Liquid crystal-directed assembly and phase morphology of a squaraine dye |
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Authors: | Maher A. Qaddoura Paul A. Heiney |
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Affiliation: | 1. Department of Chemistry , University of Central Florida , Orlando , FL , 32816 , USA;2. Department of Physics and Astronomy , University of Pennsylvania , Philadelphia , PA , 19104 , USA |
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Abstract: | The squaraine (SQ) dye, 2,4-bis [4-(N,N-di-n-hexylamino)-2-hydroxyphenyl]squaraine was synthesised, and a series of SQ dye/cholesteryl pelargonate binary mixtures with varying dye concentrations (1%, 3%, 7.5%, 10.8%, 15% and 20% w/w) were prepared. Their phase transitions were investigated using differential scanning calorimetry, polarised light microscopy and X-ray diffraction. The SQ dye itself exhibited no liquid crystalline behaviour. The concentration of the dye in the cholesteric compound proved to have a significant effect on the dye aggregation behaviour and phase transitions in cholesteryl pelargonate, resulting in the appearance of new mesophases and the formation of J- and H-aggregates. The texture morphology, X-ray diffraction data and UV–vis absorbance spectra provide strong evidence of the viability of liquid crystal-directed assembly of the SQ dye. |
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Keywords: | squaraine dyes liquid crystalline mesophase self-assembly J-aggregate H-aggregate |
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