluorophore dimers using multiple cucurbit[8]uril clampings

“…It is known that the polarity of CB cavities is lower than that of water, which will also affect photophysical properties of dye molecules. 19,43 Therefore, in the following discussion, a comparison is made between CB[7]-and CB [8]-mediated complexes on account of their similar cavity polarities. A comparison between G 1 -CB[7] 2 and G 2 -CB[8] 2 of Ant910Me shows that the stacking of anthracenyl moieties as a dimer, relative to monomer, exhibits (1) a signicant bathochromic shi in absorption and emission, (2) an elongated excited-state lifetime, and (3) comparably high uorescence efficiency.…”

Current Topics in Ionic Liquid Crystals

“…Kohmoto developed π‐extended viologens by incorporating an anthracene unit in the center of the bipyridinium salt (Scheme 10, 16(R,X) ) [143] . The whole series forms crystalline solvates and X‐ray crystal structures of short homologues (R=CH 3 , X=Cl) reveal incorporation of the solvents in channels.…”

Ionic Liquid Crystals Based on Pyridinium Salts

“…Dicationic pyridinium salts with an anthracene moiety connecting two pyridine rings substitution with tris(alkoxy)benzyl groups 44 were designed and investigated for their liquid crystalline properties and stimulus responsive luminescence [63].…”