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Browsing by Subject "4-Hydroxypyridine"

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    Effect of counterion on the mesomorphic behavior and optical properties of columnar pyridinium ionic liquid crystals derived from 4-hydroxypyridine

    (Elsevier B.V. , 2015)
    Pana, Amalia
    ;
    Badea, Florentina Laura
    ;
    Ilis, Monica
    ;
    Staicu, Teodora
    ;
    Micutz, Marin
    ;
    Pasuk, Iuliana
    ;
    Circu, Viorel
    A series of 3,4,5-tridodecyloxybenzyl pyridinium salts derived from 4-hydroxypyridine has been designed and prepared. The liquid crystalline properties of these compounds were investigated by polarized optical microscopy, differential scanning calorimetry and powder X-ray diffraction while their thermal stability was studied by thermogravimetric analysis. The N-3,4,5-tridodecyloxybenzyl-4-pyridone intermediate shows a monotropic columnar hexagonal mesophase ranging from 56 C down to room temperature while the corresponding bromide dodecyl O-alkylated pyridinium salt shows one enantiotropic columnar mesophase and one additional monotropic columnar phase at lower temperatures. Replacing bromide ion (Br ) with other counterions (NO 3 ; BF 4 and PF 6 ) resulted in mesophase suppression. These luminescent pyridinium salts show weak emission in dichloromethane solutions at room temperature and a pronounced red-shifted emission in solid state. Photoluminescent properties of the pyridinium salts do not depend significantly on the nature of counterion employed.
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