Changing absorption intensity ratios for methylene violet Bernthsen in normal alcohols and at different temperatures

[Display omitted] •Methylene Violet Bernthsen displays absorption intensity ratio change as alcohol solvent and temperature change.•Molar absorptivity of MVB in all alcohols was obtained; 1-pentanol, 1-hexanol, and 1-heptanol at different temperatures.•MVB absorption in acetonitrile and water does not display any temperature dependence.•Molecular dynamics simulations of MVB in methanol increase temperature decreases H-bonding at MVB carbonyl.•Computational spectra show loss of absorption intensity at the low energy peak at higher temperature. Absorption spectra of methylene violet Bernthsen (MVB) are reported, obtained in normal alcohols, methanol through 1-octanol, and at different temperatures, 15 °C to 75 °C. Two distinct absorption intensities are apparent. The 565 nm intensity increases relative to the 598 nm intensity as alcohol chain length increases. For each solvent, increasing temperature causes similar intensity ratio effects. Computational spectra of MVB in methanol indicates a decrease in hydrogen-bonding as temperature increases with a corresponding loss of intensity in the low energy peak consistent with the experimental observations. Hydrogen-bonding is indicated as playing a role in the alcoholic solvent effects.