Investigation of absorbance spectra of two triphenylmethanes dyes , such as Malachite Green Carbinol Hydrochloride (MG) and Brilliant Green (BG) in ionic liquids (deep eutectic solvents, DES) prepared from choline chloride and urea (DES-1) or choline chloride and glycerin (DES-2) at different temperatures has been carried out. It was found that solutions of both dyes in DES-1 display �positive� thermochromism, i.e. their blue-green color (maximum of absorbance at 632 and 635 nm for solutions of MG and BG, respectively) significantly decreases on cooling and increases on heating to a boiling water temperature. In contrary, the solution of the same dyes in DES-2 show �negative� thermochromism, i.e. their absorbance at 632-635 nm decreases on heating and increases on cooling. The thermochromic fatigue of both triphenylmethane dyes takes place after 10-15 cycles of heating and cooling. The nature of fatigue is investigated and origin of generated by-products is determined.

Investigation of thermochromic fatigue of triphenylmethane dyes in solutions of ionic liquids

241st National Meeting (2011)

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